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EVALUATION OF THRESHOLD STRESS OF SUBGRADES FOR HIGHWAY FORMATION BASED ON THE UNCONFINED CYCLIC TRIAXIAL TEST Elsa Eka Putri ( ) PhD Student, School of Engineering and Information Technology, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia 88999 (Lecturer, University of Andalas, Indonesia) e-mail: elsaeka@ft.unand.ac.id, elsaeka@gmail.com N.S.V Kameswara Rao Professor, School of Engineering and Information Technology, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia 88999 e-mail: nsv@ums.edu.my. M. A. Mannan Professor Madya, School of Engineering and Information Technology, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia 88999 e-mail: mannan@ums.edu.my. ABSTRACT: Subgrade for highway formation is the lowest pavement layer that affords all the stress induced from all pavement layers above including the traffic loading. The applied stress from the traffic loading, is supposed to be in cyclic shape, and should be less than the shear strength of the pavement material that it can sustain. Threshold stress is the stress level above which the stress can lead to excessive permanent deformation due to cyclic loading. Thus to evaluate the threshold stress soil subgrade is important in order to produce a good design of highway formation. In this investigation, the threshold stress was studied from the point of view of cyclic deviator stress from unconfined cyclic triaxial test. Cyclic deviator stress is the stress level during cyclic loading, and the incremental of cyclic deviator stress was chosen from the small to the highest stress which can lead to permanent deformation or the failure of the sample. The compacted clayey sand soils are tested using the GDS triaxial testing instrument. The relationship between the incremental values of permanent strain in the axial direction is developed. It can be concluded that for ratio of threshold stress more than 70% the permanent axial strain becomes very high leading to failure of the samples. Keywords: Threshold stress; cyclic stress ratio; unconfined cyclic triaxial test 1. INTRODUCTION

Many structures are subjected to cyclic loading. This includes railway track as well as the highway and runway formation (subgrade). With the increasing traffic axle loads, speeds and traffic density, the conventional design method used for designing the highway and runway pavements need to be improved for better performance and low maintenance cost of highways. Subgrade as a highway or runway foundation should be stressed well below the limits of failure stress induced by the traffic loading and it should not exceed the threshold stress of subgrade soils. Threshold stress is the highest level of stress that subgrade can still deal with so that subgrade formation will not deform excessively due to repeated loading of the moving vehicle. This test was developed to investigate the

behaviour of the soil subgrade that experiences the cyclic loading due to moving wheel loads of vehicles.

Thus evaluation of the threshold stress and using it for better design for constructing the highway and runway formation is necessary which can be obtained using the unconfined cyclic triaxial test.

2. LITERATURE REVIEW

Subgrade of the pavement is laid either in cutting or on fill area, depending on the topography itself. When the subgrade is laid in fill, the compaction should be properly done to fulfill the requirements of the formation. Hence, for standardization of testing, tests are done on the compacted samples

The specimen deformation will be independent of the frequency if the maximum number of cycles is 100,000 and it depends only on total number of cycles (Sangrey 1968, Shahu 1993).

The threshold stress is based on the development of plastic strain with number of cycles at different cyclic stress ratios. Shahu (1999) carried out threshold stress studies based on the concept of Rubin et. al (1970) that threshold stress is defined as a maximum stress that can be applied to the sample that does not cause cumulative strain greater than 10 percent in 1000 cycles. Threshold stress (critical level of repeated stress) value is not a basic material parameter but is dependent on mean effective stress, loading wave shape, frequency and previous loading history.

Fall et. al, (1997) carried out monotonic and cyclic triaxial loading tests on reconstituted samples of western Senegalese laterites. In order to model the response of the soils under the traffic load the permanent strain results and variation of the resilient modulus during loading are considered.

Shahu (1999) conducted the tests on alluvial silty clay known as Gangetic silt using unconfined cyclic triaxial test. He has studied the unconfined cyclic triaxial test as a proposed test methodology to develop the threshold stress for the soil for the design of railway formation and found that there is significant change in stiffness of the soil due to cyclic loading.

Shahu et al (2000) had developed a threshold stress approach for subgrade soils with the basis of the design such that it keeps the induced maximum deviator stress on the subgrade well below its threshold stress. Changes in plastic strain generation on cyclic loading and stiffness of the soil are relevant to highway and runway pavement formations. He defined the parameter Rf which is called cyclic stress ratio for purposes of analyzing the results.

Rf (cyclic stress ratio) is defined as the ratio at which a sudden increase in incremental plastic strain occurs (Shahu et. al 1999). Thus, based on studies related to development of plastic strain the relationship between cumulative plastic strain and cyclic stress ratio has been evaluated.

The cyclic stress ratio was also studied by Attya et. al (2007) who used the definition of cyclic stress ratio developed by Brown et. al (1975) and Zhou and Gong (2001). They define the cyclic stress ratio as the ratio between cyclic deviator stress qcyclic to the static deviator stress at failure qfailure.

3. METHODOLOGY

For evaluation of the threshold stress, tests are conducted on locally available clayey sands with the Liquid Limit of 53%, Plastic Limit of 23.7% and Specific Gravity of 2.55. In order to study the threshold stress of the soil the unconfined cyclic test (Shahu, 1993). The soil sample is tested in unconfined condition. The sample is then subjected to 100 load cycles at 1 cycle per minute in undrained condition. The soil was then tested to failure in undrained loading.

In this investigation the formation was assumed to be laid on filling embankment. Thus the compacted sample was prepared to indicate that the formation is on the compacted subgrade. The soil was compacted using modified Proctor compaction test as per BS 1377-4:1990.

Sample is subjected to cyclic load with defined cyclic stress ratio, Rf., as a percentage defined as

Rf = (qr / qu ) x 100 (1)

where qr is the cyclic deviator stress and qu is the unconfined compressive strength.

Calculating qu from an unconfined compression test on a similar sample and also estimate the qr, cyclic stress ratio can subsequently be determined. The cyclic deviator stress level has been varied, while the frequency is kept constant for all tests. The incremental cyclic deviator stress was chosen from the small to the highest stress which can lead to permanent deformation or the failure of the sample.

4. RESULTS

4.1. Soil Classification

Soil was collected along the Sulaman road Kota Kinabalu, Sabah. Within the scope of the laboratory studies, index properties, compaction characteristics, classification tests, and California Bearing Ratio (CBR) tests of the subgrade soil were performed to determine the geotechnical properties of the material. The results were shown in Table 1. The particle size distribution analysis of the soil involves determining the percentage by weight of particles within the different size ranges.

Table 1. Index Properties, Compaction Characteristics, Classification, and CBR of Soil.

Soil Properties

Liquid Limit 56 %

Plasticity Index 33.8 %

Specific Gravity 2.56

Classification USCS SC/SP

AASHTO A-2-7

Standard Proctor

Optimum Moisture Content 18%

Max. Dry Density 1647 kg/m3

Modified Proctor

Optimum Moisture Content 13%

Max. Dry Density 1918 kg/m3

CBR value 6.5%

 

4.2. Unconfined Compressive Triaxial Test

From the modified Proctor compaction test result, the sample was prepared to be tested for the unconfined compressive strength. In this test, the sample was mounted on the triaxial apparatus. The conventional monotonic unconfined compression tests were carried out following the procedure given by Bishop & Henkel (1962). The results are shown in Figure 1.

   

Fig.1. Deviator stress of the soil from the static monotonic shear.

As shown in Figure 1, the average unconfined compressive strength of the clayey sand from monotonic unconfined triaxial compression test is 967.475 kPa.

4.3. Maximum Deviator Stress with varying cyclic stress ratio

The result of unconfined cyclic triaxial test after 100 cycles of loading is presented in Figure 2.

Figure 2 shows data of the cyclic stress ratio imposed to the sample. It can be seen that the higher the cyclic stress ratio, Rf, will be resulted in maximum deviator stress and

the higher of the deformation as indicated by the higher of the axial strain.

Fig. 2. Maximum of deviator stress occur after 100 cycles

In Figure 3 present the data of the moisture content, bulk density and maximum dry density of the entire sample tested in laboratory.

Fig.3. Moisture content, bulk density and dry density for all samples

It can be seen from Figure 3 and related to Figure 2 that there is no relationship apparent between the moisture content changes and the deviator stress result.

4.4. The deformation due to cyclic loading

The cyclic loading leads to an accumulation of deformation that can cause the permanent deformation. The deformation of the sample after 100 cycles of loading is presented in Figure 4.

Figure 4; Deformation of the sample due to cyclic shear loading

As seen on Figure 4, the deformation of the sample will develop quickly, as the cyclic stress ratio increased. It can be noted from Figure 4, at low cyclic stress ratios which are below 50% the deformation of the sample, axial strain

is still below 5% and the soil sample can still sustain the cyclic loading utilization up to 100 cycles. Moreover, as the cyclic stress ratio is increased above 50% the deformations of the sample are increased sharply. It leads to the failure of the sample. In this study for the cyclic stress ratio above 70%, the clayey sand soils will fail before 100 cycles of loading.

4.5. Determination of threshold stress

Figure 5 has been drawn based on the results of unconfined cyclic triaxial test. There are three parameters that have been studied. Firstly, permanent strain at failure, based on the monotonic loading result after application of the cyclic loading to the sample is determined. Secondly, permanent strain after 100 cycles, axial strain is determined. Thirdly, permanent strain before cyclic loading, the axial strain result is recorded.

Figure 5; Plastic Strain vs. Rf for unconfined cyclic tests

For all the clayey sand soils samples, the permanent strain at failures is above 7.5% in average. As the ratio of cyclic stress, Rf, is increased, consequently the permanent strain increases sharply. Moreover, the permanent strain before cyclic loading was high for the Rf above 70%.

For higher Rf, the samples will have a high deformation. As can be seen in Figure 5 (indicated with arrows, for Rf more than 70%), the sample is failing with excessive strains in less number of cycles and the permanent axial strain at 100 load cycles becomes very high, leading to

failure of the sample. The corresponding value of plastic strain, εp after 100 cycles, for the case of unconfined tests on soil samples compacted at optimum moisture content is of the order of 7.5%.

5. CONCLUSIONS

As the soil samples deform quickly when the cyclic stress ratio is 70% or above, it means that the threshold stress

ratio of this soil is 70%. This value is more suitable to be used as a parameter of highway and runway formation design because it gives a much better insight into the soil behaviour under repeated loading, thus simulating the field soil condition subjected to passing wheel loads. However, since the threshold stress values are based on laboratory tests conducted under idealized condition, for example at optimum moisture content or at room temperature, etc, it is suggested that the design formation depth based on this approach be increased by 25% (Shahu, 1993). This recommendation is primarily meant to take into account the actual highway pavement layers and drainage prevailing in the field.

ACKNOWLEDGEMENT This project is sponsored by the FRGS (Fundamental Research Grant Scheme) Universiti Malaysia Sabah no. FRG0074-TK-1-2006 and FRG 174-TK-2008

REFERENCE

Attya, A., Indraratna, B., and Rujikiatkamjorn, C. (2007). Cyclic behaviour of PVD-soft soil subgrade for improvement of railway tracks. Proceedings of the 10th Australia New Zealand Conference on Geomechanics, Brisbane, Australia, 21-24 October 2007, 2, 36-41

BS 1377-4:1990.Method of Test for Soils for Civil Engineering Purposes

M. Fall, J. -P. Tisot, and I. K. Cisse, (1997). Undrained Behaviour of Compacted Gravel Lateritic Soils from Western Senegal under Monotonic and Cyclic Triaxial Loading , Engineering Geology 47(1-2): 71-87.

Kim D, Kim J. R. (2007). Resilient Behavior of Compacted Subgrade Soils under the Repeated Triaxial Test. Construction and Building Materials. 21 pp. 1470-1479

Koike, M., T. Kaji, Usaborisut, P.,Takigawa, T.,, Yoda, A., Takahashi S. (2002). Several contributions to soil compactibility induced by cyclic loading test. Journal of Terramechanics 39(3): 127-141.

Shahu, J.T.,(1993). Some Analytical and Experimental Investigation to Predict the Behaviour of Soil under the Railway Tract. PhD thesis, IIT Kanpur.

Shahu, J.T., Yudhbir, and Kameswara Rao, N.S.V.(1999). A simple test methodology for soil under

transportation routes. Geotechnique 49, No. 5, pp 639-649

Shahu, J. T., Yudhbir, Kameswara Rao, N.S.V. (2000). A rational method for design of railroad track foundation, soils and foundations. Japanese Geotechnical Society. Soil and Foundation vol.40.

Zhou, J., and Gong, X. (2001). Strain degradation of saturated clay under cyclic loading. Canadian Geotech. J. 38(1): 208–212 (2001)

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OPTIMUM BINDER FOR POROUS MIXTURES MADE BY VARIOUS

AGGREGATE GRADATIONS AND ITS PROPERTIES TOWARDS

PRODUCING GROUTED MACADAM COMPOSITE PAVEMENT

Nadiah Md. HUSAIN Hilmi MAHMUD Postgraduate Student Professor

Dept. Of Civil Engineering Dept. of Civil Engineering

University Malaya University Malaya 50603 Kuala Lumpur 50603 Kuala Lumpur

Malaysia Malaysia

Tel: 603 – 79675203 / 5339 Tel: 603 – 79675203/5339 E-mail: nadiah.husain09@gmail.com E-mail: hilmi@um.edu.my

Mohamed Rehan KARIM Professor

Dept. Of Civil Engineering

University Malaya

50603 Kuala Lumpur Malaysia

Tel: 603 – 79675201 / 5339

E-mail: rehan@um.edu.my

Grouted Macadam (GM) is generally a composite pavement which is manufactured by preparing a highly workable fluid mortar which is specially designed with a very high early and 28 day strength (1 day-45 MPa, 28 day-105MPa) by filling the water consistency fluid mortar into a very open porous asphalt skeleton (25-35% VIM). The combination of both components will produced a semi-flexible pavement or GM which has the best features of both concrete and flexible pavement where it will replace the conventional wearing course. The aim of this investigation is mainly to find the optimum binder for three (3) different aggregate gradations (max, mid, min) by Road Engineering Association of Malaysia (REAM) and its properties towards producing a grouted macadam composite pavement. These include voids in mix (VIM), Bulk Density, and Resilient Modulus (IDT). The optimum binder was achieved by a binder drainage test (BDT) developed by Road Engineering Association of

Malaysia (REAM), similar to the Transport Research Laboratory, UK and commonly used to set an upper limit on the optimum binder content. The results indicated that maximum aggregate gradation requires the least percentage of binder followed by median and finally minimum aggregate gradation. It can be concluded that the more porous the sample (high in VIM), the lesser the percentage of binder were to be used and vice versa. Finally, it also shows that the three (3) different aggregate gradations significantly affected its main properties mentioned.

Keywords: Binder drainage test, Porous Asphalt, Aggregate Gradation

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1. INTRODUCTION

Pavements or road surface is the durable surface material laid down on an area intended to sustain

traffic – vehicular or foot traffic. In other word, it is

the structure which separates the tires of vehicles

from the underlying foundation material. The choice

of road surfacing has traditionally been between

asphalt (flexible) pavement and the concrete (rigid)

pavement. Flexible pavement consists of asphalt as a

binder (sticky, black and highly viscous liquid or

semi-solid that is present in most crude petroleum)

mixed with various sizes of mineral aggregates. The

total pavement structure deflects under loading. A

typical flexible pavement composed of several layers which every layer receives loads from the above

layer and spreads them out, and then passes these

loads to the next layer below. Thus, the deeper the

layer, the less load it must carry. Concrete pavement

on the other hand typically comprises of binder

(cement), water and aggregates. This type of structure

deflects very little under loading due to its high

modulus of elasticity of its surface course. Because of

its relative rigidity, the pavement structure distributes

loads over a wide area with only one or at most two

structural layers compared to flexible pavement. Due to the depth of concrete layer, it will eventually

increase the cost of production.

Road surfacing pavement has always been one of the

major issues in the most developing countries.

Finding the best design of surfacing layer had been a

positive competition among manufacturers and

designers. Road surfacing pavement demands

adequate strength to ensure satisfactory durability. Both pavement types discussed have their own

advantages and also shortcomings. As for example,

rutting as a result of increased stresses in heavy-duty

pavements is the main cause of deterioration of

flexible asphalt surfacing (Lister & Addis 1977).

Rigid pavement on the other hand can be susceptible

to relatively slow setting times during the

construction phase and poor riding quality (and

noise) caused by the joints required to accommodate

differential expansion/contraction during service

(Hassan et al., 2002).

However, another alternative solution to overcome

the limitation and drawback caused by the commonly

road surfacing would be the joint-less Semi-Rigid

pavement surfacing. The resultant combination

consist both the flexibility from the bituminous

component and the rigidity from the cement

constituent. Semi-Rigid pavement surfacing

composed of porous asphalt skeleton filled with the best selection of fluid grout tested. Thus, producing a

very high workability fluid grout and at the same

time attain a relatively high compressive strength is

required to bond together the two composition with

minimal porosity (<8%). Porous asphalt skeleton is

manufactured by using bitumen as binder, course

aggregates and fine aggregates. Very open porous asphalt is required in order to allow a self compacting

cementitious grout to impregnate into the porous

asphalt skeleton under the influence of gravitational

force. Thus it is important that the porous asphalt

skeleton to achieve a very high air voids content of

28-32% with a depth of 100mm each sample

prepared ant at the same time maintain a very thick

layer of bitumen coating the aggregates.

Pervious or porous surfacing materials were initially

developed in the United Kingdom in the 1950‟s.

However, it was not until recently that Porous

Asphalt (formerly known as Pervious Macadam or

Friction Course) has been used to any significant

degree on British highways (Woodside A. R. et. al.).

This has not been the case on mainland Europe

where, over the past 5 to 10 years, the use of Porous

Asphalt has expanded dramatically in countries such

as France, Belgium, Holland, Austria and

Switzerland (Fabb T.R.J. 1993). In Malaysia, the first application of porous asphalt pavement took place in

1991 and followed in the year 1995 on the Federal

Highway. The porous asphalt section along the

Federal Highway carries some of the heaviest traffic

and has recently been resurfaced with porous asphalt.

(Hamzah M.O. et. al.).

Many agencies around the world use different

terminologies for porous asphalt pavement, and

specifications that are slightly different. The various

terminologies used include open-graded asphalt

(OGA), open graded friction course (OGFC), and porous friction course (PFC), (Suresha S.N. et. al,

2009). But practically, all of the mentioned

terminologies were actually gave the same meaning

and purpose which is a highly porosity or air void

content pavement compared to the conventional

asphalt pavement. Pavements with open-graded

asphalt mixes were found to improve wet weather

skid resistance, minimize hydroplaning, reduce

splash and spray, and also reduce tyre-noise (Huber

G.)

The minimum air voids content specified by some of

the agencies or standards were actually dependent on

the traffic volume. Some countries specified the

minimum air voids depending on the traffic volume

and some does not. ASTM D 7064 suggested that a

typical open graded asphaltic mixes should have a

minimum percentage air voids of 18% in order to

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withstand traffic loading. This percentage air void is

slightly lower than those manufactured for the

purpose of semi-rigid pavement. This is due to the

fact that porous asphalt asphaltic pavement stands on

its own while porous asphalt skeleton with high

percentage of air voids will later to be filled with high strength fluid grout which eventually will have

exhibited much lower porosity (<8%).

2. BACKGROUND

Grouted Macadam Wearing Course is manufactured by the production of both a very open Porous Asphalt

together with a very high workability fluid grout.

This paper is mainly focusing on the production of

Porous Asphalt skeleton where three different

aggregate gradations were chosen in order to see the

significance different between the two boundary lines

(max and min).

One of the important criteria that need to be aware of in producing Porous Asphalt is the amount of binder

usage to coat the aggregate. It is crucial to have the

optimum binder coating the aggregates film thickness

as to prevent rapid oxidation of binder. Eventually

weaken the bonding between the binder and

aggregates. Thus, an optimum binder test has to be

carried out in order to accomplish the right amount of

binder that requires for a certain aggregate gradation.

Optimum binder is also required to maintain the

aggregates to be intact in its original position without

having neither thin coats nor excessive coating. Thin coats binder film thickness will not give enough

stiffness to maintain the aggregate from friction and

durability. Bitumen will get aged and oxidation may

easily take place. Studies shows that inadequate

binder film thickness will eventually caused raveling

and cracks. Thicker coats binder film thickness will

risk of excessive binder run-off during mixing,

transportation and also laying. Henceforth will cause

clogging of voids after laying process and reduce the

important properties of porous mix.

Porous Asphalt skeleton were produced by using

Marshall Method with 50 compaction blows on upper

and lower face of the sample. The 50 compaction

blows is an acceptable compaction value for medium

traffic flow (Wright and Dixon, 2004) and an

acceptable value to produce a desired voids in mix

(VIM). The desired VIM is essential towards

producing Grouted Macadam Wearing Course as it

will enhance the ease of filling the voids by fluid grout via gravitational force without the aid of

vibration as it may damage the porous asphalt due to

high percentage of air voids.

3. OBJECTIVES

The main objective of this laboratory investigation is to determine the optimum binder for three different

aggregate gradations by Road Engineering

Association of Malaysia (REAM) and to see its

significance difference towards producing Grouted

Macadam Wearing Course.

4. SAMPLING AND TEST PLANS

4.1 Materials

The materials used in the investigation are the

conventional bitumen 80/100, crushed aggregates

with porous mix gradation and also Portland Cement

acts as filler. Crushed aggregates were supplied by

Hanson, Kajang and the bitumen 80/100 was supplied by Kajang Rock. Table 1 and 2 below shows

the physical test that has been run onto the course

aggregates and bitumen binder before any laboratory

test on Porous Asphalt mixtures were carried out.

Table 1: Physical Test on Course Aggregates

Flakiness Index (FI) – BS812 Part 105.1

20.8

Elongation Index – BS812 Part 105.2

21.2

Aggregate Impact Value (AIV) – BS812 Part 112

Aggregate Crushing Value (ACV) BS812 – Part 110

Table 2: Physical Test on Bitumen 80/100

Softening Point, oC – ASTM D36 45 - 50

Penetration at 25 oC, 100g, 5s, 0.1mm – ASTM D5

80 - 100

Ductility at 25 oC, 5cm per min – ASTM D113

80 - 100

Flash Point (Cleveland open cup) oC – ASTM D92

200

Figure 1: Aggregate Gradations for Porous Mix

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Figure 1 shows the 3 aggregate gradations for Porous

mixtures that have been analyzed and evaluated in

this study. In this preliminary investigation of

Grouted Macadam Wearing Coarse, the coarsest

aggregate gradation (G1) mostly consists of 96%

coarse aggregates and 4% fine aggregates. The finest aggregate gradation (G3) on the other hand comprises

of 86% coarse aggregates and 14% of fine

aggregates. Coarse aggregates define those aggregate

sizes from 4.75mm and above while fine aggregate

indicates those aggregates size from 4.75mm and

below.

4.2 Binder Drainage Test (BDT)

The optimum binder was achieved by a binder

drainage test (BDT) developed by Road Engineering

Association of Malaysia (REAM), similar to the

Transport Research Laboratory, UK and commonly

used to set an upper limit on the optimum binder

content. Each aggregate gradation will undergo a 3

times repetition test for a series of binder contents

and the amount of material drained measured each time. The retained binder (R %), is calculated from

Eq. (1) and Figure 2 shows the typical plotting. The

mixed binder content M is assumed to coincide with

0.3% drainage. The target binder content is

equivalent to (M-0.3) %. According to Hamzah M.O.

et. al., the term „target binder content‟ or the

„optimum binder‟ refers to the maximum binder

content that can be safely accommodated without the

risk of excessive binder run-off during mixing,

transport and laying process.

R = 100 x B [1-D/(B + F)]/(1100 + B) (1)

Where,

D = mass of binder n filler drained (g)

B = initial mass of binder and filler drained (g)

F = initial mass of filler in the mix (g)

Figure 2: Binder Drainage Test Typical Plot

4.3 Marshall Mix Sampling – ASTM D1559

Marshall mix samples were done based on ASTM D 1559 standard. The temperature of each sub-

procedure has to be taken seriously into account. This

is due to the fact that overheated bitumen will affect

the bitumen binder by oxidation or by aging. Table 3

shows the mixing and compaction temperature that

has been used during the preparation of Marshall

mix. A compaction effort of 50 blows was applied on

both upper and lower sample.

Table 3: Temperature for Marshall mix preparation

Mixing Temperature, oC 160 – 180

Compaction Temperature, oC 130 – 140

4.4 Air Void Test - ASTM D 3203-94

Preparation and calculation of air void test were done

according to ASTM D 3203-94.Voids in mix (VIM)

is calculated with the following Eq. (2)

VIM (%) = 100 – (Vol. of bit. + Vol. of agg.) (2)

4.5 Bulk Density (BD) - ASTM D 3203-94

From the air void tests, bulk density can be calculated

with the following Eq. (3).

Bulk density (g/ml) = Wa/Vol (3)

Where,

Wa = mass of Marshall sample in air (g)

Vol = volume of Marshall sample (ml)

4.6 Indirect Tensile Test – Resilience Modulus

Resilience modulus is computed by the indirect

tensile test (IDT) were done according to ASTM D –

4123 (82) standard. It was carried out using the

Universal Material Testing Apparatus (MATTA).

The resilient modulus test involves the application

and the measurement of a stress and measurement of

resultant displacement and hence strain. The resilient

modulus is determined by dividing stress by strain.

The testing parameters are as follows:

i. Temperature : 25oC

ii. Force : 20 x Specimen Depth

iii. Pulse Period : 1 second

Indirect tensile test (IDT) is non-destructive test (NDT) method, which referring to a method that

evaluates properties of material or a system without

causing damage to the sample. This test was done to

5

assess the sample deformation properties under

dynamic load application.

5 RESULTS AND DISCUSSION

5.1 Binder Drainage Test (BDT)

The results of binder drainage test for conventional

80/100 bitumen are shown in Table 4 below. It is clearly seen that the amount of bitumen binder

increases as the gradation gets finer. In other word, as

the aggregate gradation gets coarser, lower amount of

bitumen binder is required. This is basically due to

the fact that the amount of fine aggregates gets higher

from G1 to G3. Fine aggregates contribute to a much

higher surface area which prepares a bigger area for

the bitumen binder to coat all the aggregates and

eventually necessitates a higher usage of binder.

The coefficient of determination (r2) represents the

percent of the data that is the closest to the line of

best fit. Table 4 also shows the target binder or the

optimum binder (OB) that is going to be used in this

investigation based on the BDT done. The OB

percentage obtained shows a relatively good results

based on the calculated r2.

Table 4: Target Binder (TB) and coefficient of determination (r2) for 3 different gradations

TB1

(%)

TB2

(%)

TB3

(%)

Average

TB (%)

r2

G1 2.75 2.75 2.50 2.67 0.9086

G2 3.30 3.40 3.20 3.30 0.8968

G3 3.80 3.85 3.85 3.83 0.9046

5.2 Air Voids Test

Voids in total mix (VIM) is defined as the total

volume of the small pockets of air between the coated

aggregate particles throughout a compacted paving

mixture, expressed as a percent of the bulk volume of

the compacted paving mixture. The relationship

between aggregate gradations and VIM were established as shown in Figure 4 below. The line

connected the 3 aggregate gradations shows the mean

VIM of each group which varies from 28.3% –

32.8%. It can be seen that the aggregate gradations

significantly affected the changes of VIM. G3 which

represents the finest aggregate gradations shows a

much lower VIM compared to G1 which represents

the coarsest aggregate gradations. Thus it can be

concluded that, as the aggregate gradation gets

coarser, so does with the increment in VIM. A

conventional Porous Asphalt skeleton requires VIM between 18 – 25% which actually much lesser

compared to the desired VIM for the purpose of

Grouted Macadam wearing coarse which is between

25% - 32% (REAM, Zoorob S.E). The high

percentage of air voids is required in order to allow a

full penetration of fluid grout by gravitational force.

Figure 4: VIM and Average Value of 3 Different Aggregate Gradations

5.3 Bulk Density (Gmb)

Bulk density or bulk specific density of a Marshall

sample is defined as the ratio of the mass in air of a

unit volume of a permeable material (including both

permeable and impermeable) at a stated temperature

to the mass in air (of equal density) of an equal

volume of gas-free distilled water at a stated

temperature. Figure 5 shows clearly the effect of Gmb

towards the changes of aggregate gradations. Gmb

were found to be inversely related with the changes

of air voids from the 3 different gradations. Referring

to both Figure 4 and 5, Gmb has shown a close

relationship with VIM. It is proven that due to

densification of the mix resulted in a reduction of

VIM and vice versa. The line connected the 3

aggregate gradation shows the mean Gmb of each

group which varies from 1.68 to 1.80 g/ml. Previous

studies done on Porous Asphalt for the preparation of

Grouted Macadam shows similar values with the

current investigation (Zoorob S.E). This is basically has proven that the chosen Porous Mix gradations are

suitable and acceptable for the current investigation.

Figure 5: Bulk Density of 3 Different Aggregate Gradations

6

5.4 Indirect Tensile Test – Resilience Modulus

Figure 6: Resilience Modulus of 2 Different Aggregate Gradations

IDT is a form of test which referring to resilience

modulus is a property of materials that absorbs

energy when it is deformed elastically and upon

unloading to this energy recovered. The greater the

resilience modulus, the stiffer the material gets, thus

higher in resisting deformation. The relationship

between aggregate gradations and resilience modulus

were established as shown in Figure 6 above. The

line connected both aggregate gradation shows the

mean value of each group which varies from 2584 –

2483 MPa. It is clearly shown that aggregate gradations do not affect significantly towards

resilience modulus but at the same time gives a

reasonably high value towards the production of

Grouted Macadam wearing coarse. G1 on the other

hand is not inserted in this test due to the very high

porosity of mix which made the sample breaks during

testing. Point of aggregate contact in G1 is low and

eventually did not allow the structure to hold on one

another. Higher resilience modulus gives stiffer

material. This will basically lead to a better resistance

towards permanent deformation, thus improved the resistance towards rutting. It is clearly stated that

when the resilience modulus is at the highest, it

indicates that the stiffest material condition under a

recoverable deformation behavior. According to

AASHTO, 1993 Pavement Design Guide, higher

value in resilience modulus is most desirable to build

a less thick pavement which will still maintain its

structural integrity. Comparing to the previous

studies done, the current investigation shows a

relatively good in resilience modulus and can be

suggested as surfaced for heavy traffic road corridors.

6 CONCLUSION

Bitumen binder decreases as the aggregate gradations

get coarser. Finer aggregate gradations will give

lower porosity, higher in bulk density and higher in

resilience modulus and vice versa.

ACKNOWLEDGEMENTS

Grateful acknowledgment is made to Institute of Research Management and Consultancy (IPPP) of the

University of Malaya for funding this project under

grant no PS117/2008C.

References

Lister, N.W & Addis, R.R 1977. Field observation of rutting and their practical implications. Transport

Research Board No. 640: 28-34

Hassan K.E., Setyawan, A. Zoorob, S.E., (2002).

“Effect of Cementitious Grouts on the properties of

Semi-Flexible Bituminous Pavement” Proceedings

of the Fourth European Nottingham, United

Kingdom, 11-12 April, 113-120

Hassan, K.E., Cabrera, J.G. & Head, M.K. 1998.

“The influence of aggregate characteristics on the properties of high performance high strength

concrete” In B.V. Rangan & A.K. Patnaik (eds),

Proceeding of the international conference: high

performance high strength concrete, 441-445, Perth,

Australia

Suresha S.N., George Varghese, & Ravi Shankar

A.U. (2009) “Characterization of porous friction course mixes for different Marshall compaction

efforts” Construction and Building Materials 23

Journal, (2009), pp. 2887-2893.

Huber G. Performance survey on open-graded

friction course mixes. Synthesis of highway practice

284. National cooperative highway research program.

Washington (DC) : Transportation Research Board;

2000.

ASTM D 7064/D 7064M. Standard practice for open-

graded friction course (OGFC) mix design. West

Conshohocken (PA); 2008

ASTM D 3203-91 Test Method for Percent Air Voids in Compacted Dense and Open Bituminous Paving

Mixtures

ASTM D 4123-82 (1987) Test Method for Indirect

Tension Test for Resilient Modulus of Bituminous

Mixtures

Road Engineering Association of Malaysia (REAM)

Semi Rigid Wearing Coarse Specification, (2007)

7

AASHTO GDPS-4 Guide for Pavement Design of

Pavement Structures (1993)

Fabb T.R.J. (1993) “The case for the use of Porous

Asphalt in the UK” Institute of Asphalt Technology

Yearbook (1993), pp. 46 – 59.

Hamzah M.O., Samat M. M., Joon K.H., Muniandy

R. (2004) “Modification of aggregate grading for

porous asphalt” 3rd Eurasphaly & Eurobotume

Congress. Vienna 2004 – Paper 196

Wright, P.H., and Dixon, K.K. (2004). Highway

Engineering. 7th ed, United State of America, John

Wiley & Son, Inc.

Zoorob S.E., Hassan K.E., Satyawan A. (2002)

“Effect of Cementitious Grouts on the Properties of

Semi-Flexible Bituminous Pavements” Proceeding of

the Forth European Symposium on Performance of

Bituminous and Hydraulic Materials in Pavements.

Nothingham, United Kingdom, 11-12 April, pp 112-

120

Der-Hsien Shen, Chia-Ming Wu, Jia-Chong Du

“Performance evaluation of porous asphalt with

granulated synthetic lightweight aggregate”

Construction and Building Materials, Volume 22,

Issue 5, May 2008, Pages 902-910

Cheuk Ching Wong, Wing-gun Wong “Effect of

crumb rubber modifiers on high temperature

susceptibility of wearing course mixtures”

Construction and Building Materials, Volume 21,

Issue 8, August 2007, Pages 1741-1745

S.N. Suresha, George Varghese, A.U. Ravi Shankar

“A comparative study on properties of porous friction course mixes with neat bitumen and modified

binders” Construction and Building Materials,

Volume 23, Issue 3, March 2009, Pages 1211-1217

Cheuk Ching Wong, Wing-gun Wong “Effect of

crumb rubber modifiers on high temperature

susceptibility of wearing course mixtures”

Construction and Building Materials, Volume 21,

Issue 8, August 2007, Pages 1741-1745

Liseane P.T.L. Fontes, Glicério Trichês, Jorge C.

Pais, Paulo A.A. Pereira “Evaluating permanent

deformation in asphalt rubber mixtures”

Construction and Building Materials, Volume 24,

Issue 7, July 2010, Pages 1193-1200

S.E. Zoorob, J.G. Cabrera and S. Takahashi (1999),

“Effect of Aggregate Gradation and Binder Type on

the Properties of Porous Asphalt” Proc. 3rd European

Symposium, Performance and Durability of

Bituminous Materials and Hydraulic Stabilised

Composites, Leeds, April, pp 145-162

Woodsie A.R., Woodward W.D.H., Baird J.K. “A

Critical Appraisal On The Performance Of Porous

Asphalt” Highway Engineering Reasearch Centre of

the Built Environment, University of Ulster, Bardon

Roadstone.

Subagio B.S., Karsaman R.H. “Laboratory

Performance Of Porous Asphalt Mixture Using Tafpack Super” Journal of the Eastern Asia Society

for Transportation Studies (EASTS), Vol.5, October

2003.

Beale J.M., You Z., “The Mechanical Properties of

Asphalt Mixtures with Recycled Concrete

Aggregates” Journal of Construction and Building

Materials (2009).

1

EFFECTS OF WASTE COOKING OIL AS A REJUVENATING AGENT FOR AGED BITUMINOUS PAVEMENT Hallizza Asli Postgraduate Student Email: halli_izza@yahoo.com Mohamed Rehan Karim Professor Email: rehan@um.edu.my ABSTRACT: Combination of oxidation and volatility are the main cause in changing the physical properties of bituminous pavement. Ageing process leads to hardening and caused the road failures especially cracking and rutting predictably occurred. In this paper, the possibility of using waste cooking oil as a rejuvenating agent for aged bitumen is investigated. In addition, the parameters that would influence the performance of the new rejuvenating agent developed by using waste cooking oil are initially considered. Unconventional method which is simulation of aging process in laboratory is prepared by using propeller mixer at fixed temperature, 160°C with different reaction times and speeds. The aged bitumen group that conducted in this research are 60/70, 50/60, 40/50 and 30/40 which have penetrations between of 60 to 70, 50 to 60, 40 to 50 and 30 to 40, respectively. The binder tests that involved in this research are Penetration Test, Softening Point Test which is well known as Ring and Ball Test, Brookfield Viscosity Test and Dynamic Shear Rheometer, (DSR) Test with the purpose of verifying the physical characterisation of bitumen binder for five different percentages mix of waste cooking oil. The waste cooking oil exhibited a significantly as the rejuvenator in the recycling asphalt pavement. The results indicate that the aged bitumen will be rejuvenated by the waste cooking oil due to changes in increasing of lower penetration value that similar as its original bitumen (Fresh Bitumen). Keywords: Rejuvenating agent, Waste cooking oil, Physical properties, Rheological Characteristics, Viscosity properties, Aged bitumen

1. INTRODUCTION

Decreasing supplies of locally available quality aggregate in many regions around the world, growing concern over waste disposal, and the rising cost of bitumen binder have resulted in greater use of reclaimed asphalt pavement (RAP) for road construction. Recycling Hot Mix Asphalt (HMA) is the process in which reclaimed asphalt pavement (RAP) materials are combined with new materials (the virgin aggregates and asphalt binder) and a rejuvenating agent to produce HMA mixtures. Recycled HMA mixtures, properly designed, must have similar properties to those of conventional HMA, fulfilling the same technical prescriptions that are demanded for conventional ones. Experience has indicated that the recycling of asphalt pavements is a beneficial approach from technical, economical, and environmental perspectives (Chen et al. 2007 and Romera et al. 2006).

Waste cooking oil was indicated as rejuvenator as well as one of the recycling agent that possible to improve the aged bitumen properties as similar level as the virgin bitumen. Researchers have proved that using rejuvenator in aged bitumen binder can reach target PG grades when the optimum percentage of rejuvenator is achieved. This research work will investigate the possibility of using

waste cooking oil as recycling/rejuvenating agent to restore the aged bitumen to a condition that resemble of the virgin bitumen. A rejuvenating agent that is commonly used is a low viscosity product obtained from crude oil distillation. The use of waste cooking oil is sought to provide an alternative rejuvenating agent, and to provide an agent that is considered as natural waste product. Incorporating a waste product instead of a petroleum product offers a potentially more sustainable product, and may lead to price and supply advantages.

2. MATERIALS AND EXPERIMENTAL

2.1. Materials

Bitumen of penetration grade of 80/100 is used in this research representing most popular usage in Malaysia. An accelerated ageing process on the virgin bitumen was carry out in laboratory by using propeller mixer to obtain different group of aged bitumen: aged bitumen grade 60/70, aged bitumen grade 50/60, aged bitumen grade 40/50 and aged bitumen grade 30/40 that have penetration in range of 60 to 70, 50 to 60, 40 to 50 and 30 to 40, respectively.

2

As mentioned earlier, rejuvenator that used in this study was waste cooking oil that easily acquired from the residential houses or restaurants. The waste cooking oil has low viscosity rather than aged bitumen. The fresh bitumen will be compared to rejuvenated bitumen by adding the aged bitumen with various percentages of waste cooking oil which are 1%, 2%, 3%, 4% and 5%. The waste cooking oil is mixed with the aged bitumen simultaneously by propeller mixer for 15 minute each percentage for every condition by 200 revolutions per minute at fixed temperature, 160°C. 2.2. Experimental 2.2.1. Development of Propeller Mixer Ageing Method

Propeller mixer is one of the laboratory equipment that utilised as a simulation unconventional method to ageing the bitumen. The original bitumen is heated in the oven for 160°C about one hour to one hour an half. Then, placed it on the hot plate and stir it using the propeller mixer for different reaction time with 300 and 350 revolutions per minutes mixing speed (300 and 350 rpm). Try and error process of reaction times have to be concerned to obtain the different aged group of bitumen. Reaction times by between four hours to seven hours is possible to be considered in this research. 2.2.2. Penetration Test (ASTM D5-97) The purpose of this test is to examine the consistency of a sample of bitumen by determining the distance in tenths of a millimetre that a standard needle vertically penetrates the bitumen specimen under known conditions of loading, time and temperature. The penetration test is simply a mean for grading bitumen at ambience temperature. This test is carried out under laboratory condition at 25°C, and the purpose of this experiment is to determine the depth that a weighted needle sinks into a bitumen specimen within 5 seconds. 2.2.3. Softening Point Test (ASTM D36-95) Two horizontal disks of bitumen, cast in shouldered brass rings, are heated at a controlled rate in a liquid bath while each supports a steel ball. The softening point is reported as the mean of the temperatures at which the two disks soften enough to allow each ball, enveloped in bitumen, to fall at certain distance. To determine the softening point of bitumen within the range 30°C to 157°C by means of the Ring-and-Ball apparatus. 2.2.4. Brookfield Viscosity Test (ASTM D4402-87) The Brookfield Thermosel Viscometer described in this procedure can be used to measure the viscosity of asphalt at elevated temperatures. The torque on a spindle rotating in a special thermostatically control sample holder containing a small sample of asphalt is used to measure the relative resistance to rotation. A factor is applied to the

torque dial reading to yield the viscosity of the asphalt in millipascal seconds. This test method can be used to measure the apparent viscosity of asphalt at application temperatures. 2.2.5. Dynamic Shear Rheometer Test (ASTM D – 4 Proposal P246) A Dynamic Shear Rheometer (DSR) may be used to determine the rheological properties of bituminous binders and it is generally assumed that a DSR can accurately measure binder properties over a wide range of conditions. Bitumen binders in the medium to high temperature range behave partly like an elastic solid (deformation due to loading is recoverable, it is able to return to its original shape after a load is removed) and a viscous liquid (deformation due to loading is non recoverable, it cannot return to its original shape after a load is removed). By measuring G* and δ, the DSR is able to determine the total complex shear modulus as well as its elastic and viscous components. The basic DSR test uses a thin bitumen binder sample sandwiched between two plates. The lower plate is fixed while the upper plate oscillates back and forth across the sample at 1.59 Hz to create a shearing action. These oscillations at 1.59 Hz (10 radians/sec) are meant to simulate the shearing action corresponding to a traffic speed of about 90 km/hr (55 mph) (Roberts et al., 1996). 3. RESULTS AND DISCUSSION

3.1. Influence of percentage of waste cooking oil on the penetration

Fig. 1. Comparison graph of penetration value, (dmm) against percentage of waste cooking oil, (%) for aged bitumen grade 60/70, 50/60, 40/50 and 30/40

In this study, penetration test was applied to examine the consistency of bitumen sample which is specifically was the hardness of the bitumen. In term of engineering, consistency is an empirical measure of the resistance offered by a fluid to continuous deformation when it is subjected to shearing stress. In Figure 1, increasing of penetration value for each different group of aged bitumen is caused by the chemical reaction when different percentage of waste cooking oil is added into it and it is obviously illustrated from the graph below. But, when it

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FRESH BITUMENAGED BITUMEN 60/70AGED BITUMEN 50/60AGED BITUMEN 40/50AGED BITUMEN 30/40

3

reached for certain volume of waste cooking oil, the penetration value is as similar as the original bitumen.

As can be seen from the graph above, for aged bitumen grade of 30/40, approximately 4% added waste cooking oil is changed the brittle bitumen to soft bitumen as similar as fresh bitumen. When 3% of waste cooking oil is added into the aged bitumen grade 40/50, the penetration value is alike the original bitumen with the penetration value of 84. On the contrary, the penetration value for aged bitumen grade 60/70 and 50/60 is similar as the original bitumen after 1% of waste cooking oil is mixed together.

From the graph displayed above, it was apparently showed that the lower group of aged bitumen, the obvious transformation can be observed. Rejuvenating agent such as waste cooking oil can be used in order to decreasing the maintenance cost of exited asphalt pavement.

3.2. Influence of percentage waste cooking oil on the softening point

Contrasting some other substances (e.g water which changes from solid to liquid at 0°C) bituminous materials do not have an exact melting point. Instead, as the temperatures rises, these materials slowly change from brittle or very thick and slowly-flowing materials to softer and less viscous liquids.

Fig. 2. Comparison graph of softening point Temperature, (°C) against percentage of waste cooking oil, (%) for aged bitumen grade 60/70, 50/60, 40/50 and 30/40.

The effects of percentage of waste cooking oil and softening point value of different aged bitumen group: aged bitumen grade 60/70, aged bitumen grade 50/60, aged bitumen grade 40/50 and aged bitumen grade 30/40 were presented in figure 2. As illustrated from the graph, when the group of aged bitumen is decreasing with the penetration value, the softening point is increased. For aged bitumen without waste cooking oil for grade 30/40, the softening point is 54°C but for grade 40/50, the bitumen melted at 50°C meanwhile for grade 50/60 and grade 60/70 is 49°C. Instead, the higher percentage of waste cooking oil added into the aged bitumen group, the lower softening point temperature is obtained. For aged bitumen grade 60/70 and 50/60, 1% of added waste

cooking oil caused it to returns to the original value. On the contrary, the original value of bitumen was achieved when 3% of waste cooking oil added into aged bitumen grade 40/50 which is 46°C. Meanwhile, the softening point of aged bitumen grade 30/40 is similar as the fresh bitumen when 4% of waste cooking oil is added.

As can be seen in the figure 2, the softening point value is diminishing gradually. With the increasing of aging time, the penetration value is decreased but softening point temperature is increased due to oxidation reactions happened and more asphaltenese micelles appeared. Increasing of asphaltenese content with high molecular weight was produced harder bitumen. The chemical reaction and mixture of waste cooking oil was rejuvenating the diverse groups of aged bitumen.

3.3 Influence of percentage waste cooking oil on the viscosity

This test is significantly to ensure that the binders are sufficiently fluid when being pumped and mixed at the hot mix plants. As compared with the capillary tube viscometers, the rotational viscometer provides larger clearances between the components. Therefore, it can be used to test modified asphalts containing larger particles, which could plug up a capillary viscometer tube. Another advantage of the rotational viscometer is that the shear stress versus shear rate characteristics of a test binder can be characterised over a wide range of stress or strain levels. For Superpave binder specification purpose, the rotational viscosity test is to be run at standard temperature, 135 °C to ensure proper workability during mixing and placement. Critical condition of an asphalt concrete is at the highest pavement temperature at which the asphalt mixture is the weakest and most susceptible to plastic flow when stressed. When the other factors are kept constant, an increase in the viscosity of the asphalt binder will increase the shear strength and subsequently the resistance to plastic flow of the asphalt concrete. With respect to resistance to plastic flow of the asphalt concrete, it is preferable to have a high asphalt viscosity at the highest anticipated pavement temperature.

The effectiveness of the mixing of asphalt cement and aggregate, and the effectiveness of the placement and compaction of the hot asphalt mix are affected greatly by the viscosity of the asphalt. The result of viscosity towards the elevated temperature is reported in figure 3 as the following below. In this study, elevated temperature of 90°C, 110°C, 130°C, 135°C, 150°C and 170°C is concerned. As can be seen from the illustrated figure 3 showed the high temperature viscosity relationships with the different percentage of waste cooking oil to the different grade of aged bitumen: 60/70, 50/60, 40/50 and 30/40 which is to be compared to original bitumen grade 80/100. According to Sengoz and Isikyakar (2008), the increase in viscosity is not favorable because the bitumen with high viscosity levels require higher mixing, laying and compaction temperatures which results in too much energy consumption.

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FRESH BITUMENAGED BITUMEN 60/70AGED BITUMEN 50/60AGED BITUMEN 40/50AGED BITUMEN 30/40

4

Fig. 3. Viscosity (MPa) versus temperature for fresh bitumen and optimum percentage of waste cooking oil added to aged bitumen grade 60/70, 50/60, 40/50 and 30/40 As to the Brookfield viscosity is increasing from 90°C to 170°C, the results in figure 3 clearly showed the decreasing in viscosity due to higher waste cooking oil contents. For aged bitumen grade 60/70 and grade 50/60, as can be seen from the graph, the line of fresh bitumen is overlapped with the 1% added of waste cooking oil. It showed that adding the 1% of waste cooking oil achieved the rejuvenated bitumen. Meanwhile, range of 3% to 4% of waste cooking oil is obtained from the aged bitumen grade 40/50 to be similar as the original bitumen. On the contrary, for grade 30/40 of aged bitumen, within the range waste cooking oil content of 4% to 5% is slightly overlapped to the line of fresh bitumen. Other line for each test condition for diverse grade of aged bitumen is shift out from the line of the original bitumen. From the Brookfield viscosity test, it was obviously an additional proved that waste cooking oil can be used as the rejuvenating agent for aged bitumen in addition to softening point test and penetration test

3.4 Influence of percentage waste cooking oil on the rheology

When testing bitumen with the DSR tester according to the Superpave specification, the sample is sandwiched between a fixed-base plate and an oscillating spindle plate. The stress–strain pattern is recorded. The angular frequency, which is varied in many other types of test, is fixed at 10 rad s-1 in the Superpave specification, which can be attributed to the loading time within a pavement where vehicles travel at 90 km/h. As binders get older, they become more stiff and brittle. It is generally accepted that bitumen hardening in the field is mostly due to oxidation. It has also been recognised that the reactions taking place in bitumen exposed to the air at low and high temperatures are different. Thus rutting is a more significant problem at the beginning of the service life of a pavement, and the low-temperature cracking and fatigue failure are more serious problems towards the end of the service life of a pavement.

Figure below showed result of dynamic shear rheometer test for aged bitumen grade 60/70, 50/60, 40/50 and 30/40. The rheological properties of aged for each group of aged bitumen with five different percentage of added waste cooking oil are compared to original bitumen (80/100). Behaviour of asphalt binders can be showed by plotting master curves of the complex modulus vs. temperature. Figure 4 plot G* vs. temperature at 10 rad/s for different aged bitumen group with optimum waste cooking oil content and fresh bitumen. As the temperature increases, the modulus decreases significantly. Aged bitumen grade 60/70, 50/60, 40/50 and 30/40 without adding waste cooking oil was the stiffest over the entire range of temperatures, but after adding waste cooking oil from 1% to 5%, the modified binder become soft due to decreasing of modulus value. The modulus for these binders does not change as dramatically as the temperature changes compared to the other modified binders. As we can be seen, the graph curve of 1% added waste cooking oil for aged bitumen grade 60/70 and 50/60 is the nearest due to the fresh bitumen curve. On the contrary, when 3% and 4% is mixed to the aged bitumen grade 40/50 and 30/40 it seems to be as similar as original bitumen, respectively.

Fig. 4. Complex shear modulus, G* (Pa) versus temperature for Fresh Bitumen and optimum percentage of waste cooking oil added to to aged bitumen grade 60/70, 50/60, 40/50 and 30/40 Phase angle, δ (°) is the phase difference between the stress and strain in an oscillatory deformation and is a measure of the viscoelastic character of the material. If δ is equals to 90°, then the binder can be considered purely viscous in nature and when the δ is equal to 0° would represent an ideal elastic solid. The ability of the binders to store deformational energy at high temperatures and to dissipate deformational energy through flow at low temperatures is called elasticity and flexibility, respectively. In this study, phase angle as a function of elevated temperatures were determined for all the condition at 10 rad s-l (1.59 Hz) over a temperature range of 30 to 80°C. As can be seen graph from the figure 5, at a fixed frequency and at temperatures that higher than about 65°C the phase angle of all the modified bitumen approaches 90°. In this case, the stored energy per cycle of deformation becomes negligible compared to that

R² = 0.9477

R² = 0.9475R² = 0.9465

R² = 0.9427R² = 0.9423

-10000

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FRESH BITUMEN60/70 + 1% WCO50/60 + 1% WCO40/50 + 3% WCO30/40 + 4% WCO

R² = 0.991R² = 0.9917

R² = 0.9994 R² = 0.9918R² = 0.990

250005000075000

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5

dissipated as heat. The rejuvenated bitumen curve showed the identical pattern as the virgin bitumen.

Fig. 5. Phase angle, δ (°) versus temperature for Fresh Bitumen and optimum percentage of waste cooking oil added to to aged bitumen grade 60/70, 50/60, 40/50 and 30/40 4. CONCLUSIONS

As the conclusion, waste cooking oil (waste material) is found to be a suitable rejuvenating agent for aged bitumen in asphalt pavements. By using waste cooking oil as bitumen rejuvenator in recycled asphalt pavements, it significantly contributes to the reduction in environmental degradation. In addition, recycling asphalt pavements reduces the use of virgin materials (natural rocks, bitumen from petroleum).

ACKNOWLEDGEMENT

This study is a part of research project that sponsored by the Institute of Research Management and Consultancy, University of Malaya as the financial assistance by awarding the grant PS138/2009B to accomplish the present and ongoing work. And it is an honour to have Kajang Rock Sdn. Bdn. as a cooperative supplier of bitumen 80/100.

REFERENCES

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Airey, D.G. and Rahimzadeh, B. (2004). Combined

bituminous binder and mixture linear rheological properties. Construction and Building Material, 18: 535-548.

Chen, J.S., Huang, C.C., Chu, P.Y. and Lin, K.Y.

(2007). Engineering characterization of recycled asphalt concrete and aged bitumen mixed recycling agent. Journal of Materials Science, 42:9867–9876.p

Doh, Y.S., Amirkhanian, S.N. and Kim, K.W. (2008). Analysis of unbalanced binder oxidation level in recycled asphalt mixture using GPC. Construction and Building Material 22: 1253-1260.

Lu, X.H. and Isacsson, U (1997). Chemical and rheological evaluation of ageing properties of SBS polymer modified bitumens. Fuel, S0016-2361: 00283-4.

Lu, X.H. and Isacsson, U (2002). Effect of ageing on

bitumen chemistry and rheology. Construction and Building Material, 16(1): 15-22.

Lu, X.H. and Isacsson, U (1996). Rheological

characterisation of styrene-butadiene-styrene copolymer modified bitumens. Construction and Building Material, S0950-0618: 00033-5.

Lee, S.J., Amirkhanian, S.N., Park, N.W. and Kim, K.W.

(2009). Characterization of warm mix asphalt binders containing artificially long-term aged binders. Construction and Building Material, 23: 2371-2379.

Roberts, F.L., Kandhal, P.S., Brown, E.R., Lee, D-Y,

Kennedy, T.W., Hot Mix Asphalt Materials, Mixture design and Construction, Text Book, NAPA Education Foundation Lanham Maryland, second edition, 1996.

Romera, R., Santamaria, A., Pena, J.J., Munoz, M.E.,

Barral, M., Garcia, E. and Janez, V. (2006). Rheological aspects of the rejuvenation of aged bitumen. Rheol Acta, 45: 474-478.

Saleh, M.F. (2006). Experimental investigation of bitumen

physical properties on foamability and mechanical properties of foam bitumen stabilized mixes. Third Gurl Conference on Roads, March 6-8: 92-98.

Sengoz, B. and Isikyakar, G. (2008). Analysis of styrene-

butadiene-styrene polymer modified bitumen using fluorescent microscopy and conventional test methods. Journal of Hazardous Materials. 150: 424–432

Shen, J., Amirkhanian, S.N. and Tang, B. (2007). Effects

of rejuvenator on performance-based properties of rejuvenated asphalt binder and mixtures. Construction and Building Material, 21: 958-964.

Wu. S., Cong, P., Yu, J., Luo, X. and Mo, L. (2006).

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Wu, S.P., Pang, L., Mo, L.T., Chen, Y.C. and Zhu, G.J.

(2009). Influence of aging on the evolution of structure, morphology and rheology of base and SBS modified bitumen. Construction and Building Material, 23: 1005-1010.

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)

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1

ENGINEERING PROPERTIES OF LOCAL RECLAIMED ASPHALT PAVEMENT AGGREGATE

Lillian Gungat1, Jodin Makinda

1 and Liew Yu Li

2

1 School of Engineering & IT, Universiti Malaysia Sabah, Sabah

E-mail:lillian@ums.edu.com.my

2DH Perunding, Kota Kinabalu, Sabah

ABSTRACT: Reclaimed asphalt pavement (RAP) as an alternative material in road construction is not a new issue as it is being

widely accepted in many countries compared to Malaysia. The use of RAP brings about many credit and advantages in term of

environment, cost, resources and engineering value. Thus give it a sustainable usage. In pavement design and construction, selection of

material influences the overall performance and quality. Therefore, engineering properties play important roles in maximizing the

usage of the material. In this study, the properties of RAP aggregate obtained from local roads were tested and evaluated to determine

its existing condition. The study covered the RAP aggregate physical properties such as grading and shape, and also its mechanical

resistance against impact and abrasion. Tests and investigation were done in accordance to the Public Work Department (JKR)

specification and standard applied such as BS, ASTM and ASSHTO. Comparison and evaluation were done based on the original

initial properties and the road conditions such as traffic data, age and location. Results showed that tested RAP aggregate properties are

still within the pavement material limit range with some degradation. Traffic condition and pavement age found to be the main

influencing factors for the mechanical properties deprivation. Investigation findings showed that the RAP aggregate still possess good

quality properties to be used as an alternative resource in road construction.

Keyword: Reclaimed Asphalt Pavement (RAP), Aggregate, physical properties, Impact and Abrasion

1. INTRODUCTION

Reclaimed Asphalt Pavement (RAP) utilization as an

alternative material used since many years ago in

European countries compared to Malaysia. RAP is the

term use for remove or reprocessed asphalt pavement to

be used in road construction (Huang et al.,2005).

Researches have shown that RAP usage minimize the

dependency to the aggregate natural resources, saving

cost, energy and environment. Thus contributes to the

sustainable development in road construction.

In road construction, aggregate is the highest abundant

material used. In asphalt concrete pavement, aggregate

may constitute about 70-75 percent by volume or 90-95

percent by weight (Somayaji, 2001). Aggregate plays an

important role in sustaining the vehicle loads and

transferring it from the wearing surface to the foundation

in flexible pavement (Karim et al, 1991). Therefore the

aggregate properties are very much influential to the

pavement behaviour and quality. A well understanding of

its engineering characteristic is important in maximizing

the usage and benefits. The principal factor that

determines the suitability of recyclable materials for use

in highway construction is their engineering properties

(Aribisala,2007). Engineering characteristic is the

property in term of physical, mechanical, and chemical

which will contribute and effect on the design and its

usage.

The most important aggregate properties in road

construction are the size of the aggregate and it’s grading.

This is important in order to obtain the maximum

compaction to achieve maximum dry density; which is

highly affected by the aggregate arrangement and the

amount of filler particle to form the best interlocking

layers. Based on the function and required characteristic,

appropriate grading will be selected and evaluated. Poor

aggregate grading may causes pavement deterioration

such as segregation, improper compaction and thus leads

to structure failures, surface defects and surface

deformations. Apart from that, geological factors

(composition, texture, particle shape, pores, etc.) also

affect the mechanical degradation and strength of

aggregates.

In Malaysia, various recycling techniques are adopted for

rehabilitation work of flexible pavement (Ahmad et. Al,

2004). The stabilized RAP recently used for road

maintenance in Sabah showed good performance and yet

fast construction, saving cost, labour and environment

(Stabilised Pavement Malaysia,2007). This indicates that

RAP has the potential as an alternative resource in road

construction. Therefore, further research on local

properties of RAP is needed. This study investigates the

physical and mechanical properties of RAP obtained from

three local roads.

2. MATERIALS AND METHOD

The reclaimed asphalt pavement samples were obtained

from selected site in Sabah which is under construction

for road maintenance. Three locations of road with

different classification were selected namely Jalan

Penampang, Jalan Bundusan-Lintas and Jalan Papar

Lama. The sample taken in various chainages to ensure

the RAP samples are not influenced by the surrounding.

Due to the sample taken is a used material, studies of its

background history is important as it will influences the

2

aggregate properties. Figure 1 and Table 1 show the used

Asphalt pavement and road data respectively.

Fig. 1. Stockpile of Used Asphalt Pavement at Jalan

Bundusan-Lintas.

Table 1. Road Data And Parameters

Description Road Location

Jalan

Penampang

Jalan

Bundusan

Jalan Papar

Lama

Type State road State road Federal road

Age >5 yrs <5 yrs >20 yrs

Aggregate Class B Class B ACW 20

Average daily

traffic (ADT)

20511

15357

2623

Heavy

Vehicle (%)

<2%

(2007)

<2%

(2006)

>20%

(2007)

Source: JKR Sabah, 2008

Collected samples have to be processed prior laboratory

testing. The samples obtained from the site which in

coring form, were evaluated based on it instantaneous

appearance such as the thickness of the sample and clay

or silt soil content. Contaminants were washed and

cleaned from the RAP sample. Samples were then heated

in oven and hot plate to obtain a loose aggregate sample

coated with bitumen. Parameters such as boiling

temperature not to exceed the bitumen flash point and

heating duration were taken into account to minimize

error and to obtain consistency during the sample

preparation. After that, laboratory testing were conducted

to evaluate the physical properties; size grading, water

absorption and flakiness and mechanical properties;

abrasion and impact value The obtained tests results were

compared to the standard specification which is specified

in Malaysian Standard, British Standards American

Standard Testing of Materials (ASTM) and the American

Association of State Highway and Transportation Officers

(AASHTO) and correlated to the local pavement design

(JKR, 1990).

3. RESULTS AND DISCUSSIONS

3.1 Sieve Analysis

The gradation obtained for all the three samples were

plotted in the specification grading limits range

respectively shown in figure 2, figure 3 and figure 4.

Fig. 2. Specification Grading for Jalan Bundusan-Lintas,

Class ‘B’.

Fig. 3. Specification Grading for Jalan Penampang, Class ‘B’.

Both Jalan Bundusan and Penampang RAP samples fall

within the aggregate limit range with uniform aggregate

particles. Jalan Bundusan sample contains maximum

percentage of particle range within the size of 4.75mm,

2.36mm and 600 m sieve. From the size distribution

analysis, more than 65% passes the 4.75mm sieve

opening which indicate most of the particle are fine grain

aggregate. Similar pattern is observed for Jalan

Penampang. However, this sample contained more coarse

aggregate compared to Jalan Bundusan sample.

Specification Grading Limits for Wearing Course,

Class 'B', Jalan Bundusan-Lintas

0

20

40

60

80

100

120

0.01 1 100

Sieve Size (log)

Pe

rce

nta

ge

Pa

ss

ing

(%

)

RAP Sample

Jalan Bundusan-

Lintas

Minimum Grading

for Class 'B'

Maximum Grading

for Class 'B'

Specification Grading Limits for Wearing Course 'B',

Jalan Penampang

0

20

40

60

80

100

120

0.01 0.1 1 10 100 1000

Sieve Size (log)

Perc

en

tag

e P

assin

g (

%)

RAP sample Jalan

Simpang Lido

Minimum Grading

for Class 'B'

Maximum Grading

for Class 'B'

3

Fig. 4. Graph of Specification Grading for Jalan Papar Lama,

AWC-20.

Whereas for Jalan Papar Lama sample it shows a poorly

or gap graded curve, compared to the standard AWC-20

gradation. The sieve size opening of 3.35mm with a low

weight of percentage indicate it as the missing size. The

nominal size is between 5mm and 4.25mm aggregate with

the highest weight percentage of 32.18% and 30.62%

respectively. The results obtained fall outside the

specification range limit. Both the coarse and fine grain

showed a poor graded sample. This indicates that the

Jalan Papar Lama RAP aggregate gradation is totally out

of the boundary of the standard specification required.

The test results of this sieve analysis showed some

degradation in RAP aggregate due to fraction and break

down of the aggregate during the scraping of the

pavement. The nominal size of the aggregate basically

falls between 5mm to 2mm size. Aggregates are subjected

to impact stresses during handling, processing, and

compaction and repeated stresses during the service life of

a pavement. The fracture of the coarse aggregate into

smaller grain aggregate explains the abundant of this size

particle. Due to the heating process and spread drying, the

fine aggregate such as those 150 m and 75 m tends to

stick together because of the existing bitumen coating,

and forming a group of slightly bigger than its size. This

explains the low percentage of aggregate within this size.

The age of the RAP sample is also affected the grading of

the aggregate as the older sample tends to have more

fracture particle due to its impact during service and

degradation of the sample. This proves the poorly graded

of Jalan Papar Lama sample with the age more than 20

years compared to the other two samples. Additionally,

the usage of the roads with percentage of heavy vehicle

worsens the road condition.

3.2 Flakiness Index

Table 2 shows the Flakiness Index of the RAP samples.

Both the state road (Jalan Bundusan and Jalan

Penampang) shares a near value of 30, and compared to

its standard specification of 35, it is still under the

requirement limit. As for Jalan Papar Lama, smaller result

of flakiness index might caused by the degradation of size

particle due to fracture and break down process. Overall,

the entire samples still possess reasonable FI values and

lower than the standard specification.

Table 2. RAP Aggregate Flakiness Index (FI)

Sample location Flakiness Index (FI)

Jalan Bundusan 30.11

Jalan Penampang 31.81

Jalan Papar Lama 26.57

3.3 Water Absoprtion

The water absorption results are shown in Table 3.

Compared to its initial test result, some percentage drop

are observed but still less than 2% and satisfied the

standard requirement. Bitumen is a hydrocarbon material

and it behaves as a hydrophobic. Therefore, the bitumen

coating decrease the water absorption, thus results in low

water absorption percentage. This also explains the lesser

percentage drop when the age of the sample increases

Table 3. RAP Aggregate Water Absorption

Sample

Location

Water Absorption Percent Drop

(%) Initial

(Virgin Aggregate)

(%)

RAP

(%)

Jalan

Bundusan

1.23 0.70 43

Jalan

Penampang

1.23 0.96 22

Jalan Papar

Lama

1.37 1.11 19

3.4 Los Angeles Abrasion (LAAV) and Impact

Value (IV)

The results for all three samples of roads indicated the

various properties differ due to the different existing

condition and situation as shown in Table 4. Jalan Papar

Lama shows the least mechanical strength with the

highest abrasion wear and aggregate impact value of

26.94 and 43.81 respectively. Jalan Bundusan is the

strongest among all three sample with 14.61 for AIV and

30.26. As for Jalan Penampang, it falls between the two

samples with 15.78 for AIV and 33.07 for LAAV. Both

the state road has a very close value, as the existing

condition does not vary much. The longer period of life

time service explains the weak condition of the RAP

aggregate sample from Jalan Papar Lama as compared to

Jalan Penampang and Jalan Bundusan-Lintas.

Specification Grading Limits for Wearing Coarse

AWC-20, Jalan Papar Lama

0

20

40

60

80

100

120

0.01 1 100

Sieve Size (log)

Pe

rce

nta

ge

Pa

ss

ing

(%

)

RAP sample Jalan

Papar Lama

Minimum Grading

for AWC-20

Maximum Grading

for AWC-20

4

Table 4. Aggregate Los Angeles Abrasion (LAAV) and

Aggregate Impact Value (IV)

Sample location LAAV IV

Jalan Bundusan 30.26 14.61

Jalan Penampang 33.07 15.78

Jalan Papar Lama 43.81 26.94

Additionally, the traffic volume shown in Table 1 also

influences the sample strength, as the traffic indicates how

much load the road accommodates. The differences in

both the state road can be explained due to the different

traffic volume, where Jalan Penampang carries more

volume than Jalan Bundusan. Furthermore, Jalan

Penampang service life is longer than Jalan Bundusan.

Therefore, Jalan Bundusan is slightly stronger compared

to Jalan Penampang. With the highest percentage of heavy

vehicle in Jalan Papar Lama; 20% in year 2000, whereas

only 2% in year 2007 recorded in Jalan Penampang, gives

it the worst condition compared to the other two

location’s sample.

Furthermore, the bitumen coating gives extra strength to

the aggregate to resist impact and tends to group up and

stick together. However, the bitumen properties tend to

weaken as the age increases. The old, harden RAP binder

as in Jalan Papar Lama does not possess the original good

quality anymore compared to Jalan Penampang and Jalan

Bundusan. . The bitumen coating in Jalan Penampang

and Jalan Bundusan tends to bind the sample together

when its heat up and give a better resistance.

3.5 Relationship between Physical and Mechanical

Properties of RAP

Through the obtained results, relationship between the

RAP aggregate properties can be identified. The variation

in resistance within the samples can be attributed to the

influence of aggregate particle shape and geological

features (Koukis et. al, 2007). The aggregate resistance

and geometrical properties; particularly the shape, are

linearly related. Due to the flakiness of the particle shape,

compaction results a higher void ratio and weaker

compound. This can be seen from the results of Jalan

Penampang and Jalan Bundusan. However, for sample

obtained from Jalan Papar Lama, ages and many other

factors influence the variation in the values obtained.

The water absorption reflects the volume of pore spaces

constitute significant geological factors influencing the

aggregate resistance. The durability, in term of resistance

to weathering to wear, generally increases with the

decreasing grain size and decreasing volume of pore

spaces. The increase in percentage water absorption is

related to an increase in LAAV and AIV results.

Additionally, the grading of the sample which still falls in

the grading limits, such as Jalan Penampang and Jalan

Bundusan, results in higher resistance value as compared

to Jalan Papar Lama.

4. CONCLUSION

Tests and evaluation have been conducted on the RAP

aggregate samples, and the following conclusions can be

drawn;

There is some degradation on the size

distribution of the RAP samples, but the

Flakiness Indexes of the samples are still under

the requirement specification.

Mechanical properties of the RAP samples show

some deprivation especially Jalan Papar Lama.

However, RAP samples of Jalan Penampang and

Jalan Bundusan still possessed strength within

the standard.

The RAP aggregate is influenced mostly by the

traffic condition and the pavement condition

especially the period of service. Therefore, the

existing condition is important and need to be

studied.

It can be seen that the RAP aggregates do have the

potential to be used as an alternative material in road

construction. With the aid of its engineering properties

understanding, maximizing the usage of RAP become an

advantage. However due to their various individual

characteristics, tests and evaluations should be conducted

to ensure proper usage of the material.

REFERENCES

Ahmad, J., Rahman, M. Y. A. & Din, K. (2004)

Degradation And Abrasion Of Reclaimed Asphalt

Pavement Aggregates. International Journal of

Engineering and Technology, 1: 139-145.

Aribisala, J.O. and Ogundipe, O.M. (2007) Recycled

Materials In Highway Construction For Sustainable

Development. Research Journal of Applied

Sciences., 2: 393-396.

Huang, B., Shu, X. & Li, G. (2005) Laboratory

investigation of Portland cement concrete containing

recycled asphalt pavements. Cement and Concrete

Research, 35: 2008-2013.

JKR 20407 0001-1990. Guidelines for Inspection and

Testing of Road Works, Jabatan Kerja Raya. Kuala

Lumpur.

Karim, M. R., Hamzah, M. O., & Hasan, A.(1991)

Pengenalan Pembinaan Jalan Raya Berbitumen.

Kuala Lumpur: Dewan Bahasa dan Pustaka.

Koukis, G., Sabatakakis, N., Spyropoulos, A. (2007)

Resistance Variation Of Low-Quality Aggregate.

Earth and Environmental Science, Vol. 66 (4): 457-

466.

5

Somayaji, S. (2001) Civil Engineering Materials, New

Jersey: Prentice Hall.

Stabilised Pavement Malaysia(SPM) Sdn. Bhd (2007).

Road Recycling & Stabilisation-The New Era of

Roads Construction in Sabah Malaysia, IEM

Seminar.

MODIFIED BITUMEN WITH OIL PALM FRUIT ASH

Gatot Rusbintardjo1,2, Mohd. Rosli Hainin2

1)Department of Civil Engineering and Environment, Faculty of Engineering, Universitas Islam Sultan Agung (UNISSULA) Semarang Email: gatotrsb@gmail.com; phone: +60177932890; +62247471703 2)Department of Geotechnical and Transportation Engineering, Faculty of Civil Engineering, Universiti Teknologi Malaysia Email: roslihainin@gmail.com; phone: +6013745050

ABSTRACT: Increased traffic factors such as heavier loads, higher traffic volume, and higher tire pressure as well as studded tire wear, demand higher performance pavements to prevent pavement distress. Some of these serious distresses include rutting, shoving, stripping, and fatigue cracking, which ultimately may lead to complete failure of the pavement. Such distresses reduce the performance of asphalt pavements, which not only cause inferior ride quality to motorists, but also yield higher life-cycle costs. Some of these problems are associated with the asphalt cement or bitumen as binders. The performance of asphalt pavements is mainly governed by the properties of the bitumen, because bitumen is the continuous matrix and only deformable component. At high temperatures (40 to 600C), asphalt exhibits a viscoelastic behaviour. Pavement made of bitumen may show distress when exposed to high temperatures. At elevated temperatures, permanent deformation (rutting) occurs and leads to channels in the direction of travel. This is attributed to the viscous flow of the bitumen matrix in paving mixtures, which retains strains induced by traffic. On the other hand, bitumen will brittle in low temperature and pavement cracking will occur. Therefore, pavement performance is strongly associated with the rheological properties of bitumen. Bitumen exposed to wide range of load and weather conditions, however, does not have good engineering properties, because it is soft in a hot environment and brittle in cold weather. To prevent occurring of pavement distress, it is important to reinforced bitumen to improve its mechanical properties. Modified bitumen with Oil Palm Fruit Ash (OPFASH) was studied by analyzing its rheological properties. The results which were reported in this paper show that OPFASH-Modified Bitumen can resist to high pavement temperature rutting up to 70°C, 10°C higher than average high pavement temperature. in addition also resist to intermediate pavement temperature fatigue cracking 20°C.

Keyword: Oil Palm Fruit Ash, Modifier, Bitumen, Rheology, Rutting, Cracking 1. INTRODUCTION Traditionally, a conventional binder such as bitumen penetration grade 80/100 was used in road pavement construction which also most use in Malaysia. However, increased traffic factors such as heavier loads, higher traffic volume, and higher tire pressure as well as studded tire wear, require the durability and strength of the binder to resist rutting, fatigue and cracking tendencies of the pavements. One means of achieving this is by modifying the bitumen. Modified bitumen with additive to strengthen the mechanical properties of the bitumen has been practiced in many forms for over 150 years but there is a renewed interest. Feasibility of using Oil Palm Fruit Ash (OPFASH) was evaluated in this research. OPFASH is by-product of palm oil mill, or the ash from burning mesocarp of fruitlets of the palm oil fruits. The idea to use OPFASH is to look for the alternative of other modifier instead of polymer, the most use of bitumen modifier, and to reduce environmental pollution caused by waste palm oil industry. Malaysia is the palm oil producing countries and the country’s largest palm oil industry in the world. Malaysia Palm Oil production in the year 2009 was 17.56 million tonnes1. From 1 kg of oil palm fruilets can be resulted 0.34 kg of crude palm oil (CPO)

and 0.1 kg Kernel Oil or totally resulted 0.44 kg of oil (Department of Environmental, Ministry of Science, Technology and the Environment Malaysia, (1999)). This means that from 1 kg of oil palm fruitlets resulted 0.56 kg of the mesocarp waste. If the product of palm oil in the year 2009 is 17.56 million tonnes (44% of the oil palm fruitlets), it is means that there are 9.83 million tonnes of the waste of mesocarp in the year 2009, large amount of waste that will pollute the environment if not used. 2. EXPERIMENTAL PROCEDURE 2.1 Materials The bitumen used in this study was 80/100 penetration grade source from PETRONAS. Oil Palm Fruit Ash (OPFASH) is by-product of palm oil mill, or the ash from burning mesocarp of fruitlets of the palm oil fruits. This by-product has been disposed as waste thus polluting the environment and affecting the health of community surrounding. Physically, OPFASH is grayish in colour and become dark with increasing proportions of unburned carbon. The physical properties and chemical composition of OPFASH were given in Table 1 and 2 respectively. From Palm Oil Mill OPFASH was in form of rough elongated-flat grains with maximum grains size length 6

mm. In order to be able to well mixed with the bitumen, OPFASH was grinded into the fine grains with uniform grains size 75µm or 0.075 mm. Table1. Physical Properties of OPFASH (Mohd. Warid)

Table 2 Chemical Composition of OPFASH (M. Warid)

2.2 Procedures 2.2.1 Sample preparation The amount of 1500 grams of 2.5% to 10% of OPFASH in increments of 2.5% by weight of bitumen were blended with bitumen using ordinary laboratory propeller mixer at mixing temperature 160 ± 5°C, mixing time 60 minutes, and mixing stirring speed 800 revolution per minute (rpm). Immediately after mixing being finished, amount of 300 grams were poured into 25.4 mm by 139.7 mm of aluminum tube to be used for storage stability test. The rest of the mixtures were kept into room temperature during three days for further aging test. 2.2.2 Storage stability test Storage stability test was conducted to evaluate the possible separation of OMB under storage. The test procedure was conducted in accordance to ASTM D5892. The test procedure was as follows: immediately after mixing being finished, OPFASH-modified bitumen was poured into 25.4-mm by 139.7-mm aluminum tube and heated to 165°C for 1 and 3 days in the oven. The selection of storage days was based on estimation of road construction delay. At the end of the test period, samples were placed in the freezer at -10°C for 4 hours to solidify the OMB. Upon removing the tube from the freezer, samples were cut into three equal

length portions with the spatula and hammer. Softening point (Tr&b) test was performed to the top and bottom samples. The Tr&b difference between top and bottom portions was used to evaluate OMB’s stability. 2.2.3 Rheology test using Dynamic Shear Rheometer

(DSR) The DSR was used to characterize the viscous and elastic behaviour of bitumen binders It did this by measuring the complex shear modulus |G*| and phase angle (δ) of bitumen binders Test was performed based on European Standard Test EN 14770, and was conducted on unaged, RTFO aged residue, and PAV aged residue, both for neat bitumen and OMB binders. Therefore, sample must be aged by using rolling thin film oven (RTFO) and pressure aging vessel before being performed DSR test however, the RTFO and PAV tests procedure were not described in this paper. There are two types of pavement distress can be measured by using of DSR, these were permanent deformation or rutting and fatigue cracking. 2.2.3.1 Permanent deformation (Rutting) The geometry of the equipment needed to measure |G*| and δ was shown in Figure 1.

Figure 1: Dynamic Shear Rheometer Geometry

Bitumen was sandwiched between the oscillating spindle and the fixed base. The spindle was oscillated back and forth using either a constant stress or constant strain. Constant stress means that the spindle was rotated through a certain distance until a fixed stress was achieved. Constant strain means that the spindle was rotated every time through a fixed distance, regardless of the stress achieved. While this rotation occurs, the resulting stress or strain was monitored. The relationship between the applied stress and the resulting strain provides information necessary to compute |G*| and δ. In this study, for rutting test were conducted at five different temperatures 50, 60, 65, 70, and 75°C, using stress controlled sweep, and at test frequency 1.59Hz. The binder to be tested were unaged, RTFO aged, and PAV aged residue.

2.2.3.2 Fatigue cracking Test procedure for fatigue cracking was similar to that of rutting test. The difference was only in the test temperature, test geometry, and test sweep controlled. Fatigue cracking was considered as a strain controlled. Test was conducted at five different temperatures, 20, 25, 30, 35, and 40°C and use small spindle (8 mm) with gap 2500 microns (2.5 mm), as well as strain sweep control, and test frequency 1.59Hz. The binders to be tested were PAV aged residue.

3. RESULTS AND DISCUSSION 3.1 Storage stability The softening point temperature (Tr&b) difference between top and bottom sections was used to evaluate OMB’s stability. A low Tr&b difference was observed in all of OMB as shown in Figure 2.

Different of Tr&b

0

0.2

0.4

0.6

0.8

1

1.2

2.5 5 7.5 10

OPFASH Cont ent (%) by weight of bit umen

Tr&b 1 day st orage Tr&b 3 days st orage

Figure 2: Tr&b differences changing by OPFASH

content for bitumen pen. Grade 80/100 The Tr&b should be controlled within 2°C at which OMB can be properly stored. There were no set standard tests in Malaysia, as an approach, temperature difference 2°C refers to the research conducted by researcher in Taiwan (J.C. Chen et.al., 2003) was used. All OMB have Tr&b different below 2°C as can be seen in Figure 2. OMB with 2.5% OPFASH has different Tr&b 0°C. For 1 day storage the other three OPFASH content have Tr&b different 0.5°C, and for 3 days storage OMB with 5% OPFASH has 0.5°C Tr&b different, while the other two OPFASH content 7.5 and 10% have 1°C different of Tr&b. These results showed that OPFASH compatible with bitumen when used as modifier. 3.2 Rheological testing As expected, adding the amount of OPFASH in the bitumen increasing the resistance to permanent deformation or rutting and resistance to fatigue cracking. The Strategic Highway Research Programme (SHRP) researchers considered rutting as a stress controlled (Freddy L. Robert et.al., 1996), cyclic

loading phenomenon in determining the rutting parameter chosen for specification purposes. With each of traffic loading cycle, work is being done to deform the HMA pavement surface. A part of this work is recovered by elastic rebound of the surface while some is dissipated in the form of permanent deformation or heat. In order to minimize permanent deformation (rutting), the amount of work dissipated during each loading cycle must be minimized. Mathematically, the work dissipated per loading cycle at a constant stress can be expressed as follows (Bahia, H.U. and D.A. Anderson (1995) :

⎥⎦⎤

⎢⎣⎡×=

δσπ

sin/*12

GW oc (1)

where, Wc = work dissipated per lod cycle, σo = stress applied during the load cycle, G* = complex modulus, Δ = phase angle. This equation indicates that the work dissipated per loading cycle is inversely proportional to G*/sinδ. For this purpose, the G*/sinδ parameter was chosen as a Superpave bitumen binder specification. Specification requirements for the DSR test parameters, when the unaged bitumen binder is tested, the G*/sinδ value must be minimum of 1 kPa, and when the RTFO residue is tested the G*/sinδ value must be a minimum of 2.2 kPa (Freddy L. Robert et.al., 1996). Fatigue cracking can occurs both in thick or thin of HMA pavement layers. In thick layers, fatigue cracking is typically considered a stress controlled, and in thin layers it is considered a strain controlled. Since fatigue cracking is known to be more prevalent in thin pavements, the SHRP researchers assumed that it should be considered mainly a strain controlled.60. Mathematically, the work dissipated per loading cycle at a constant strain can be expressed as follows (Bahia H.U. and D.A. Anderson (1996):

[ ]δπ sin*2 ×∈×= GW oc (2) where ∈ is the strain and the other variables are as previously described. This equation indicates that G* and/or δ are increased, more work will be dissipated per traffic loading cycle. The lower the amount of energy dissipated per cycle, the lower of fatigue cracking or any other damage to occur. The G*sinδ parameter was, therefore, chosen for Superpave specification purposes to limit the total amount of energy dissipated thereby minimizing fatigue cracking. The DSR specification requirement for G*sinδ parameter when PAV aged bitumen binder was tested must be maximum 5000 kPa (Freddy L. Robert et.al., 1996). Test results shown in Figure 3 for unaged sample and in Figure 4 for RTFO aged sample showed that for unaged sample, OMB can resist rutting until 65°C, and for RTFO

aged sample until 70°C reached by OMB with 5% OPFASH content.

Figure 3: |G*|/sinδ for unaged sample

|G*|/sin (delta) for RTFO aged sample

0

5

10

15

20

25

30

35

40

45

0 2.5 5 7.5 10

OP FAS H c ont e nt ( % by we i ght of bi t ume n) , 0 i s Ne a t B i t ume n

Temp. 50C Temp. 60C Temp. 65C

Temp. 70C Temp. 75C

Figure 4: |G*|/sinδ for RTFO aged sample

Figure 5: |G*|sin(delta) for PAV sample

The test results for PAV aged sample shows that OMB can resist fatigue cracking until 20°C reached by OMB with 2.5% OPFASH content, and the other resist at temperature 25°C. 4. CONCLUSION Storage stability test was known that there was no separation between OPFASH and bitumen or can be concluded that OPFASH was compatible to be used as bitumen modifier. This conclusion was also brought the meaning to the DSR test results. Since OPFASH-bitumen was compatible, without doubt, the DSR test results were also valid. The overall conclusion was Oil Palm Fruit Ash (OPFASH) feasible to be used as bitumen modifier. 5. ACKNOWLEDGMENT The writers wish to thank Prof. Dr. Ir. A.A.A. Molenaar and Prof. Ir. Martin van de Veen from the Road and Railway Section, Faculty of Civil and GeoScience Engineering of the Delft University of Technology, the Netherlands for permitting the writers to conduct DSR, BBR, and DTT tests for OPFASH-Modified Bitumen in the laboratory of Road and Railway Section, and for their guidance and supervision during the writers conducting the test. 6. REFERENCES Bahia, H.U. and D.A. Anderson. (1995). The SHRP

Binder Rheological Parameters: Why Are They Required and How Do They Compare to Conventional Properties. Transportation Research Board, Preprint Paper No. 950793, January 1995.

Department of Environmental, Ministry of Science,

Technology and the Environment Malaysia, (1999). Industrial Process and the Environment of Crude Oalm Oil Industry. Printed by: Aslita Sdn. Bhd. Kuala Lumpur, December 1999.

European Normalization EN 14770. Bitumen and

bituminous binders – Determination of complex modulus and phase angle – Dynamic Shear Rheometer (DSR)

Freddy L. Robert, Prithvi S. Kandhal, E. Ray Brown, Dah-

Yinn Lee, and Thomas W. Kennedy. (1996). Hot Mix Asphalt – Materials, Mixture Design and Construction. 2nd edition. NAPA Education Foundation, Lanham, Maryland. p. 84-85

Google Alert - Malaysia Palm Oil Industry 2009 Mohd. Warid Hj. Hussin, Prof. Ir. Dr. (2002). Blended

Cement Concrete – Potential without Misuse. Public Lecture, Universisti Teknologi Malaysia.

J.S. Chen, M.C. Liao, and C.H. Lin. (2003).

Determination of polymer content in modified bitumen. Journal of Materials and Structures. Vol. 36, November 2003, p. 594-598.

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PROPERTIES OF DUTCH TWINLAY POROUS ASPHALT UTILIZING LOCAL AGGREGATES Noor Halizah Abdullah School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia. nhalizah@yahoo.com Meor Othman Hamzah School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia. cemeor@eng.usm.my ABSTRACT: Porous asphalt was first attempted on Malaysian roads in 1991. It prevents hydroplaning, improve skid resistance and overall enhancement in traffic safety. However, the life span of Malaysian porous asphalt is much shorter compared to Dutch mixes. It is reported that the most durable and successful porous asphalt resides in the Netherlands. Therefore, it is justifiable to refer to the Dutch porous asphalt design as a guide to improve the performance of Malaysian porous asphalt mixtures. In 1990, the Dutch developed the double layer porous asphalt named as ‘Twinlay’. Twinlay is made up of a top finer thin porous mix which acts as a ‘sieve’ that prevents dirt from entering the bottom layer while the bottom layer consists of a much coarser but thicker porous base layer mix that can reduce the chances to trap dirt or pollutants. Twinlay offers possibilities for even more noise reduction and cleaning of Twinlay has proven manageable through experience in practice. Therefore, it is necessary to evaluate the performance of Dutch Twinlay porous asphalt mixes using local aggregates. Performance parameters measured includes permeability, Marshall stability and flow, indirect tensile strength (ITS) and abrasion loss. Local granite aggregates were batched and compacted by the Marshall Hammer. Conventional bitumen 60/70 penetration grade, modified binder PG76 and hydrated lime were used as binders and filler respectively. Mixes incorporating modified binder PG76 exhibits better performance for all conducted tests on specimens which includes permeability, abrasion loss, ITS, and Marshall stability test. Incorporation of modified binder increases the resistance to abrasion loss, and the tensile strength of the mixes. Key words: Porous asphalt; Double layer; Permeability; Abrasion loss 1. INTRODUCTION Porous asphalt (PA) is an advanced road surfacing technology which has been used in many countries. Its continuous air voids allows water to enter into the asphalt mix and flows through it. It is used worldwide for its favorable splash and spray properties and its reduction of aquaplaning under rainy conditions as well as its noise reduction property. Pores in the mix play the role of a drainage mechanism which absorbs considerable quantity of precipitation falling on them before becoming saturated. Compared to dense mix, PA is more susceptible to clogging and less durable. The pores in PA are easily clogged by dirt, silt, clay and debris especially in rainy conditions. When the pores are clogged, there will be a permeability loss and when the extent of clogging is severe, the benefits associated with open mix will vanish. In European countries, the PA surfacings offer a big potential to reduce traffic noise at source in harmony with a stricter environmental regulations related to traffic noise. Nonetheless, the noise absorbing capacity of PA is greater as the gradation becomes finer (Van Bochove, 1996). However, the finer graded PA is more prone to clogging. The Dutch experience with double layer PA was presented to the 1st Euroasphalt and Eurobitumen Congress held in Strasbourg (Van Bochove, 1996). Since the 1980’s, PA had been used as a wearing course for pavement in urban roads in the Netherlands with the first trial conducted in 1984. Years of experience and research by Heijmans Civil Engineering at Rosmalen

(The Netherlands) have led to a new development of PA. In 1990, the Dutch developed the double layer PA designated as ‘Twinlay’. Test sections were constructed since 1990 and these test sections took part on a large scale research project aimed at optimizing noise reduction of PA. Acoustic measurements showed that Twinlay offers possibilities for even more noise reduction, even at lower vehicle speeds. Cleaning of Twinlay has proven manageable through experience in practice (Van Bochove, 1996). The double layer PA consists of two different mix gradations. The top layer consists of a finer thin porous mix while the bottom layer consists of a much coarser but thicker porous base layer mix. The top layer acts as a ‘sieve’. Its finer layer prevents dirt from entering the bottom layer, while the bottom layer, which has larger pores, reduces chances to trap dirt or pollutants. Therefore, only the top layer gets clogged and the dirt is easily removed by existing field cleansing techniques which involves vacuuming of the dirt (Battiato et. al., 1996). The schematic diagram of the Twinlay PA is shown in Fig.1. The objective of this paper is to assess the properties of Twinlay PA using local aggregates and incorporating two types of bitumen, base bitumen 60/70 penetration grade and modified PG76 bitumen.

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Fig. 1. Schematic diagram of a Twinlay porous asphalt (Van Bochove, 1996) 2. METHODOLOGY

2.1. Materials Local crushed aggregates extracted from a local source and supplied by Quad Quarry Sdn. Bhd. were used in this study. Hydrated lime and OPC were used as fillers. Table 1 shows the basic properties of local crushed granite used in this paper. Bitumen penetration grade 60/70 and modified bitumen PG76 supplied by Shell Malaysia were incorporated in the mix. The properties of bitumen used are presented in Table 2. The aggregates were washed, dried, and sieved into the selected size range according to Dutch aggregate gradation and sieve sizes. There were two gradations used, the top and bottom layer which differs in terms of their nominal maximum aggregate sizes of 8 mm and 16 mm respectively. Fig.2 illustrates the gradation for top and bottom layers used in this study.

Table 1. Properties of local crushed granite used in this study

Properties Specification Requirement (JKR, 2008)

Result Conform

Abrasion Loss Less than 25% 23.6% Yes Aggregate Crushing Value Less than 25% 17.3% Yes

Flakiness Index Less than 25% 18.1% Yes Water Absorption Less than 2% 0.7% Yes

Polished Stone Value Not less than 50 51.8 Yes

Table 2. Properties of bitumen used in this study

Basic Properties Bitumen

60/70 PG-76 Specific Gravity (g/cm3) 1.030 1.024 Penetration at 25 °C (x0.1mm) 63 45 Softening Point (°C) 49 64 Ductility at 25 °C (cm) > 100 88.8

Fig. 2. Dutch Twinlay PA gradation 2.2. Specimen Preparation Specimens were prepared in a Marshall standard mould with a total height 70 mm with top layer thickness of 25 mm. Mix for top and bottom layers were prepared separately according to their respective binder contents as shown in Table 3. The bottom layer aggregates and bitumen were blended at the mixing temperature based on viscosity results. The mix was then conditioned at the compaction temperature for 2 hours. The top layer aggregates were then mixed with bitumen and also conditioned for two hours prior to compaction. The mass of top and bottom layer mixes were calculated based on their corresponding single layer densities. The actual amount of mixes required was calculated based on the density and volume obtained from its single layer properties. The bottom layer was weighed first and poured to the bottom of the mould and the top layer was then weighed and placed on top of the bottom layer. A total of 50 blows were applied on each face of the specimen. The mixing and compaction temperatures are shown in Table 4.

Table 3. Binder contents for top and bottom layers

Type of Layer Binder Contents (%)

Top 6.0 Bottom 4.2

Table 4: Mixing and Compacting Temperatures

Type of Binder Temperature (oC)

Mixing Compaction 60/70 165 155 PG-76 180 170

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2.3 Specimen Testing 2.3.1 Permeability Test Permeability is an important property of an open mix. The hydraulic conductivity of the compacted specimens was expressed in terms of the coefficient of permeability (k), determined using a falling head water permeameter. This test involved a specimen secured to the permeameter base plate and pouring water into the perspex tube while sealing the orifice with the rubber stopper. The rubber stopper was then removed and the time taken for water to fall through two designated points on the permeameter standpipe was recorded. The coefficient of permeability was calculated based on the formula shown in Eq.(1).

⎟⎠⎞

⎜⎝⎛=

21log3.2 10 h

hAtaLk (1)

where k is the coefficient of permeability (cm/s), A is the cross section area specimens (cm2), a is the cross section area standpipe (cm2), L is the height of specimens, t is time taken for water in standpipe to fall from h1 to h2 (s), and h1, h2 is the water level at t1 and t2 (cm) 2.3.2 Cantabro Test

The Cantabro test was conducted to determine specimen resistance to particle loss. The test was conducted in the Los Angeles (LA) machine, without steel balls. Twinlay specimen was conditioned at 25°C for at least four hours before placing it in the LA machine to tumble for 300-drum rotations. The percentage mass loss after 300 rotations compared to the original mass defined the abrasion loss as shown in Eq.(2).

1001

21% ×−

=M

MMLoss (2)

where M1 is the initial mass (g), and M2 is the final mass (g). 2.3.3 Indirect Tensile Strength The indirect tensile strength (ITS) was used to determine the strength required to split the specimen into two halves. This serves as the tensile strength of the specimen. The test was done according to ASTM D4123, (ASTM, 2005). The specimen was cured at 20oC for at least 4 hours before conducting the test. Compression loads were applied parallel to the vertical diameter plane by using the Marshall testing machine. The specimen usually fails along the loaded plane when tensile stress loading acts perpendicular to the applied load plane (Kok and Yilmaz, 2009). The ITS value is calculated using Eq.(3).

hdFITS

π2000

= (3)

where F is the maximum applied load (N), h is the specimen thickness (mm), and d is the specimen diameter (mm). 2.3.4 Marshall Stability Test The Marshall test was carried out to determine the stability and flow of the specimen when placed between two split breaking heads in an unconfined manner. Load at a constant rate of 50.8 mm/min was applied perpendicular to the longitudinal axis of the specimen until failure. Stability is expressed in kN and is equivalent to the maximum load applied and flow is the deformation that took place up to the point where failure occurred and measured in units of mm. 3.0 RESULT AND DISCUSSION 3.1 Coefficient of Permeability This test was conducted using the falling head permeability apparatus. Atleast three different specimens were tested for permeability and the average permeability of both mixes are recorded. The permeability of Dutch twinlay PA is presented in Fig.3. It was found that mixes with PG76 grade bitumen exhibits higher coefficient of permeability compared to bitumen penetration grade 60/70. Incorporating a polymer modified binder in the mix has increased the permeability of the mix. Faghri et. al. (2002) had also reported that with the use of polymer modified bitumen had increased the permeability of open-graded asphalt mixes.

Fig. 3. Permeability test results 3.2 Abrasion Loss The abrasion loss was conducted on specimens conditioned at 25°C. A total of three specimens for each type of mix was tested. The average values from the three samples were taken as the abrasion loss. The test result is shown in Fig.4. It can be seen that the mix made with bitumen grade 60/70 produces higher abrasion loss compared to PG76. Mixes made with modified bitumen PG76 has stronger bond and more resistant to particle

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loss. Nielsen et. al. (2004) reported that the use of modified binder had improved the resistance of PA to particle loss.

Fig. 4. Abrasion loss results 3.3 Indirect Tensile Strength The results for the ITS values for two different types of bitumen is shown in Fig.5. From the results, it can be seen that the mixes made with modified bitumen PG76 exhibit higher ITS values compared to conventional 60/70 penetration binder. The use of modified bitumen increases the mean ITS values by 13.5%. A study done by Faghri et. al. (2002) also found that the use of polymer modified bitumen has increased the tensile strength of open-graded mixes.

Fig. 5. Indirect tensile strength results

3.4 Marshall Stability Test RESULT The ratio of stability (kN) to flow (mm) is used to define the Marshall Quotient (MQ). MQ is a measure of the materials resistance to shear stresses, permanent deformation and hence rutting (Zoorob and Suparma, 2000). High MQ values result a high stiffness mix with a greater ability to spread the applied load and resistance to creep deformation (Kok and Yilmaz, 2009). The Marshall test results are presented in Table 5, while Fig.6 illustrates the ratio of stability to flow. It can be seen that the

twinlay porous asphalt made with bitumen grade PG76 exhibit 37.5% higher stability compared to mixes made with conventional bitumen.

Table 5. Marshall test results

Binder Type

Stability, Ms (kN)

Flow, F (mm)

MQ (Ms/F) kN/mm

60/70 5.32 2.77 1.92 PG76 10.38 3.38 3.07

Fig. 6. Marshall quotient 4.0 CONCLUSION This paper presents the results of the Dutch Twinlay PA mixes properties using local aggregates and two different types of binder. Generally, mixes incorporating modified binder PG76 exhibits better performance for all conducted tests on specimens which includes permeability, abrasion loss, ITS, and Marshall stability test. Incorporation of modified binder increases the resistance to abrasion loss, and the tensile strength of the mixes. ACKNOWLEDGEMENTS The authors would like to acknowledge the Malaysian Ministry of Science, Technology and Innovation that has funded this research grant through eScience Fund program that enables this paper to be written. Many thanks are also due to technicians of the Highway Engineering Laboratory at the Universiti Sains Malaysia for their help. Acknowledgments are also due to the suppliers of bitumen and aggregate, which include Shell Ltd., Singapore and Kuad Quarry Sdn. Bhd., Penang respectively. REFERENCES ASTM, 2005. ASTM D4123: Standard test method for

Indirect Tension Test for Resilient Modulus of bituminous paving mixtures, Annual Books of ASTM Standard, Vol. 04.03, West Conshohocken, PA

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Battatio G., Donada M., Grandesso P., Russiani M.

(1996). DDL a New Generation of Sound Absorption Draining Layers. 1st Euroasphalt & Eurobitume Congress 1996.

Bochove Van G.G. (1996). Twinlay, a New Concept for

Porous Asphalt. 1st Euroasphalt & Eurobitume Congress 1996.

Faghri, et. al., 2002. Performance Improvement of Open-

Graded Asphalt Mixes, URITC Project No. 536144, Transportation Centre, University of Rhode Island.

JKR, 2008. Standard Specification for Road Works

(Section 4: Flexible Pavement), Public Works Department, Ministry of Works Malaysia, Kuala Lumpur.

Kok, B. V. and Yilmaz, M., 2009. The Effects of Using

Lime and Styrene-Butadiene-Styrene on Moisture Sensitivity Resistance of Hot Mix Asphalt, Construction and Building Materials 23, 1999-2006.

Nielsen C.B., Nielsen E., Andersen J.B., and Raaberg J.,

2004. Development of Durable Porous Apshalt Mixes from Laboratory Experiments, 3rd Eutoasphalt & Eurobitume Congress, Vienna, [090].

Zoorob, S. E., Suparma, L. B. (2000), Laboratory Design

and Investigation of the Properties of Continuously Graded Asphaltic Concrete Containing Recycled Plastic Aggregate Replacement (Plastiphalt), Cement Concrete Composites 2000:22:233-42.

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1. INTRODUCTION

A “heat island” is perhaps a “reversed oasis” and occurs when the thermal energy stored at a particular location causes higher temperatures there than that in the surrounding area. Such locations are normally found in urban and sub-urban areas. During hot weather and particularly at night, the ambient temperatures are warmer in cities than in the surrounding areas. An Urban Heat Island (UHI) is a consequence of the intrusion into the natural green space by heat absorbing infrastructure such as high rise buildings, road pavements, parking facilities etc. This is further exacerbated with the lack of planned compensating landscapes (see figure 1). With rapid urbanization and increasing growth of cities, UHI related problems of thermal discomfort lead to derogatory human health and mortality which are coupled with environmental issues of increased energy consumption, reduced air quality and accelerate significantly the green house effect.

Fig. 1. Typical temperature profile across an UHI

(Source: www.urbanheatislands.com)

UHIs are becoming equally important as climate change where the urban fabrics are susceptible to heat absorption. Heat islands define local-scale temperature difference between urban and rural areas, whereas global warming refers to the gradual rise of the worldwide average surface

FIELD STUDY OF URBAN HEAT ISLAND EFFECTS FROM ASPHALT PAVEMENTS

Chitral Wijeyesekera Professor in Civil Engineering, School of Computing, IT & Engineering, University of East London, UK

& UTHM Johore Malaysia chiral@uel.ac.uk

John Walsh Senior Lecturer in Civil Engineering, School of Computing, IT & Engineering, University of East London, UK

j.w.walsh@uel.ac.uk

Robert Allen Aggregate Industries (UK) Ltd.,, UK Bob.Allen@aggregate.com

Helen Bailey Aggregate Industries (UK) Ltd.,, UK

ABSTRACT: The rapid growth of worldwide urbanization arouses concerns on Urban Heat Island (UHI) effects particularly within areas where the population density is high. Road pavements are necessary facets of urbanization and have important localized environmental effects; absorbing heat during the day and radiating it back out at night time contributing to significant localized temperature increase. Furthermore social and ecological effects are felt in terms of heat related illness and breakdown of sensitive environmental systems leading to derogatory contribution to global warming. Due to the large area covered by pavements in urban areas, they are an important element to consider in the heat island migration. The temperatures of the pavements depend on the percentage composition of the solar energy, and the pavement material’s thermo physical properties such as solar reflectance (albedo), thermal conductivity, and thermal emittance. Installation of green roofs, cool pavements and increasing tree and vegetation cover are some of the strategies being adopted to reduce the urban heat effects. Preliminary field monitoring of the urban heat island levels within an array of different pavement materials are being conducted on 5 test pavement bays constructed at an Aggregate Industries (UK) site. The temperature distribution within the test bays were data logged continuously for the field analysis. The heat flow characteristics through the pavement constituents, including thermal energy input and output are evaluated and assessed. Innovative systems to reduce such temperature variations in order to extend life of the asphalt pavements as well as the possibility of harnessing the UHI as an energy source are explored. .

Keywords: Urban heat island, heat transfer, road pavement, thermo-physical properties

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temperatures. The overall UHI patterns are essentially similar for most cities apart from the minor differences due to climate and geography. As shown in figures 1 and 2, the temperature pattern is highest in the highly built up down town area and diminishes towards the edge of the urban areas and into the countryside.

Fig. 2. Surface temperature of London at 2130 hrs on 7 August

showing the signature of urban heat island. Source: NASA

1.1 Aim and objectives of the research The aim of this study is to investigate the effect of asphalt pavement on urban heat island and to assess the impact of the fabric of the road pavement on UHI.

A critical literature review of UHI is objectively followed with a description of the field set up used to make observations of the thermal flux through a pavement. Elements of heat transfer studies are provided as a basis for UHI reduction strategies.

2. URBAN HEAT ISLAND

Figure 2 is an image of the Land Surface Temperature (LST) distribution over the London area as observed on 7th August 2009. Fractional vegetation cover modulates the proportions of vegetation and ground visible to a sensor. The temperature differences (generated by the radiated thermal energy) between the vegetation canopy and the ground affect the measurement of LST. In non vegetated areas, LST measurements typically represent the radiometric temperature levels of bare soil. With increasing amounts of vegetation cover, the temperature levels recorded by a LST sensor reflect more closely the temperatures of green leaves, and the canopy temperature. Therefore such LST observations need to be carefully scrutinized to separate the contributions from each part of the hybrid shaded and sunny vegetation-ground system. LST measurements are also influenced by the viewing angle, the lower atmosphere and the differential temperature between the vegetation canopy, its variable biophysical properties and the soil background.

For any surface material, certain thermal properties, such as heat capacity, thermal conductivity and thermal inertia, significantly govern the transient temperature of a body with its surroundings. These thermal properties vary with soil type and its moisture content. Dry, bare, and low-density soils have a relatively low thermal inertia. The thermal emissivity (via the combined thermal processes of conduction, convection and radiation) of soils is also dependent on soil moisture conditions and the density. Though the temperature differences between the urban and countryside is obviously evident at midday, the UHI effect causes the greatest temperature difference to occur two to three hours after sunset. The latter effect results from the gradual release of the heat stored during the day by the asphalt and concrete structures. Most building materials are impermeable and watertight, which does not therefore facilitate the ready dissipation of the sun’s heat. Dark Construction materials in concert with canyon like configurations of buildings and pavements collect and trap more of the sun’s energy. Temperatures of dry dark surfaces exposed to direct sun light can reach up to 88ºC during the day, whereas the vegetated surfaces with moist soil under similar conditions might reach only 18ºC. Anthropogenic heat or human produced heat, slower wind speeds and air pollution in urban areas also contribute to heat island formation (Gartland, 2008).

Permeability and volumetric heat capacity of pavement layers greatly influence its heat exchange. Impermeable pavements reduce evaporation and the high volumetric heat capacity causes negligible flow of water or cooling air through them. These generate high night time air temperatures described as a nocturnal urban heat island (Asaeda and Thanh, 2000) Average summer temperatures are predicted to increase by 2.5o to 3o C by the 2050s together with a high CO2 emissions scenario leading to an increase of 5-10 days per year of exceptionally hot days (>30oC). This hotter air contributes to the acceleration of smog (ozone) production, which is a major health and environmental concern (Gray and Finster, 2000).

3. HEAT TRANSFER IN PAVEMENTS

The wavelengths of solar radiation are less than 3mm. These heat the surfaces on which they fall. Such surfaces being much cooler than the surface of the sun, the radiation emitted by the urban fabric have a much longer wavelength. Figure 3 illustrates the thermal process prevalent in a pavement. These are important aspects to consider in heat islands mitigation. The complex heat transfer mechanism involves different processes of thermodynamics. In addition to the processes, there are thermophysical properties, such as solar radiation, solar reflectance (albedo) material heat capacities, surface roughness; heat transfer rates, thermal emittance and permeability that contribute to UHI.

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Fig. 3. Heat transfer processes from and within a pavement 3.1 UHI Sensitive Thermophysical Properties of pavement 3.1.1 Solar Reflectance or Albedo Solar reflectance, or albedo, is the percentage of solar energy reflected by a surface. It is a primary determinant of a material’s maximum surface temperature. Conventional paving materials such as asphalt and concrete have solar reflectance of 5 to 40 percent, which means that they absorb 95 to 60 percent of the energy reaching them instead of reflecting it into the atmosphere (Golden and Kaloush 2005). These values change with time depending on age and the type of material. 3.1.2 Permeability Permeability of the pavement provides greater flow capacity of air, water, and water vapour into and through the voids of the pavement. Moisture within the pavement structure evaporates as the surface heats, thus drawing heat out of the pavement, similar to evaporative cooling from vegetated land cover. Permeable surfaces are currently used to control storm water runoff; the evaporative cooling effect also could be used for UHI reduction. 3.1.3 Thermal Emittance A material’s thermal emittance determines how much heat is radiated per unit area at a given temperature, that is, how readily a surface sheds heat. When exposed to sun light, a surface with high emittance will reach thermal equilibrium at a lower temperature than a surface with low emittance, because the high  emittance surface gives off its heat more readily 3.1.4 Thermal Conductivity (k) Pavements with low thermal conductivity may heat up at the surface but will not transfer that heat into the other

pavement layers as quickly as a pavement with higher conductivity. It can be extended further that lower thermal conductivity of the pavement causes high daytime temperature as it stores more energy, than transfer it.. 3.1.5 Heat Capacity (Thermal Mass) Urban materials can store more heat than natural materials, such as dry soil and sand. The higher heat capacity of conventional urban materials contributes to heat islands at night, when materials in urban areas release the stored heat. 3.1.6 Thickness The thickness of pavement also plays a significant role in contributing to UHI because it displays the amount of energy it will store. The thicker pavements will store more heat than thinner pavements. 3.2 Field Test Site & UHI Monitoring

Fig. 4 Instrumented Road Pavement Test Site – Aggregate Industries UK

A dedicated road pavement testing site with 5 different pavement bays (see figure 4), constructed at the Aggregate Industries Research Centre based in Hulland Ward, UK has been adapted further to accommodate the UHI monitoring. Figures 5 and 6 presents details of two of the five different pavement bays made of dissimilar traditional and innovative sustainable materials to evaluate the influence of traditional and non-porous materials. Also included for the identification of effectiveness and influence are sustainable pavement materials such as Charcon Permavoid, Hydrain granular gravel reservoir bed, reinforced and unreinforced geotextiles. These are used in the test bays as probable thermal barriers and porous layers. Charcon Permavoid (figure 5) is aplastic open geocellular load bearing structure while Hydrain (figure 6) is a porous concrete. The asphalt surface and asphalt base shown in figure 5 is dense impermeable asphalt.

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Temperature sensors in the form of thermocouples are located at the boundaries of the various pavement fabrics. Thermocouples have been read hourly and data logged since August 2008. Some of these observations are discussed briefly in this paper.

Fig. 5 Cross section details of the pavement in Bay X.

Fig. 6 Cross section details of the pavement in Bay Y.

Figure 7 shows the temperature observations logged over a typical day. Note the temperatures within the pavement layers remain consistently higher than that of the air temperature which is traditionally measured at a height of 2m above ground surface. There is a distinct time lag between the pavement and the air temperatures with the effect decreasing with depth.

A peak temperature of 35.4ºC was observed on the asphalt surface in Bay X (see figure 8) compared to a 30.8ºC seen on Bay Y (figure 9) confirming that the dense impermeable asphalt (Bay X) is more susceptible to solar radiation and more rapidly conducts and stores the heat than the porous asphalt (Bay Y). Note that the comparisons of figures 8 and 9 are for the same day (see the same air temperature variation and that of the sand and gravel layer). Furthermore there is very little change in temperature beneath the first geotextile layer.

Fig. 7 Temperature variations observed from a bay on a typical

day (3rd September 2008)

Fig. 8 Temperature variations on 14/8/2008 - Bay X

Fig. 9 Temperature variations on 14 Aug 2008 – Bay Y

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Fig. 10 Temperature isochrones in Bay X

Fig. 11 Equations to temperature curve fits (Bay X)

Fig. 12 Equations to temperature curve fits (Bay Y)

The temperature isochrones shown in figure 10 indicate that there are significant temperature variations to depths in excess of 600 mm within the pavement.

Figures 11 and 12 show the polynomial fits to the temperatures measured using thermocouples (A,B and G,H) placed at the boundaries of the “asphalt” layer in bays X and Y respectively. Thermal conductivities calculated from

the traditional asphalt and the porous asphalt are 1.42 W/mºC and 2.30 W/mºC respectively. While factors such as prevailing weather patterns, climate, geography and topography are beyond a designer’s control, there are tangible heat island reduction strategies in vegetation, landscaping, and improved building and road pavement materials leading to the tangible construction of reflective and cool roofs and pavements.

4. CONCLUSIONS

Temperature monitoring within the test pavements has given a wealth of information for strategic analysis. There is observed evidence that the porous pavements have low thermal storage with indications of up to 60% reductions in thermal gradients.

The use of sustainable and innovative materials presented (Charcon Permavoid and Hydrain) creates a platform for protecting the environment from adverse UHI effects. In colder cities at higher elevations, the heat islands are seen as beneficial because of its winter warming effects. In most cities throughout the world, the effects of summer heat island are seen as a major problem.

ACKNOWLEDGEMENT

Access to field information from Aggregate Industries (UK) is gratefully acknowledged.

REFERENCES

Asaeda, T., and Thanh, V. (2000), .Characteristics of permeable pavement during hot summer weather and impact on the thermal environment Building and Environment, 35:. 363-375. Gartland L (2008), Heat Islands – Understanding and mitigating Heat in Urban areas, London. Earth-scan publication. Golden, J., Kaloush, K. (2005), ‘Mesoscale and Microscale evaluation of surface pavement impacts on the urban heat island effects’, The International Journal of Pavement Engineering, 7 (1):37‐52.. Gray, K., and Finster, M. (2000), .The Urban Heat Island, Photochemical smog, and Chicago: Local features of the problem and solution,. Department of Civil Engineering, Northwestern University, Evanston, IL USA. Wong, N.C., and Chen, Y. (2009), Tropical Urban Heat Islands- Climate, Buildings and greenery, Milton Park, London, Taylor and Francis Publication.

PCI DETERMINATION USING EXPERT SYSTEM

Norlela Ismail1, Amiruddin Ismail2, Riza Atiq Abdullah O.K.Rahmat3

Sustainable Urban Transport Research Centre / Dept. of Civil and Structural Engineering Faculty of Engineering and Built Environment Universiti Kebangsaan Malaysia, Selangor, Malaysia E-mail: 1norlelaismail@uniten.edu.my; 2abim@vlsi.eng.ukm.my; 3riza@vlsi.eng.ukm.my

ABSTRACT: Airport networks are one of the important assets in a country especially after the air travel has become increasingly popular as a mode of transportation. Large investments in time and money are required by aviation agencies to sustain and maintain the airport networks operation in a safe and smooth condition. Aviation agencies responsible for operation and maintenance of airport continually face problems with pavement distress and deterioration which occur due to environmental factors and increasing weight and volumes of traffic. The pavement performance evaluation procedure based on Pavement Condition Index (PCI) was developed in the late 1970s by the U.S. Army Corps of Engineers to help manage airport pavement. The use of the PCI has received wide acceptance and formally adopted as standard procedure worldwide. This standard employs the visual distress in which distress type, severity, and quantity are identified and rating system that rates the pavement condition from 0 for a failed pavement to 100 for a perfect pavement. PCI is also used to measure the structural integrity and surface operational condition of a pavement. Computing the PCI manually is not a tedious operation but the calculations involved are time consuming. This paper presents the determination of PCI using expert system. The method is based on procedures in ASTM D5340 (Standard design method for airport pavement condition index surveys). The expert system will automatically calculate the PCI of each sample unit survey once the user enter the distress information. The system also determine the percentage of deduct values based on distress mechanism and the primary cause of pavement deterioration. Using several sample unit of pavement, this system is then tested by comparing the output results with manual calculation and MicroPAVER. The results indicate that the PCI calculated from the expert system is almost similar with the other two.  Key words: Pavement Management System; Pavement Condition Index; Expert System

INTRODUCTION Upon completion, likes highway pavements, airport pavements begin to experience constantly deterioration due to larger weight and volumes of aircraft traffics and climatic factors. This deterioration, if being unattended, can eventually pose safety risks to airplanes taking off or landing which may increase the possibility of aircraft accident and aircraft operation delayed. Failure to perform suitable treatment in the early stage of deterioration may also results in serious pavement distress that may require costly repairs in term of money and closure time (FAA 2003). It is important to carry out the right maintenance at the right time in order to ensure the smooth airport operations and enhances the longevity of the pavement. However, managing of an aging pavement infrastructure is a difficult task especially with the growing budgetary constraints. Due to that, many

agencies have recognized the need for pavement management (Haas 1997) to link together the activities of planning, designing, constructing, maintaining and rehabilitating pavement. Pavement management systems (PMS) are then being developed to provide a structured and comprehensive approach to pavement management. PMS in airport pavement has grown dramatically since 1985. Their primary function is to assist engineers and decision makers in selecting the most cost effective way of strategies for providing and maintaining pavements in an adequate and safe condition over a given period of time. Ritchie et al. (1987) claimed that pavement surface condition play a pivotal role in the analysis and design of pavement rehabilitation strategies. As distresses visible on the pavement surface provide valuable input in the rehabilitation design process, most of the airport agencies conduct surveys on pavement condition as additional information to

support their decision in maintenance and rehabilitation of a runway. In order to standardize the survey methods and pavement ratings, pavement condition index (PCI) was developed. The PCI developed by the US Army Corps of Engineers in mid 1970’s seems the most common airport pavement distress survey used by airport agencies to help manage airport pavement (Shahin et al 1980; Shahin 1982, 1994; Michael et al. 1998). It has gained widespread acceptance and has been formally adopted as standard procedure worldwide. Shahin et al. (1980) also stated that PCI is the first tool used in the pavement rehabilitation process because it provides a standard measure of the pavement condition in term of structural integrity and operational condition, an objective and rational method for identifying maintenance and repair needs, and an early warning system for identifying expensive repair project. Computing the PCI manually for a single sample unit is not a tedious operation but it is time consuming especially when involving large volume of data (Shahin 1994). This paper presents the determination of PCI using an object oriented expert system based on KAPPA-PC to speed up the distress evaluation process. It is part of the modules in the early stage of the prototyping Expert System for Airport Pavement maintenance and Rehabilitation (ES-APAM) development. MATERIALS AND METHODS The development of the prototyping expert system for Airport Pavement Maintenance and Rehabilitation (ES-APAM) is generally to give advice on making decision in selecting the appropriate maintenance and rehabilitation strategies for flexible airport pavement. It is developed using KAPPA-PC expert system shell, where the rule-base reasoning and other decision process operate on objects and still in the early stage. This system consists of several modules that include the distress evaluation module. In the ES-APAM distress evaluation module, the decision made in implementing the PCI inspection is based on procedures in ASTM D5340 (Standard design method for airport pavement condition index surveys). The PCI is a numerical index, which rates pavements on a scale of 0 for a failed pavement to 100 for a pavement in perfect condition. It is determined based on the results of a visual condition survey in which the type, severity, and quantity of distress are identified. For airport pavement asphalt surfaces, ES-APAM considered all sixteen types of distresses as in Figure 1. Weighted deduct value is

used to combine data on each distress type, severity level, and distress density into a single condition value. For section samples that have distresses with deduct value greater than five points, modified deduct value is used, which is shown in Figure 2. This value is subtracted from 100 to give the PCI value. ES-APAM also used the survey data to compute the structural condition index (SCI) and a FOD condition index (FCI). The procedure used for computing the FCI value is similar to the PCI, but only for several distresses which is shown in bold in Figure 1. These indices are tools that could help users to quickly reduce the number of feasible rehabilitation option.

Distress Severity Alligator Cracking Bleeding

L, M, H n/a

Block Cracking Corrugation Depression

L, M, H L, M, H L, M, H

Jet Blast Erosion n/a Joint Reflection Cracking L, M, H Long and Trans Cracking L, M, H Oil Spillage n/a Patching Polished Aggregate

L, M, HL, M, H

Raveling and Weathering Rutting

L, M, H L, M, H

Shoving L, M, HSlippage Cracking Swelling

n/a L, M, H

L=Low, M=Medium, H=High Figure 1: Distress List for Airfield Asphalt Surface (Shahin 1994)

Figure 2: Corrected deduct value for Airfield asphalt pavement (Shahin 1994)

RESULTS AND DISCUSSION

The result of this study is the output of the prototyping Expert System for Airport Pavement maintenance and Rehabilitation (ES-APAM) in surface evaluation which are presented via figures and illustration. Figure 3 shows the window of distresses considered for asphalt surfaces of airfield in the ES-APAM. By clicking on the help command in the interface window located in Figure 3, the module helps the user identify the type of distress and

select the correct severity level by describing each distress by severity as in Figure 4. The user has to insert the distress of quantity data for each severity level of particular distress type and confirm the data, which as shown in Figure 5 and Figure 6 respectively. For making the system calculate the PCI, determine the percentage of deduct values based on distress mechanism (i.e. load, climate, and other) and give the primary cause of pavement deterioration, the user need to press the forward button in Figure 3.

Figure 3: Selection of distress type

Figure 4: Description and severity level of distress

Figure 5: Distress quantity input data

In order to verify the result of the ES-APAM system, few sample of airport pavement with several distress type and their severity levels was chosen in this study. Table 1 shows the data of seven samples taken from one section of Sandakan Airport in Malaysia. The PCI result of the expert system is then compared to manual calculation and MicroPAVER software, where MicroPaver is the most widely software used for pavement management in airport agency. From Table 2, the results show that the PCI calculated from the expert system is almost similar with the MicroPAVER. The comparative result is illustrated clearly on graph in Figure 7.

Figure 6: Confirmation of distress quantity data

Table 1: Input data of local sample

Sample 1 2 3 4 5 6 7

Facility Type Pavement Type Sample Area Distress Type Alligator Crack (L) Long/Transverse Crack (L) Long/Transverse Crack (M) Patching (L) Rutting (L) Bleeding

Runway AC

450 m2 -

29.83 m - -

13.33m2 -

Runway AC

450 m2 -

6.96 m -

2.03 m2 - -

Runway AC

450 m2

3.12 m 356.8 m

30 m 0.25 m2 0.70 m2

-

Runway AC

450 m2 -

33.59 m -

2.25 m2 -

1.30 m2

Runway AC

450 m2 -

21.31 m 7.5 m

0.25 m - -

Runway AC

450 m2 -

21.3 m -

0.25 m - -

Runway AC

450 m2

2.20 m2 68.7 m

- 0.25 m

- -

Table 2: PCI determination by manual, MicroPAVER and ES-APAM

Sample PCI

1 2 3 4 5 6 7 mean Manual Micro PAVER ES-APAM

74.5 74

74.54

93.5 94

93.7

48 48

47.64

76 77

76.16

62 62

61.57

92 92

91.64

78 79

78.22

74.85 75

74.78

Figure 7: Graph of manual, MicroPAVER and ES-APAM Pavement Condition Index

CONCLUSION

Distresses visible on the pavement surface provide valuable information in the maintenance and rehabilitation design process. To support their decision in maintenance and rehabilitation of a runway, many airport agencies conduct surveys on pavement condition that produce a pavement condition index. The PCI developed by the US Army Corps of Engineers has received wide acceptance and formally adopted as standard procedure worldwide. The method of determining the numerical value of PCI is simple operation but the calculations involved are time consuming. This paper presents the determination of PCI, which is in a part of the distress evaluation module in the prototyping Expert System for Airport Pavement maintenance and Rehabilitation (ES-APAM). The method in calculating the PCI is based on procedures in ASTM D5340. Seven sample of airfield pavement in Sandakan Airport, Malaysia is evaluated using ES-APAM. The results of PCI when compared to the manual calculation and MicroPAVER show similarity. This shows that the expert system has revealed satisfactorily findings in a faster PCI determination. ACKNOWLEDGEMENT We would like to thank the Malaysia Airport Holding Berhad (MAHB) for providing information and data.

REFERENCES FAA, Advisory Circular (2003). Guidelines and

Procedures for Maintenance of Airport Pavements, AC 150/5380-6A,FAA Washington, D.C.

Shahin,M.Y., Darter, M.I and Kohn S.D. (1980).

“Condition Evaluation of Jointed Concrete Airfield Pavements”, Transportation Engineering Journal

Shahin, M.Y. (1994). “Pavement Management For

Airport, Roads, and Parking Lots”. Chapman & Hall, New York. ISBN 0-412-99201-9.

Michael G., and Patrick, S. (1998). “Airport

pavement management systems: an appraisal of existing methodologies”. Transportation Research Part A: Policy and Practice. Volume 32 (3), pp 197-214. DOI 10.1016/S0965-8564(97)00008-6.

Shahin, M.Y. (1982). “Airfield Pavement Distress

measurements and Use in Pavement Management”. Transportation Research Record, 893, pp 59-63.

Ritchie, S.G. (1987). “Expert System in Pavement

Management”. Journal of Transportation Research. 21A (2) pp 145-152. DOI 10.1016/0191-2607(87)90007-0

Haas R (1997). “Pavement Design and Management

Guide”. Transportation Associate of Canada. ISBN 1-55187-114-9.

AN ASSESSMENT OF THE SURFACE ROUGHNESS INDEX OF VARIOUS BITUMINOUS PAVEMENTS IN MALAYSIA.

SULEIMAN ARAFAT YERO arafatyero@yahoo.com Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 skudai, Johor, Malaysia. Assoc.Prof.Dr. Mohd. Rosli bn Hainin roslihainin@utm.my Assoc.Prof.Dr. Abdulaziz bn Chik Azizchik@utm.my Dr. Haryati Yacoob Yacoob.h@gmail.com Abstract: The road system of Transportation is the major means of transporting goods and services in a developing country like Malaysia, hence the need for the assessment on the performance of the pavements becomes of paramount importance. The roughness of the road surface constitutes the frictional properties of the pavement surface and in turn related to the safety , smoothness and the ease of the driving Path. The roughness of a pavement is an important parameter in determining the comfort level of the riding path on a pavement, and this roughness of the pavement surface is related to the vehicle vibration, operating speed, wear and tear of the wheels. The surface roughness of a pavement is determined using the International roughness index (IRI), which is a measure of the texture of a pavement surface. This study investigated mainly three classes of bituminous pavement surfaces in Malaysia using the Australia road research board (ARRB) walking profilometer. The surfaces include asphalt concrete wearing (ACW), stone mastic asphalt (SMA), and surface dressed (SD) surfaces on jalan tebrau, jalan UTM-utama, jalan potian in Johor and jalan parit yaani in Batu Pahad. The study was conducted on the six selected roads and 60 test points where investigated. The results obtained from the study indicated that the surface dressed surfaces have the highest value of IRI, then the SMA surfaces and the least was the ACW surfaces indicating a smoother surface. Keywords: Walking profilometer, ACW, SMA, SD, and IRI INTRODUCTION Among the various means of transportation which include sea, air, rail, the road transportation system becomes the leading means of transportation in Malaysia. There has been considerable publicity on the comfort and safety of these roads. Roughness of a road (or runway) is an important parameter which not only indicates the comfort level of ride over a pavement surface, but it is also related to vehicles vibration while in motion, the vehicle operating speed, wear and tear of the wheels

with time, and the resulting operation cost of the vehicle. A pavement, which is structurally sound to sustain heavy load repetitions, may even be unserviceable functionally if its surface is rough and distressed. Roughness index is typically considered to be the high frequency, short wavelength component of a measured surface. Roughness plays an important role in determining how a real object will interact with its environment. Rough surfaces usually wear more quickly and have higher friction coefficients than smooth surfaces.The roughness index is a function of the smoothness of the pavement, comfort and its safety to the road user. The surface roughness is quantified by the vertical deviations of a real surface from its ideal form. If these deviations are large, the surface is considered to be rough; if they are small the surface is smooth. Roughness is often a good predictor of the performance of a mechanical component, since irregularities in the surface may form nucleation sites for cracks or corrosion that will eventually lead to the failure of the pavement [8]. It is also paramount to note that examining the performance of the wearing course of a pavement and the quantification of the roughness level of the pavement surface evolves as a prime concern to the highway engineer. A road profile is a two-dimensional part of the road surface, taken along an imaginary line. A profile measurement is a series of numbers representing elevation relative to some reference level. Generally, profile is measured along two lines per lane, one in each wheel track. Roughness is the summary of variation in surface profile that induces vibrations to the traversing vehicles and is defined over a length of the pavement surface.

The JKR in Malaysia had adopted International roughness index (IRI) of 1.6m/km for four lane highways, 2.5m/km for two way highways and 8m/km for minor roads[6]. The measurements of the Roughness Index (IRI) for a completed pavement surface to be measured in terms of its lane IRI, can be achieved using the Australian Road Research Board (ARRB) walking profiler (WP).The road surface often used by motorist has some frictional properties that is relatively associated with performance, of the road and its safety to the road user[13]. They include the aggregate interstices termed as the microtexture and the coarse component of the texture due to the aggregate particle on the road surface kwon as the macrotexture which are often mentioned as contributory factors to providing comfort to the road user or other wise[10]. Generally the road pavement structure is classified into the sub-grade, sub- base, road base and the surfacing which consist of binding course and wearing course. The wearing course is the exposed topmost layer that provides the travel path, skid resistance, safety and comfort to the road user. In view of this the study investigated specifically the pavement surface roughness of these categories of bitumen pavements, ACW, SMA and SD surfaces For this study, the roughness index of various bituminous test surfaces was determined in accordance to the International roughness index (IRI) standards [4]. The roughness index is a function of the smoothness of pavement, and its comfort, safety and convenience to the road user. The roughness index depends on the road surface roughness, which in turn depends on the finishing of the road surface. A good road is expected to give an improved riding quality, a reduce surface noise, provide minimum delays at road works, and provides enhance deformation resistance[9]. The roughness of different road surface can be determined by various design field testing equipments; these include the Australian roads research board walking profilometer and other Motorize sensors. OBJECTIVE OF THE STUDY The objective of the study is to assess the roughness levels of the various bituminous pavements surfaces in Malaysia. The study deals with measurement of a number of

parameters characterizing the level of roughness of a given stretch of a road surface. SIGNIFICANCE OF THE STUDY The study shall provide useful data of the roughness level of the various bituminous pavement surfaces in Malaysia. The study shall also provide necessary data for determining level of comfort provided by the driving path and the pavement condition. METHODOLOGY The study involved a field survey and testing using the ARRB walking profilometer on the various bituminous pavement surfaces. The walking profiler is an instrument used to produce series of numbers to represent a profile. The profiler works by combining three parameters mainly, a reference elevation; a height relative to the reference; and a longitudinal distance. The International Roughness Index (IRI) is calculated from a measured single longitudinal road profile. First, the profile is smoothened with a moving average of base-length 250 mm[4]. Then, response of a quarter car model, in the form of vertical vibration, is accumulated, which on dividing by the profile length yields IRI. If profile information of two wheel track is available, point-by-point average is considered, and the index is called Half car Roughness Index (HRI)[11]. The study investigated 10 test points per road surface for each of the 6 selected test road surfaces. The test was conducted at an interval of 1km along each test road spanning 10km each, and the total of 60 test points where investigated. These tests were conducted in accordance with the ARRB walking profilometer code [1]. The table below shows the location and categorization of the test roads;

TABLE1. Number of sites categorized by surface type and age Road Surface

Type Age (months)

Jalan Utama-UTM

ACW14 4

Jalan Pontian ACW20 36

Jalan Tebrau 01

SMA14 24

Jalan Tebrau 02

SMA20 24

Jalan Parit yani

SD 60

Jalan Pt. Bulat

SD 56

RESULTS AND DISCUSSIONS All the data collected from the study were analyzed in accordance with the Jabatan Karja Raya (JKR) of Malaysia and the IRI specification. All the data obtained from the study were analyzed and the following results obtained. It should be noted that the following roughness indices obtained from the study could also be used to quantify other pavement surface roughness indices using the Mean Panel Rating (MPR); Profile Index (PI); Ride Number (RN); and Root Mean Square Vertical Acceleration (RMSVA). The roughness index obtained from the study for the various bituminous pavement surfaces investigated indicates that the ACW14 showed the lowest IRI of 1.2m/km indicating a smooth surface, and the surface dressed road surface showed the highest IRI of 8.05m/km indicating a rough surface and the SMA 4.1m/km. The results obtained shows that only the surface dressed roads conforms with the JKR specification [6], with the IRI value of 1.6m/km for 4 lane Highway, 2.5m/km for 2lane Highway and 8m/km for minor roads is specified [2]. Based on the Arahan Teknik (jalan) 8/86 classification of roads in Malaysia, the surface dressed are considered as R2 minor roads with average daily traffic (ADT) volume less than 1000. While the ACW and SMA surfaces in this study are urban arterials U4 with ADT volume less than 3000.

The low value for the ACW makes the surface to be smooth and could be attributed to the age of the pavement and the polishing of the aggregate[13], while in the case of the SMA the surface is rough and generating a high IRI value that exceeds the JKR specification [6]. The SD surface as a minor road [2], generated an IRI that is slidely above the JKR recommendation [2], for such surfaces in Malaysia. For this study, the International Roughness Index (IRI) indices profiler was used, to test the pavement with some of the profiles for the test roads shown below in Fig.1,2 and 3 below; The profile for Jalan UTM-UTAMA in Fig. 1 below

Fig. 1 ACW profile The road profile for the Jalan Tebrau SMA surface could be seen below in Fig. 2;

Fig. 2 SMA profile The road profile of Jalan Parit yaani in Muar is shown below in Fig. 3 as recorded by ARRB walking profiler used in this study.

Fig. 3 SD surface profile All the data obtained from this study were analyzed in accordance with ARRB specification [1] using the formula below and

the average and combine IRI for all the surfaces presented in the tables below Formula used to determine the Roughness Index (IRI) IRI = {IRI1 +IRI2}/2 Where IRI is the International roughness index IRI1 is the first single lane roughness index IRI2 is the second single lane roughness index Table 2 The Average IRI for the test roads

km SD IRI(m/km)

SMA IRI(m/km)

ACW IRI(m/km)

1 3.52 2.3 1.282 5.18 3.4 2.233 6.79 3.3 1.754 4.15 3.6 1.965 8.04 3.7 2.056 5.31 4.1 2.067 8.05 2.02 2.768 7.29 2.50 1.209 4.12 3.22 2.0210 4.43 3.4 3.03 The results obtained from the study were analyzed and the average combine IRI for all the surfaces presented in Table 3 below; Table 3 Average combine IRI for all the test roads Dist (km)

IRI(m/km)

T1 T2 T3 T4 T5Ave.

1 1.62 5 8.3 3.0 3.52 4.312 2.55 2.76 5.1 5.8 5.18 4.293 7.93 6.29 4.51 4.0 6.79 5.924 2.71 5.76 5.8 7.3 4.15 5.125 6.77 6.75 8.5 8.6 8.94 7.936 4.95 3.11 3.6 5.8 5.31 4.587 5.01 4.03 3.0 4.1 8.95 5.038 4.38 3.81 3.5 4.0 7.29 4.609 3.26 4.10 4.6 3.0 4.12 4.4310 4.41 2.70 5.90 5.3 2.83 4.24 From the study the SD surfaces indicated the highest frequency IRI as can be seen in Fig. 4 below

SD Roughness

0

2

4

6

8

10

0 2 4 6 8 10

D i st a nc e ( k m)

Fig. 4 IRI for SD The SMA surfaces generated an IRI value that exceeds the JKR [6], as shown in Fig. 5 below;

SMA Roughness

0

1

2

3

4

5

0 2 4 6 8 10

D i st a nc e ( k m)

Fig. 5 IRI for SMA The ACW generated the least IRI values and could be seen below in Fig. 6

ACW Roughness

0

1

2

3

4

0 5 10

Di st a nc e ( k m)

Fig. 6 IRI for ACW The combine IRI for all the test roads in this study is as shown below in Fig. 7;

Fig. 7 Combine IRI for all the surfaces

CONCLUSION AND RECOMMENDATION The investigation was undertaken with the primary objective to assess the roughness indices of various bituminous surfaces in Johor, Malaysia. The study indicates; The results obtained from the study shows that the surface dressing surfaces gave the highest average IRI value indicating high roughness and the tendency for high vibration and noise. While the SMA and ACW surfaces show a relatively lower IRI indicating a lower vibration, noise and smoother. The study recommends the use of aggregate with high polish stone value (PSV) of 55, aggregate with good interstices and a surface finishing based on the JKR specification. However, the study recommends further investigation on more test surfaces with a propare view of understanding the mean IRI values of these pavement surfaces. ACKNOWLEDGMENT The work described in this paper was carried out by the department of transportation and highway engineering, faculty of civil engineering Universiti Teknologi Malaysia (UTM) in collaboration with Bina Mahsyur Sdn Bhd. and the author will like to thank the supervisors and all those involved in making the study a huge success. REFERENCE ARRB, Walking profiler AG:PT/T450, technology note, 2006. 1-37 Arahan Teknik (jalan) 8/86 classification of roads in Malaysia Awasthi G. and Das A. (2001), Pavement Roughness indices.Transport Research Laboratory TRB vol.84, may 2003. Book of profiling university of Michigan (USA), Sourced (www.umtri.umich.edu/erd/roughness) Beaven P.J and Tubey L.W (1978). The polishing of road stone in peninsular Malaysia. TRRL supplementary report 421.TRRL Crowthorne

Design of flexible Pavements, 2005. JKR specification Ford W.G, Suffian Z and Smith HR (1996). The benefits of using Chipseals in Malaysia. Hasnur R. B (1990). The deterioration of bituminous binders in road surfacings.Sixth, REAA4-10March 1990. Hunter R.N (2000). Asphalt in Road construction. 125-196. Kwang H.J, Morosiuk G. and Emby J. 1992 Assessment of skid resistance and macrotexture of bituminous road surface in Malaysia. Seventh REAA conference, Singapore.443- 449. Sayers M.W. (1995), profiles of Roughness. Transport research board (TRB), Washington D.C no.1260 Walking Profiler G2, ARRB technology user note, 2006. Wilson D.J and Dunn R.C.M (2005). Polishing aggregates to equilibrium skid resistance. 55-71.

MIX DESIGN OF COLD RECYCLED MIX USING DIFFERENT RECYCLED ASPHALT PAVEMENT (RAP) PROPORTION

R. Razali1, Z. Sufian3 Public Work Department, Kuala Lumpur, MALAYSIA M.Y. Abdul Rahman2, J.Ahmad4 & E. Shaffie5 Institute for Infrastructure Engineering and Sustainable Management (IIESM) Faculty of Civil Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, MALAYSIA

ABSTRACT: In Malaysia, pavement recycling technology is relatively new and this technique has become a viable alternative in reducing pavement construction and maintenance cost. In this study, the modified Marshall Test procedure was adopted to identify the mix design parameter for the recycled mixes at various RAP proportions. Four aggregate combinations with various RAP proportions of 0%, 25%, 50% and 75% were used in this study. The optimum moisture content, bitumen emulsion content and cement content were determined at every RAP proportions in the recycled mixes. From the analysis, optimum mix design for each RAP proportion in the recycled mixes were produced based on the laboratory strength parameters such as Marshall Stability, flow and density. Results show that increase in RAP proportion reduces the optimum moisture content and maximum dry density of the recycled mix. The recommended combination and optimum RAP proportion for use in the recycled mix is 25%, 3% of bitumen emulsion and 2% of cement to achieve maximum stability of the recycled mix

Keywords: Bitumen emulsion; optimum moisture content; recycled asphalt pavement; stabilising agent 1. INTRODUCTION Various pavement rehabilitation techniques were adopted by the Public Works Department which included overlay, mill and pave, reconstruction and recycling. Since Malaysia road network extend to approximately 72781.35 kilometers of pave road and 18838.25 kilometers of unpaved roads, the desire to maintain a safe and efficient and cost effective roadway system has led to significant increase in demand to rehabilitate existing pavement (Razali et al., 2010). The rehabilitation method involves haulage of new and old materials at the construction site which may affect construction time. Hence, recycling technique offers better logistic with respect to transportation of materials for disposal.

The reuse of asphalt pavement materials in full-depth recycling (FDR) is cost effective. This technique uses the existing pavement material from the asphaltic layer and a portion of the base materials with addition of additives to produce stabilized base course. These materials are then spread and compacted before asphalt surfacing is applied. The technique of reusing of the old materials in this study is the Cold-In-Place Recycling (CIPR) technique. According to Sufian et al., 2007, the functional and structural performance of the pavement recycling was satisfactory and better than that of the conventional rehabilitated pavements. Furthermore, one of the advantages of the CIPR is cost savings of up to 40% over conventional techniques (Sufian et al., 2005). The concept of recycling technique was first introduced in Malaysia in the mid 80s and since then, has become an alternative and acceptable rehabilitation measures. In this study, an

investigation to determine the best combination and selection of recycled asphalt pavement (RAP) and non asphaltic material mixes to produce quality recycled mix layer was investigated. Development of an optimum mix design for each RAP proportion in the recycled mix were also analysed and discussed in this study.

2. METHODOLOGY In this research, several combinations of RAP and crushed stone aggregates were analysed. The RAP materials were taken from milled old pavement section under rehabilitation while the crushed stone aggregate was taken from Kajang Rock Quarry, Semenyih. Initially, test on the physical properties of the aggregates were conducted so as to comply with the recommendation by Malaysia Road Specification for Cold-in-Place Recycling (REAM, 2005). The material testing was conducted to identify material properties for both RAP and crushed stone aggregate. The mix design study was established to determine the optimum combination of RAP and crushed stone aggregates to produce the recycled layer. This study also investigates the suitable grading of the combined materials, the optimum moisture content, optimum bitumen emulsion content and required cement content. The experimental procedure of this study is as shown in Figure 1. The gradation was selected at the mid range complying with REAM Cold in Place Recycling Specification gradation limit as shown in Figure 2. Generally, the RAP samples have coarser particles and lesser fine particles. The existing RAP grading was modified to fit the designed grading by adding crushed stone aggregates into the existing RAP sample. For

each selected gradation, the RAP materials and crushed stone aggregates was combined in ratios of 0:100, 25:75, 50:50 and 75:25 respectively. The Proctor test is conducted for each combination to determine the optimum moisture content (OMC). Specimens were then prepared at OMC for each RAP proportion to determine the optimum bitumen emulsion and cement content using Marshall method. The Marshall specimen of the combined RAP and crushed stone aggregates were prepared using bitumen emulsion content ranging from 2 to 6 percent by weight in at increments of 1 percent at every stage of cement content of 0, 1.5, 2.0 and 2.5 percent cement content. At different percentage of RAP content, all specimens were tested for Marshall Stability, Density and Flow test for determination of optimum emulsion content and cement content of the recycled mix.

Fig 1: Experimental design flowchart

-20

0

20

40

60

80

100

0.01 0.1 1 10 100

Sieve Size (mm)

Percen

tage

 Passing

 (%)

Design REAM CIPR Envelope  RAP

3. RESULTS AND DISCUSSIONS Table 1 shows the results of RAP and crushed stone aggregate properties which complied with REAM CIPR specification requirements. Results from proctor test showed that the optimum moisture content ranges between 5.2 to 6.5 percent. The dry densities are 1.885 to 2.260 kg/m3. At 0% RAP content, no cement is used and the highest optimum moisture content and maximum dry density achieved was 6.5 % and 2.260 kg/m3. The moisture content decreases as proportion of RAP increases for the recycled mix as shown in Figure 3. This is an indication that moisture is retained in RAP materials and hence moisture content must be controlled during construction.

Table 1. Material properties for RAP and crushed stone

Parameter Crushed stone RAP REAM Specification

Limit Aggregate Impact Value

25.6 21.8 < 30

Aggregate Crushing Value

22.17 15.38 <30

Flakiness Index 16.91 16.69 <30

1.8001.850

1.9001.9502.0002.050

2.1002.1502.200

2.2502.3002.350

1 2 3 4 5 6 7 8 9

Dry

Den

sity

Moisture Content

Dry Density vs Moisture Content

0% RAP 25% RAP 50% RAP 75% RAP

Fig. 3: Dry density vs moisture content of recycled mix

Fig. 2: Design grading for RAP

Determination of optimum moisture content

• Obtain RAP material from the project site • Obtain new materials from quarry

• Sieve analysis • Physical properties of aggregate • Established the design of aggregates grading

Determination of Marshall Properties at various contents of stabilizing agent and RAP proportions:

• Stability, Flow & Density

Establish mix design • Optimum moisture content • Optimum bitumen emulsion content • Optimum cement content • Optimum RAP proportion

RAP: Crushed stone aggregates Proportion

25 : 75 50 : 50 75 : 250 : 100

25 : 75 50 : 50 75 : 250 : 100

Figure 4 shows the result for the Marshall stability varies for different RAP proportions, cement and emulsion content. The peak Marshall stability results obtained for 0% RAP was 46 kN with 1.5% cement and 2.5% emulsion. For both 25% and 50% RAP proportions, interestingly, the peak Marshall stability results were 51 kN. However, the recycled mix with 75% RAP have the lowest strength of between 24 to 27kN even with different variations of cement content added to the mix. Figure 4 shows the Marshall stability results of the recycled mix at different percentage of RAP, cement and emulsion content.

The density of the recycled mix was also investigated as shown in Figure 5. Results showed that control specimen has the highest maximum density of 2.300 kg/m3. The trend shows that as RAP proportion increases, the density decreases. At 25%, 50% and 75% RAP proportion, the maximum density is 2.220, 2.200 and 2.120 kg/m3 respectively.

Fig.5: Density for recycled mix

10.014.018.022.026.030.034.038.042.046.050.054.0

0 1 2 3 4 5 6 7

Stab

ility

(kN

)

Emulsion Content (%)

Stability vs Emulsion Content(0% RAP)

2.5% cement 0% cement 1.5% cement 2% cement

10.014.018.022.026.030.034.038.042.046.050.054.0

0 1 2 3 4 5 6 7

Sta

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Fig.4: OMC and maximum dry density of recycled mix

Results for Marshall flow test show that higher flow values were observed for mix with 0% and 75% RAP proportions compared to recycled mix with 25% and 50% RAP. The Marshall flow values for 0% and 75% RAP mix is 3.5mm and 4.5mm for recycled mix with 50% RAP. However, at 75% RAP proportion, there is an increase in the flow value. Figure 6 shows the result of Marshall flow of the recycled mix.

Fig. 6: Density of recycled mix at various RAP proportions

The mix design selection for recycled mix with various RAP proportions were summarised in Table 2. The use of 25% RAP requires minimum usage of bitumen emulsion but contribute to good stability. Combination of 3% bitumen emulsion and 2% cement is required to achieve maximum stability with 25% RAP proportion in the recycled mix. Table 2. Recycled mix design selection criteria

RAP content

Cement Content

(%)

Stability (kN)

Optimum Moisture Content

(%)

Optimum bitumen emulsion

content (%)0% 1.5 44 6.5 2.5

25% 2.0 49 6.0 3.0

50% 2.0 40 5.3 3.5

75% 1.5 27 5.1 4.0

4. CONCLUSIONS Based on the results obtained from this study, it was also concluded that : • An increase in RAP proportion reduces the

optimum moisture content and maximum dry density of the recycled mix.

• The cement content in recycled mix with higher RAP proportion does not effectively contribute to strength of the mix.

• The recommended combination and optimum RAP proportion for use in the recycled mix is 25%, 3% of bitumen emulsion and 2% of cement to achieve maximum stability of the recycled mix.

REFERENCES

REAM (2005) Specification For Cold In-Place Recycling. Road Engineering Association of Malaysia. p. 13.

R.Razali, M/Y. Abdul Rahman and Z.Sufian (2009) The effects of different RAP Proportion to the performances of cold inplace recycled mix, Proceeding in 13 REAAA Conference in Incheon , South Korea

Zulakmal Sufian, M.Z.H., Mohd Yazip Matori, Nafisah Abdul Aziz (2007) Research on fundamental characteristic of stabilised full depth reclaimed pavement layer. Proceeding, 7th Malaysia Road Conference 2007. Sunway Pyramid Subang, Selangor, Malaysia.

Zulakmal Sufian , N.A.A., Yazip Matori, Mat Zin Hussain (2005) Cold in-place pavement recycling in Malaysia. in 2005 International Symposium On Pavement Recycling. Sao Paolo, Brazil

Flow vs Emulsion Content (0% RAP)

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ID 167: USE OF DYNAMIC MODULUS TEST TO EVALUATE MOISTURE SUSCEPTIBILITY OF ASPHALTIC CONCRETE MIXTURES

J. Ahmad, M.Y. Abd Rahman Institute for Infrastructure Engineering and Sustainable Management (IIESM) Faculty of Civil Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, MALAYSIA

M.R. Hainin Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM-Skudai, Johor, MALAYSIA

M. Hossain

Dept of Civil Engineering, 2124 Fiedler Hall, Kansas State University, Manhattan, KS 66506-5000, USA Email: juraidah@salam.uitm.edu.my

ABSTRACT: Currently, the Modified Lottman test from indirect tensile strength test is widely used to evaluate moisture susceptibility of asphaltic concrete mixtures. In this study, evaluation of moisture induced damage of asphalt concrete mixtures were conducted from dynamic modulus tests in a Simple Performance Tester at different frequencies by applying sinusoidal loading to the specimens in wet and dry conditions. Results showed that there is a good agreement between the tensile strength ratio and dynamic modulus ratio of the wet and dry specimens from both tests. There is also good agreement between unconditioned and conditioned values from the dynamic modulus test. The dynamic modulus values appears to be very close to the line of equality which implies that the results are more consistent and showed less variability than results from the indirect tensile strength test. Results from ANOVA statistical analysis test showed that the SPT dynamic modulus test are more reliable and considers many factors affecting moisture susceptibility of asphaltic mixtures compared to the indirect tensile strength test.

Keywords: Simple Performance Test; Tensile Strength Ratio; Dynamic Modulus Stiffness Ratio  

1.0 INTRODUCTION

An unstable mix that tends to displace laterally and shove rather than compact under roller loads is best to describe what tender mix actually is. Tender hot mix asphalt (HMA) mixes have been observed and experienced by paving contractors for many years.

The tender zone is range of mix temperatures during which the mix exhibits instability during roller action. There have been many possible causes of the tender zone presented including differences in lab and production aging, mix moisture, low dust to asphalt ratio, increased asphalt binder film thickness, and a temperature differential with the lift.

In 1989, Crawford reports the existence of two types of tenderness which first type is characterized by the asphalt mix being difficult to compact when normal construction techniques are used. Re-compaction attempts will result in a decrease in pavement density. The asphalt mixtures being slow setting after construction characterizes the second type of tenderness. This type is sensitive to turning traffic and power steering. It may also lack resistance to critical loading, especially during hot weather.

1.1 Problem Statement and Objective

The possibility of tender mixes existing in pavement construction is high, which can be caused from the improper mix design resulting to lower compaction and high pavement distress. Cooley Jr, et.al (2000) reported that tender mixes are often difficult to compact to the required density. The existence of tender mixes happen

to quite numerous pavement constructions around the world, including in Malaysia.

Furthermore, a remarkable increase in traffic volume has contributed to the severe stripping on highway and main road in Malaysia. Therefore, the evaluation of stripping potential on tender mixes is relevant. As due to that, this research was conducted to evaluate the properties of tender mixes through Marshall Mix Design Test as well as to assess the performance of tender mixes in term of stripping characteristic.

1.2 Scope of Research

The research involves literature review and laboratory works that include designing two ACW20 mixes using Marshall Design. The designation conforms to JKR specification. One mix design was designed with a typical dense graded gradation away from MDL and described as control mix and the other was designed close to MDL to simulate tender mix and described as tender mix. Modified Lottman Test was conducted particularly to evaluate the stripping performance of both mixes. 2. BACKGROUND

2.1 Tender Mix

Tender pavement has been described in many ways and according to Marker, (1977) the following difficulty has been associated with tender pavement:

i. The mix is difficult to roll. ii. The specified density is difficult to achieve.

iii. The pavement ruts after construction is complete.

iv. The pavement is soft after completion and will displace under the heel of a shoe.

STRIPPING PERFORMANCE OF TENDER MIX

E.Shaffie1, Z. Abd.Rahman2 & W. Hashim3 Institute for Infrastructure Engineering and Sustainable Management (IIESM) Faculty of Civil Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, MALAYSIA

ABSTRACT: The possibility of tender mixes existing in pavement construction is high and a remarkable increase in traffic volume has contributed to the severe stripping on highway and main road in Malaysia. This paper with objective to evaluate the stripping characteristic of tender mixes as compared to typical mixes through laboratory tests focusing at HMA ACW 20 of mix type for wearing course. One mix was designed with typical dense graded gradation but away from the maximum density line (MDL) described as control mix. The other mix was designed close to Maximum Density Line (MDL) to simulate tender mix. Both mixes conformed to JKR specification. Marshall samples were prepared in order to determine the optimum bitumen content (OBC) and volumetric properties of both mixtures. Six samples were prepared for the the Modified Lottman Test which measured the stripping. Volumetric properties results indicate that tender mix is not tender as expected due to high voids in the mineral aggregate (VMA) compared to control mix. The Tensile Strength Ratio (TSR) value in the Modified Lottman Test is an indication of the potential for moisture damage. The TSR result for control mix was 87% while tender mix was 78%. In general, the average tensile strength ratio (%TSR) values for control mixes exceeded the minimum requirement. Thus, the control mixes are not susceptible to moisture damage and more resistant with respect to the tensile strength compared to tender mixes.

Keywords: Hot Mix Asphalt (HMA); Tender Mix; Stripping; Tensile Strength Ratio (TSR)

v. The pavement “shoves” under traffic, sometimes months after construction.

vi. The pavement “slips” under traffic, usually fairly soon after construction.

vii. The pavement “scuffs” under power steering or severe braking action.

viii. The pavement indents under a punching load.

Identifying the specific causes of tender mixes is difficult to do. There are a number of items that can cause mixes to be tender and any combination of these items may result in tenderness. Works by Crawford (1989) identified that common causes of tender mixes are any one or any combination of any of the following:

i. Incorrect mix design, ii. Smooth and rounded aggregates,

iii. Moisture in the mix, iv. Abnormally high ambient temperature, v. Asphalt cements characteristics,

vi. Incorrect asphalt cement grade, vii. Incorrect production and construction

techniques, viii. Inadequate bond to underlying layer

2.2 Stripping Stripping is a distress in the asphalt pavement which happens due to moisture susceptibility of the HMA mixture (Roberts et al., 1996). Stripping is defined as the physical separation of the asphalt cement from the aggregate produced by the loss of adhesion between the asphalt cement and the aggregate which is primarily due to the action of water or water vapor (Kenedy, T, et al., 1984). Stripping is the other effect of moisture in the mix where moisture susceptibility is a phenomenon when moisture causes a loss of bond between the aggregate and the asphalt binder. Proper mix design is essential to overcome this moisture susceptibility problem. Even though the mix may be properly design, but not compacted adequately, it may still be susceptible to moisture damage. As such, evaluation of moisture susceptibility of HMA mix design should be done in a situation where moisture is allowed to infiltrate into the air voids of the mixture (Roberts et al., 1996). Several additional factors that contribute to stripping are the use of open-graded asphalt friction, inadequate drying of aggregate, overlays on deteriorated concrete pavements and waterproofing membranes (Hunter and Ksaibati, 2002). Source of moisture in an asphalt pavement can be either external or internal, although generally stripping begins and progress from bottom upwards in sealed pavement layer without physically opening up the pavement. Water can enter the pavement externally from poorly drained areas and from underlying layers due to high ground water sources a shown in Figure 2.1.

Figure 2.1: Sources of water (moisture) in asphalt pavement

structure.(Larry Santuci et al., 2002)

3. METHODOLOGY

This study approach mainly involved experimental work. The study focuses on the properties evaluation and also the rutting and stripping performance evaluation of tender mixes. The Marshall Mix design procedure involvedcareful material selection and volumetric proportioning as a first approach in producing a mix that will perform successfully. The aggregates were obtained from Hanson Quarry Production (HQP), Semenyih and undergone and satisfied the Jabatan Kerja Raya (JKR) material specification test. Laboratory tests to be performed on the aggregates are Specific Gravity and Absorption of Coarse Aggregate (ASTM C127), Specific Gravity and Absorption of Fine Aggregate (ASTM C128) and Sieve Analysis of Fine and Coarse Aggregate (ASTM C136). The gradation will be conduct to determine the grading of the Control mix and Tender mix.

For sample preparation, mix design and compaction and testing, the gradation which compliance with specification were used in this research. Marshall Mix design procedure was used to design asphaltic mixtures. In this phase, selection of gradation and selection of optimum binder content will be determined. The were prepared for each binder content range from 4.5% to 6.0% by weight increment of 0.5%. Loose HMA sample for each mix will then were tested using Maximum Specific Gravity of Bituminous Paving Mixtures (AASHTO T 209-82) and the effective specific gravity of the aggregate will be determined. Volumetric properties Voids in the Total Mix (VTM), Voids in the Mineral Aggregates (VMA) and Voids Filled with Bitumen (VFB) analysis and OBC were obtained using effective specific gravity of aggregate. Then, the optimum cement content was determined using the Marshall method. Finally, the samples were tested for performance evaluation. The performance evaluation performed were stripping test. Samples stripping test were prepared and will compacted to approximately 7 + 1% air voids. The Modified Lottman test (AASHTO T283) was performed

by compacting samples to an air void level of 7%± 0.5%. Three samples were selected as a control and tested without moisture conditioning; and another three samples were selected to be conditioned by saturating with water at 70-80 percent followed by immersing in water for 24 hours at 60ºC in a water bath. The samples were then tested for indirect tensile strength (ITS) by loading the samples at constant head rate (50 mm/minute vertical deformation at 25ºC) and maximum compressive force required to break the specimens were recorded. Tensile Strength Ratio (TSR) results were determined by comparing the indirect tensile strength (ITS) of unconditioned samples with the control samples. Analysis and conclusion on stripping were determined from the result of strength which obtained from the ratio of mean strength of conditioned specimens to the mean strength of dry specimens to measure moisture susceptibility of the mixes. TSR will be used with 80% as the boundary between mixtures resistant and sensitive to moisture (AASHTO, 2005b). The overall experimental procedure of this research work is shown in the Figure 1.

Figure 1: Flowchart of experimental design

4. RESULTS AND DISCUSSIONS 4.1 Marshall Mix Design And Compaction Two gradations were designed for ACW20 conformed to JKR/SPJ/1988 specification. One gradation consist a typical gradation of dense graded design away from maximum density line (MDL) described as control mix. The other gradation was design close to MDL to simulate tender mix described as tender mix. Figure 2 shows the plotted graph for both gradations.

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Figure 2: Gradation chart of control mix and tender mix for ACW20

Volumetric properties of HMA consist of VMA, VTM and VFB. Based on the result obtained, relationship between volumetric properties (Stability, Stiffness, Flow, VTM and VFB) and Binder Content were evaluated. Volumetric properties for ACW 20 control mix and tender mix were calculated using effective specific gravity of the aggregate obtained from Maximum Specific Gravity of Bituminous Paving Mixtures (AASHTO T 209-82) test. The optimum bitumen content (OBC) of the mix was determined from data obtained range of different bitumen content. Series of curves were plotted to get the density, percent of VFB, percent of VTM, Marshall stability and flow value. The OBC were then determined by Asphalt Institute (AI) method which is by the average of selected four series of curve. The OBC determined for control mix and tender mix was performed using AI method. The result of OBC for tender mix was 5.4% higher than control mix which was 5.1%. 4.2 Modified Lottman Test (AASHTO T283) In this study, the samples were tested for both control and tender mixtures. Results of the Modified Lottman test conducted on both mixtures are tabulated in Figures 3 respectively. These figures indicated that unconditioned HMA prepared for control mixes demonstrated higher tensile strength values than tender mixes. For the IDT of unconditioned samples results, control mix has the higher tensile strength value of 1.15 KPa compared to tender mix which has the lower tensile strength value of 1.02 KPa. For conditioned specimens, these figures also indicated that control mix showed better resistance to stripping with respect to the tensile strength compared to tender mixes. For control mix, the IDT of unconditioned samples was 1.15 KPa and for conditioned samples was 1.01 KPa, a decrease of 12% from unconditioned samples. It is evident that the IDT of the mixtures after conditioning will lead to pavement failures. A similar trend was found for tender mixes. Therefore, it could be noted that moisture conditioning significantly affects the performance of the hot mix asphalt.

Gradation Design of ACW20 Control mix and Tender mix

Preparation of Marshall Sample

Sample Preparation for (Modified Lottman Test)

Determine number of compaction to get 7.0 + 1% void.

Conduct Modified Lottman Test

Data Collection and Analysis

Conclusions and Recommendations

Figure 3: Indirect tensile strength of unconditioned and

conditioned samples for both mixtures tested

Moisture Susceptibility criterion for TSR for the moisture susceptibility according to standards of AASHTO T 283 is minimum 80 %. The TSR value in the Modified Lottman Test is an indication of the potential for moisture damage of the mix design. Table 1 shows a comparison of the Tensile Strength Ratio (%TSR) for both mixtures tested. The average tensile strength ratio (%TSR) values for control mixture is 87 percent and 78 percent for Tender mixture. In general, the average tensile strength ratio (%TSR) values for control mixes exceeded the minimum requirement. Thus, the control mixes are not susceptible to moisture damage and more resistant with respect to the tensile strength compared to tender mixes.

Table 1: Modified Lottman Test TSR Values Mix Design Mixture

Control Tender Unconditioned Specimen

Ave. Air Voids(%) 7.0 6.9 Ave .ITS (KPa) 1.15 1.02

Conditioned Specimens Ave. Air Voids (%) 7.0 6.9 Saturation level (%) 72.3 71

Ave. ITS (KPa) 1.00 0.79 Tensile Strength Ratio

(%) 87 78

5. CONCLUSION AND RECOMMENDATION

The TSR value in the modified Lottman test is an indication of the potential for moisture damage. Higher TSR value indicates greater resistance of the mix to moisture damage. A minimum TSR criterion of 80 percent was adopted according to standards of AASHTO T 283(AASHTO, 2005b).

The TSR result for control mix was 87% while tender mix was 78%. In general, the average tensile strength ratio (%TSR) values for control mixes exceeded the minimum requirement. Thus, it can be concluded the control mixes are not susceptible to moisture damage and

more resistant with respect to the tensile strength compared to tender mixes.

It is recommended that other types of mix such as ACW10, ACW14, Gap Graded, Stone Mastic Asphalt (SMA) or Open Graded to be used in future study and designed close to MDL to simulate tender mix. Various type of mix tested will give higher indicative result. 6. REFERENCES American Society of Testing Materials. ASTM C 127

(1992). Standard Test Method for Specific Gravity and Absoprtion of Coarse Aggregates. Philadelphia.

American Society of Testing Materials. ASTM C 128

(1992). Standard Test Method for Specific Gravity and Absoprtion of Fine Aggregates. Philadelphia.

American Society of Testing Materials. ASTM C 136

(1992). Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates. Philadelphia.

Crawford, C.. (1989). Tender Mixes: Probable Cause,

Possible Remedies. NAPA. (108/86) Cooley Jr L.A., Kandhal, P.S., and Mallick R.B.. (2000).

Accelerated Laboratory Rutting Tests: Evaluation of the Asphalt Pavement Analyzer. Transportation Research Board, National Cooperative Highway Research Program Report. (508).

Kennedy, T., F. Roberts, and K. Lee (1984). Evaluating

Moisture Susceptibility of Asphalt Mixtures Using the Texas Boiling Test. Transportation Research Record 968, TRB,National Research Council, Washington, D.C., pp. 45-54.

Hunter E. R. and K. Ksaibati, (2002). Evaluating

Moisture Susceptibility of Asphalt Mixes. Department of Civil and Architectural Engineering, University of Wyoming, Laramie, Wyoming.

Larry Santuci, P.E., LTAP Field Engineer (2002).

Moisture Sensitivity of Asphalt Pavements.Technology Transfer Program and Pavement Specialist, Pavement Research Center, UC Berkeley

Marker, V.. (1977). Tender Mixes: The Causes and

Prevention. Asphalt Institute. No. 168 (IS-168). Roberts, F. L., Kandhal, P. S., Brown, E. R., Lee, D. Y.,

and Kennedy, T. W. (1996). Hot Mix Asphalt Material, Mixture Design, and Construction. 2nd Edition.

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SKID RESISTANCE AND THE EFFECT OF TEMPERATURE Mohd Amin Bin Shafii Postgraduate Student Faculty of Civil Engineering, University Technology of Malaysia amintybe982@gmail.com Dr. Haryati bte Yaacob Senior Lecturer Faculty of Civil Engineering, University Technology of Malaysia haryatiyaacob@utm.my Dr. Mohd Rosli bin Hainin Associate Professor Faculty of Civil Engineering, University Technology of Malaysia mrosli@utm.my

ABSTRACT: Skid resistance is the force developed when a tire that is prevented from rotating slides along the pavement surface. It is the most important characteristic of the road pavement. In the wet conditions, skidding will occur easily when the water film covering the pavement act as lubricant and reduce the friction between the tire and pavement. There are several factors that influence skid resistance such as road pavement texture, aggregate characteristic and surface temperature. Although a number of researcher have attempted to explain and quantify the effect of temperature on pavement skid resistance properties, the result are still unclear. Therefore, the objective of this study is to investigate the effect of pavement surface temperature on the pavement skid resistance properties of different type of mixtures. Besides, this study also wants to investigate whether the type of gradation has a significant effect on skid resistance based on temperature difference. To accomplish the objective of the study, five types of mixture consist of ACW 14, ACW 10, Porous Mix Grade A, Porous Mix Grade B and SMA 14 were prepared. Then, the skid resistance test using British Pendulum Tester was conducted. The test was conducted using heated temperature method and natural temperature method. The results of skid resistance using heated temperature method were compared with the result of skid resistance using natural temperature method. In this study, it is found that temperature has a significant effect on skid resistance value and the relationship between skid resistance value and temperature can be represent using quadratic curve. Based on temperature different, type of gradation has also significant effect to skid resistance value.

Keywords: Skid Resistance, Temperature, British Pendulum Tester, ACW, SMA, Porous Mixture, PTV  

1.0 INTRODUCTION Road accident is a significant problem and a major concern of most highway agencies. Statistics from Polis Diraja Malaysia (PDRM) show that the number of road accidents increased almost every year. The number of road accident increased from 279711 cases in year 2002 to 363319 cases in 2007. Almost 3% of the road accident involves the fatal accident.

There are several factors that contribute to the road accidents. One of the factors is skidding. Skid resistance is the most important characteristic of the road pavement. Skidding will happen when the pavement surface does not provide adequate friction to the tire. In the wet conditions, skidding will occur easily when the water film covering the pavement act as lubricant and reduce the friction between the tire and pavement.

Skid resistance is monitored using different types of skid testing device. The most commonly used device is locked wheel trailer and British Pendulum Tester (BPT). Skid tests are subject to many influential factors, which can be generally classified into three categories: tire-related factors (rubber compound, tread design and condition, inflation pressure, and operating temperature); pavement-related factors (pavement type, microtexture and macrotexture, and surface temperature); and intervening-substance-related factors (quantity of water, presence of loose particulate matter, and oil contaminants). A number of researchers have investigated the effect of temperature on pavement skid resistance properties. One of the problems encountered while reviewing these efforts is that the type of temperature used in

these studies has not been consistent. For example, Runkle and Mahone [4] considered the maximum, minimum and average daily temperatures; Burchett and Rizenbergs [4] considered the maximum and minimum air temperature during a four to eight - week period; and the National Safety Council (1975) used the pavement surface temperature to correlate with pavement friction. Furthermore, the investigations conducted so far have not produced consistent results. While some researchers Runkle and Mahone [4], Burchett and Rizenbergs [4], indicated a statistically significant effect of air or pavement temperature on the skid properties, others Mitchell et al. [4], concluded that the effect was insignificant. 1.1 Problem Statement Environmental factor such as temperature is believed to affect the skid resistance properties of the pavement. Although a number of researcher have attempted to explain and quantify the effect of temperature on pavement skid resistance properties, the result are still unclear. 1.2 Objectives of Study The objective of this study is to investigate the effect of pavement surface temperature on the pavement skid resistance properties of different type of mixtures. Besides, this study also wants to investigate whether the type of gradation has a significant effect on skid resistance based on temperature. To accomplish the objectives of the study, several tests were conducted using asphaltic concrete wearing (ACW) mixture, porous asphalt and stone mastic asphalt (SMA). The test was conducted at several temperatures. 1.3 Scope of Study Due to limitation of time, this study only limited to laboratory test and will not consider field test. The temperature variable only considers pavement surface temperature (sample temperature). 2.0 METHODOLOGY This study was divided into three parts: sample preparation, apparatus that was used and testing procedure. The samples which were prepared consist of ACW 10, ACW 14, Porous Mix Grade A, Porous Mix Grade B and SMA 14. All the samples were prepared based on Marshall Mix Design. Each type of mixture was prepared in two samples for testing. Apparatus that were used in this study are British Pendulum Tester, Infrared Temperature Gun, dryer and water spray. In testing procedure part, the sample was tested using heated temperature method and natural temperature method. At heated temperature, the sample was heated using a dryer to obtain a certain temperature. While, at natural temperature, the sample

was place outside the laboratory at different time in order to obtain different temperature. 2.1 Sample preparation After obtaining the optimum bitumen content for each type of mixture, samples for skid resistance test were prepared. The procedure to prepare the test sample is similar with the procedure to prepare Marshall sample. The difference is only the size of sample and compaction process. The size of sample is 305 mm (1 feet)(width) x 305 mm (1 feet)(length) x 50 mm (depth). In the compaction process, the sample was compacted until it achieves the design air voids of 7 % for ACW 10, ACW 14 and SMA 14 and 20 % for Porous Mix Grade A and Porous Mix Grade B. 2.2 Apparatus 2.2.1 British Pendulum Tester The measurement of skid resistance is measured using British Pendulum Tester. The measurement gives the value in term of British Pendulum Number (BPN). British Pendulum Tester consists of spirit level, leveling screw, pointer, vertical adjustment screw, C unit scale, F unit scale, starting button and rubber slider. 2.2.2 Infrared Temperature Gun Infrared Temperature Gun was used to measure the temperature of the sample during the skid resistance measurement. It only measures the surface temperature of the sample. 2.2.3 Dryer Dryer was used to heat the surface of the samples before the skid resistance test was carried out. 2.2.4 Water Spray Water spray was used to wet the surface of the sample before the skid resistance measurement was taken. 2.3 Testing Procedure At heated temperature, the sample was heated using a dryer at different temperature which is 28°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C and 60°C. Then the skid resistance test was carried out inside the laboratory. At natural temperature, the test was carried out outside the laboratory at different time in order to obtain different temperature. It was done from 9.00 am to 4.00 pm. The measurement of skid resistance is measured using British Pendulum Tester based on BS EN 13036-4:2003. 3.0 RESULT 3.1 Heated Temperature Method

Figure 1 show the graph of skid resistance test result for all type of mixtures using heated temperature method. From the test, initially, the Pendulum Test Value (PTV) decrease as temperature increased. After a certain temperature, PTV increase as temperature increased. For ACW 10 mixture, the lowest PTV is 76 where it happened at the temperature of 36 °C. After the temperature of 36°C, PTV show an increment as the temperature increased. While, for ACW 14 mixture, PTV begin to increase at the temperature of 35 °C with the lowest PTV of 75. The lowest PTV for Porous Mix Grade A, Porous Mix Grade B and SMA 14 mixtures are 83, 84 and 81 respectively. It happened at the temperature of 28 °C, 35 °C and 34 °C. Based on Figure 1, for all types of mixtures, generally the turning point temperatures where PTV begins to increase are around 28 °C to 36 °C.

Fig. 1. Graph of Pendulum Test Value (PTV) versus Temperature for all types of mixtures using heated temperature method 3.2 Natural Temperature Method The graph of skid resistance test result for all type of mixtures using natural temperature method is shown in Figure 2. Similarly with the result of skid resistance test using heated temperature method, the result of skid resistance test using natural temperature method also shown the same patterns of curve where the graph for Pendulum Test Value (PTV) versus temperature can be represented using quadratic curve. The lowest Pendulum Test Value (PTV) for ACW 10, ACW 14, Porous Mix Grade A, Porous Mix Grade B and SMA 14 mixtures are 66, 62, 86, 75 and 79. While the temperature where the PTV begin to increase are 38 °C, 42 °C, 39 °C, 39 °C and 36 °C respectively. From

the test, these temperatures occur around 11.00 AM to 12.00 noon.

Fig. 2. Graph of Pendulum Test Value (PTV) versus Temperature for all types of mixtures using natural temperature method. 4.0 DISCUSSION Based on Figure 1 and Figure 2, generally, it shows that the graph of Pendulum Test Value (PTV) versus temperature can be represented using quadratic curve where at the initial stage, PTV decrease as temperature increased. After a certain temperature, PTV increase as temperature increased. This phenomenon happened may be due to some of the bitumen was pill out at higher temperature. When some of the bitumen was pills out, it will leave the aggregate with rough surface. The aggregate with rough surface will increase the Pendulum Test Value (PTV). In this study, comparison between the result using heated temperature method and natural temperature method show that, PTV using heated temperature are more consistent and have smoother curve pattern compared with the result obtained using natural temperature method. This result happened may be due to the heated temperature method which has more consistent temperature than natural temperature method. Furthermore, it is found that, based on temperature difference, the type of aggregate gradation has significant effect on the Pendulum Test Value (PTV) where Porous Mix Grade A has the highest PTV value followed by Porous Mix Grade B, SMA 14, ACW 14 and ACW 10. In addition, type of aggregate

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 Test Value

 (PTV

)

Temperature ° C

Pendulum Test Value (PTV) versus Temperature

ACW 10ACW 14Porous Grade APorous Grade BSMA 14

gradation has no significant effect on the pattern of the graph (PTV versus Temperature). From the figure, it shows that the pattern of the graph, Pendulum Test Value (PTV) versus temperature almost similar for all types of mixtures. 5.0 CONCLUSION The summaries of findings are:

i) The relationship between skid resistance value (Pendulum Test Value (PTV)) and temperature can be conclude as quadratic curve where at early stage, skid resistance value will decrease as temperature increased but after certain temperature, skid resistance value will increase as temperature increase.

ii) The skid resistance test using heated temperature method has more consistent value compared to the result using natural temperature method as we can see from the graph of skid resistance value versus temperature where all type of mix using heated temperature method has more than 85% R2 value.

iii) Porous Mix Grade A and Porous Mix Grade B has the highest Pendulum Test Value (PTV) at the highest temperature where the PTV for Porous Mix Grade A and Porous Mix Grade B using heated temperature method are 103 and 97 respectively.

iv) Based on temperature difference, the type of aggregate gradation (dense graded, open graded and gap graded) has significant effect on the Pendulum Test Value (PTV) but has no significant effect on the pattern of the graph where we can see the graph of Pendulum Test Value (PTV) versus temperature for all type of mixtures has similar shape (quadratic curve).

From this study, it was concluded that temperature has a significant effect on skid resistance value and the relationship between skid resistance value and temperature can be represent using quadratic curve. But, based on temperature different, type of gradation has significant effect to skid resistance value. 6.0 REFERENCES British Standard Institution (2003). BS EN 13036-4.

Method for measurement of slip/skid resistance of a surface-The pendulum test. London: British Standard Institution

Burchett J. L and R. L. Rizenbergs (1980) “Seasonal Variations in the Skid Resistance of Pavements in Kentucky.” Transportation Research Record, No. 788, 12p.

Gordon Wells. (1970). Traffic Engineering an

Introduction. Great Britain: Charles Griffin and Company Ltd.

Ibrahim M. Asi (2007). Evaluating skid resistance of different asphalt concrete mixes. Building and Environment, 42, 325–329. Elselvier Ltd.

Pavement Management Committee. (1977). Pavement management guide. Canada: Roads and Transportation Association of Canada

Subhi M. Bazlamit, Farhad Reza (2005). Changes in Asphalt Pavement Friction Components and Adjustment of Skid Number for Temperature. Journal of Transportation Engineering, Vol. 131.ASCE

Yingjian Luo (2003). Effect of Pavement Temperature on Frictional Properties of Hot-Mix-Asphalt Pavement Surfaces at the Virginia Smart Road. Master of Science, Virginia Polytechnic Institute and State University, United State of America.

.

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1. INTRODUCTION

In general, there are two main pavement types which are flexible and rigid pavement. Rigid or concrete pavement is more complex to build, which required more specialized equipment. The current preference within the road industry is to flexible and composite road pavement. Flexible pavement bituminous surfacing while rigid pavement consists of a thick concrete top surface. In addition, composite pavement is where a flexible layer has been added on top of the surface of a rigid road, or where a concrete layer exists below a bitumen top surface (Smith, 2007).

Rigid pavement design has over the years become a more important part for the promoting of concrete roads. High

capital cost is balanced by the less cost of pavement maintenance and longer design period. However, proper design of rigid pavement needs to be emphasized in order to avoid lack of performance of rigid pavement (Griffith and Thom, 2007). Moreover, time taken during design stage may also increase the capital cost. Although, many software application have been introduced to counter the problems, but it may be expensive, not user-friendly enough and not allow the users to compare which is more economical in term of the thickness between the design methods. Due to that, this study will concentrate on the development of software that may help the design engineer as well as the contractor to choose the best pavement in term of design and cost.

DEVELOPMENT OF SOFTWARE FOR RIGID PAVEMENT THICKNESS DESIGN

Mohd Khairul Idham bin Mohd Satar Faculty of Civil Engineering, University Technology of Malaysia khairulidham@utm.my

Mohd Rosli bin Hainin Faculty of Civil Engineering, University Technology of Malaysia mrosli@utm.my

Haryati bt. Yaacob Faculty of Civil Engineering, University Technology of Malaysia haryatiyaacob@utm.my

Dorina anak Astana Faculty of Civil Engineering, University Technology of Malaysia dorina@utm.my

Nur Izzi bin Md. Yusoff Faculty of Engineering and Built Environment, National University of Malaysia evxnim@nottingham.ac.uk ABSTRACT: Rigid pavement is a frequently misunderstood form of construction. Many people assume that the rigid pavement is costly and not effective. However, it has been proved that it is good in term of the strength and ability to cater high traffic load compare to flexible pavement. However, in order to have good rigid pavement, the design procedures of the pavement should be properly applied. The vital issue in pavement design is thickness. There are two main approaches of design the rigid pavement thickness which are Portland Cement Association (PCA) method and American Association of States Highway and Transportation Officials (AASHTO) method. However, both methods are difficult to conduct manually and produced inaccuracy result. The difficulties can be expressed in term of time consuming and tedious calculation. Hence, it is very important to computerize the methods in order to make it more accurate and quicker. Although there are available software in the market but the software may not be user-friendly enough. It also does not allow the user to compare between the methods. Generally, both methods have their own concept but there are still several same parameters considered. Therefore, the significance comparison between both methods can be done to select most economical pavement thickness design. Microsoft Visual Basic 6.0 was the tools used to develop the new software. Software named as AnP Pave was successfully developed and the verification result shows that there are only small differences between the software and manual calculation. A part from that, by using this software, the most economical method was easily obtained. AASHTO method is more economical for the lower traffic loading; otherwise PCA method is more economical for the higher traffic loading.

Keywords: Rigid pavement thickness; PCA method; AASHTO method; software; Visual Basic (VB)

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1.1. Objectives of the Study

i) To analyze and recognize the difference between Portland Cement Association (PCA) method and American Association of State Highway and Transportation Officials (AASHTO) method in term of the concept and parameters used.

ii) To develop user-friendly software that allows the design engineer to compare the results between two methods.

2. METHODOLOGY

To archive the objectives of the study, three major steps need to be gone through which were preliminary study on the manual design calculation, development of the software and verification stage.

2.1 Manual Design Calculation

By manual design calculation, several parameters need to be considered and carried out before calculate the thickness design. Based on PCA method the design procedures are as follows: i) Designer assigns input parameters ii) Select trial thickness iii) Fatigue analysis iv) Erosion analysis v) Increase trial thickness minimum that just exceeds

100% for both fatigue and erosion The fatigue and erosion analysis are carried out to determine the equivalent stress, erosion factor, and stress ratio factor for single and tandem axles. The parameters are determined through specific tables and chart produced by PCA based on information such as type of pavement, sub-base type, concrete modulus of rupture, modulus of sub-grade reaction, k and traffic data(Huang, 2004). It takes about 170 calculations (C&CA, 2008). Meanwhile, AASHTO method is established based on Eq. (1) below: [2]

where:

= traffic carried in ESALs

Eq. (1) is difficult to solve directly. The AASHTO provides a nomograph for determining the solution. However, the accuracy of the design may be query due to the human error.

2.2 Software Solution

Programming software used in this study was Microsoft Visual Basic 6.0. Selection of Microsoft Visual Basic as a programming tool is because it can be integrated with other Microsoft program especially Microsoft Excel. Moreover, programmers are able to create their own interface for the software.

2.3 Verification Stage

Verification of new design software is compulsory in order to ensure the software produce the same output compare with manual design. The simple term is to ensure no hesitation output by the software.

3. FINDINGS AND DISCUSSION

Table 1 shows the input variables or parameters required in AASHTO and PCA methods. (Guell, 1985).

Table 1. Input Parameters for AASHTO and PCA method

PARAMETER AASHTO METHOD PCA METHOD

Traffic Total 18-kip ESAL Application, W18

Total trucks

Concrete Elastic Modulus, Ec

User defined 4x106 psi (27600 MPa)

Modulus of Subgrade Reaction, k

User defined User defined

Modulus of Rupture, Sc

User defined User defined

Load Transfer

User defined • Coefficient, J

(Usually: 3.2 – 4.2)

User defined • Dowel /

Aggregate-interlock

• Shoulder / No shoulder

Drainage Coefficient, Cd

User defined -

Design Serviceability Loss, ΔPSI

User defined -

Overall Standard Deviation, So

User defined -

Reliability, R or User defined -

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Standard Normal Deviate, ZR

Load Safety Factor (LSF) -

Based on type of road and amount of trucks (1 - 1.3)

Several parameters are also not considered in PCA method which are: i) Drainage Coefficient, Cd ii) Design Serviceability Loss, ΔPSI iii) Overall Standard Deviation, So iv) Reliability, R or v) Standard Normal Deviate, ZR

3.1 AnP Pave Software

The new software was developed after recognized and distinguished the parameters in AASHTO and PCA method The software called as AnP Pave Software developed comprises of several menus and forms. The menus and forms are: i) Design Method Selection Menu ii) Traffic Input Data Form iii) PCA Method - Input Data Form iv) PCA Method - Axle Data Form v) PCA Method – Result vi) AASHTO Method – Input Data Form vii) ASHTO Method – Result viii) AASHTO And PCA Results Comparison

3.2 Verification of AnP Pave Software

Validation of new design software is compulsory in order to ensure the software produce the same output compare with manual design. The simple term is to ensure no hesitation output by the software. In this verification stage, the data used are as shown in Table 2.

Table 2. Input parameters for verification

PARAMETER AASHTO METHOD

PCA METHOD

Traffic Design ESAL =5.0 x106

ADTT = 117 trucks/day/direction or Design Traffic = 1.1 x 106

Concrete Elastic Modulus, Ec

4x106 psi 4x106 psi

Modulus of Subgrade Reaction, k

100 pci 100 pci

Modulus of Rupture, Sc

650 psi 650 psi

Load Transfer J = 3.2 Dowelled joint without shoulder

Drainage Coefficient, Cd

1.0 -

Design Serviceability Loss, ΔPSI

1.7 -

Overall Standard Deviation, So

0.29 -

Reliability, R or Standard Normal Deviate, ZR

R = 95% or ZR = -1.645 -

Load Safety Factor (LSF) - 1.2

Other general data required are: Design Period : 20 years Annual Growth Rate : 5 % Percentage of Truck : 13 % Proportion of truck in design lane : 0.81 Table 3 and Table 4 show all verification result done for AnP Pave Software.

Table 3. Comparison of for AASHTO and PCA method

Table 4. Comparison of total fatigue and erosion for PCA method using AnP Pave and manual calculation

TRIAL THICKNESS = 9.5 in FATIGUE (%)

EROSION (%)

SOFTWARE 54.6 4.8 MANUAL 50.9 4.6

3.3 Comparison of Thickness Due to Traffic

Economical pavement thickness corresponded to the thickness itself. The thicker the thickness means more expensive the pavement. Therefore, to have an economical thickness, comparison between the methods need to be performed. According to Guell, it is difficult to compare between AASHTO and PCA method. However the most logical comparison can be expressed as shown in Figure 1 and Figure 2 below. All the thickness values were obtained from AnP Pave Software.

AASHTO METHOD

PCA METHOD

SOFTWARE

Using AASHTO data 9.49 9.29

Using PCA data 9.42 9.29

MANUAL 9.50

9.50 (allowable fatigue and

erosion <100)

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Fig. 1. Comparison of thickness due to traffic for dowelled pavement

Fig. 2. Comparison of thickness due to traffic for aggregate interlocked pavement

4. CONCLUSION

It can be concluded that although PCA and AASHTO have their own concept and parameters, there are also same parameters considered in the design. The parameters are modulus of subgrade reaction (k), modulus of rupture (sc) and traffic. Based on the verification result, it shows that

the software can be used as tools to design concrete pavement easier, faster and more accurate. Additionally, comparison of the thickness due to traffic loading show that, it is more economical to used AASHTO method if the traffic is lower since the thickness is lower compare with PCA method thickness. However, for higher traffic, it is more economical to construct using PCA method because the AASHTO will produce thicker pavement.

REFERENCES

Cement and Concrete Association Malaysia (C&CA), Course on Concrete Road Pavement Design 2008, 17-18th November 2008. Kuala Lumpur

David L. Guell, (1985). Comparison of Two Rigid Pavement Design Methods. Journal of Transportation Engineering. 111, 607-617.

Griffiths G. and Thom N. (2007). Concrete Pavement Design Guidance Notes. United States. Taylor & Francis.

Huang, Y.H (2004). Pavement Analysis and Design.2nd Ed. Upper Saddle River, NJ: Prentice-Hall.

Peter Smith (2007). http://incatrad.com, Road Structure. Date accessed: 2nd March 2009.

AASHTO  PCA

J= 3.2 Dowelled Without Shoulder Load Distribution = Category 3 

AASHTO  PCA

J= 4.2 Aggregate Interlocked Without Shoulder Load Distribution = Category 3 

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1. INTRODUCTION Over the years, road structures have deteriorated more rapidly than expected due to increases in traffic volume, axle loading and tyre pressure and insufficient degree of maintenance. In Malaysia, rutting is the dominant deterioration problem because of hot climate. In majority of local traffic and environmental conditions, the mixes using unmodified asphalt show satisfactory performance. However, under adverse traffic conditions and exacerbated by high surfacing temperature experienced throughout the year, surface distress become apparent in relatively short period of time [1]. Therefore, the existing pavement should be improved in terms of rutting resistance. In order to counteract such deterioration such as rutting and fatigue cracking, several measures are continuously taken, such as improving the pavement quality and its structure design methods. In order to obtain the better pavement, the bitumen properties as one of the important component in the mixture itself must be enhanced. One possible source of improvement is provided by modifying present bitumen properties which capable of incorporating weathering and deformation problems, which may result in better road surface layer. Recently, the substitution of industrial material by industrial by-product (recycled) polymers such as epoxy to modify asphalt properties has been taken into consideration, in

order to reduce modification costs and obtain environmental benefits. On the other hand, from an environmental and economic standpoint, the use of a waste material for replacing pure polymers is the most preferential recycling method, resulting greater cost savings, lower energy consumption and lower environmental pollution [2]. Study done by Downes et.al [3] shows that the epoxy modified bitumen is twelve times the cost of normal bitumen. However, the performance of the product in terms of fatigue and permanent deformation would appear to be in excess of ten times than normal AC. Recently, the substitution of industrial material by industrial by-product (recycled) polymers such as epoxy to modify bitumen and ac properties has been taken into consideration, in order to reduce modification costs and obtain environmental benefits. Therefore, this study of bitumen modification was carried out using epoxy by-product. The aim of this study is to determine the extent of epoxy potential as bitumen modifier. 2. EXPERIMENTAL PROGRAM This study was conducted using bitumen 80/100 PEN. The epoxy was grind to finer size of passing 0.15 mm to obtain well-dispersed blend with bitumen. The method used to accomplish the blend was a wet process. The epoxy was blended for approximately 60 minutes at 160 °C.

THE EFFECT OF EPOXY BITUMEN MODIFICATION ON HOT MIX ASPHALT PROPERTIES AND RUT RESISTANCE

Dorina anak Astana Faculty of Civil Engineering, Universiti Teknologi Malaysia dorina@utm.my

Mohd Rosli bin Hainin Faculty of Civil Engineering, Universiti Teknologi Malaysia mrosli@utm.my

Che Ros bin Ismail Faculty of Civil Engineering, Universiti Teknologi Malaysia cheros@utm.my

Mohd. Khairul Idham bin Mohd Satar Faculty of Civil Engineering, Universiti Teknologi Malaysia khairulidham@utm.my

ABSTRACT: Currently, the studies on improvement of highway material quality have been done using bitumen modification since bitumen is sensitive to temperature susceptibility and rate of loading. Thus, bitumen modification has become trigger factors to improve the hot mix asphalt (HMA) properties and rut resistance. In this study, epoxy has been used as bitumen modifier. In this study, an attempt was made to evaluate the relationships between Penetration, Softening Point and Penetration Index (PI) of the bitumen with the certain amount of epoxy in bitumen. Besides, this study also determine the extent of epoxy in rut resistance of asphaltic concrete.

Keywords: Modified Bitumen, Polymer Modified Bitumen, Epoxy, Hot Mix Asphalt, Rut Resistance

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2.1. Epoxy The epoxy used in this study is a by-product from electronic manufacturing process. The epoxy used in this study is shown in figure 1 and 2 below. It is categorized as thermoplastic polymer [4]. Epoxy exhibit hardness, strength and heat resistance. Generally, thermoplastic stiffen the bitumen. The physical properties of epoxy are shown in Table 1 below.

Fig. 1. Epoxy (before grind)

Fig. 2. Fine epoxy (after grind)

Table 1. Physical properties of epoxy Property Unit Value Density mg/m3 2.100 Tensile Modulus GPa 14.3 Tensile Strength MPa 39.4 Service Temperature °C 260 Hardness - D55-65 Linear Mold Shrinkage mm/mm 0.002 2.2. Testing Program Applied to the Bitumen The physical properties of bitumen that are most important to hot mix paving are penetration and softening point. The tests were done at various epoxy concentration; 0% to 24%

with increment of 4% by weight of bitumen. In this study, the following tests are conducted on both normal and modified bitumen: a) Penetration tests performed at different concentration

of epoxy with a 100 g load applied for 5 seconds according to AASHTO T-49 procedures.

b) Softening points tests at different epoxy content based on the ring and ball method. These tests were done following the AASHTO T-53 procedures.

Each test is repeated at a least three times for each epoxy contents. From these tests, the penetration index (PI) was calculated by using the following equation:

. .

(1) where P is the penetration values and SP is softening point. 2.3 Testing Program Applied to the Asphaltic Concrete AC should be design to meet the necessary properties based on ACW14 mix design according to JKR/SPJ/2007. The bitumen content used were 4.5% to 6.5% with increment of 0.5% by weight of mix. The amount of epoxy used were the optimum epoxy content obtained from PI values. In this study, HMAs were characterised through Marshall test. The dimensions of the cylindrical samples are 100 mm diameter by 63.5 mm height. The samples were compacted by applying 75 blows on each side at 135 °C in accordance with ASTM D 1559 then stored at ambient temperature for one day. Each test is repeated at a least three times for each bitumen contents. The Marshall properties such as density, VTM, VFB, stability, flow and stiffness then been obtained. The optimum bitumen content also been obtained. The three-wheel immersion tracking machine been used to determine the rutting resistance at 60 °C. The bitumen and epoxy content used were the optimum bitumen from Marshall test and optimum epoxy content from PI values. The dimensions of the samples are 407 x 90 x 137 mm. The samples were compacted by applying 500 roller passes the above surface of the samples. Each test is repeated at a least three times for each normal and epoxy modified ACs. 3. FINDINGS AND DISCUSSION The optimum bitumen content for Bit. A is 5.1% and Bit. B is 5.0%. Meanwhile, the optimum epoxy content used in this study are 29% by weight of Bit. A and 38% by weight of Bit B. 3.1. Penetration and Softening Point The standard penetration test was conducted on normal and modified bitumen and the results are shown in Figure 3. Penetration for normal Bit. A and Bit. B are 81.1 and 81.2 PEN. The penetration value for modified bitumen for both sources decrease as the content of epoxy increases. The bitumen becomes more viscous and harder, which would be

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useful to obtain stiffer AC. Therefore, the internal strength of the bitumen increases. This is an indication of an enhanced resistance against permanent deformation of the modified AC during their service life in pavement. The modified Bit. B is harder compared to modified Bit. A. Therefore, it is expected that asphaltic concrete using modified Bit. B is more resistance to rutting formation.

Fig. 3. Penetration versus epoxy content The results for softening point are shown in Figure 4. There are almost linear relationship between the epoxy content and softening point for both type of bitumen. As the epoxy content increases, the softening point of bitumen also increases. It shows that both of modified bitumen becomes less susceptible to temperature changes as the content of epoxy increases. The normal temperature in Malaysia is 23°C to 33°C with average of 27°C. But in the afternoon, the temperature of the pavement can reach around 50°C. According to Figure 2, the temperature of modified bitumen is above 52°C. Therefore, at 50°C, the bitumen still does not soften. Thus, the epoxy modified bitumen helps to resist the deformation in pavement. 3.2 Penetration Index (PI) The suitable bitumen PI for construction is between -1 and 1. Figure 5 shows the PI pattern for both Bit. A and Bit. B. There is significant increase of the PI as the epoxy content increases. The optimum epoxy content (when PI = 0) for Bit. A and Bit. B are 29% and 38% by weight of bitumen. The decrease in penetration and increase in softening point indicate an increase in hardness of the modified bitumen. Hence, in addition to the increase in hardness, the PI increases revealing that epoxy additions enhance the temperature susceptibility of the bitumen.

Fig. 4. Softening point versus epoxy content

Fig. 5. Penetration Index versus epoxy content 3.3. Marshall Mix Design Properties The Marshall properties for normal and modified bitumen are as shown in Table 2. These results show that the addition of epoxy generally decreases the AC density, voids filled with bitumen (VFB), stability and stiffness. However, it increases the voids in total mix (VTM) and flow. Only slight differences are apparent in the density, VFB and VTM properties of AC using modified bitumen compared to normal AC. Table 2. Marshall properties of normal and modified bitumen

Properties Bit. A Bit. B N M N M

Density kg/cm3 2.326 2.321 2.323 2.313 VFB % 78 76 77 75.5 VTM % 3.2 3.5 3.4 3.7 Flow mm 1.65 2.70 1.70 2.05 Stability N 15100 14200 14100 13500 Stiffness N/mm 9000 5600 8600 6530 Note: N – normal bitumen, M – modified bitumen

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3.4. Rut Resistance The graphs of rut depth against number of cycle are as shown in Figure 6 and 7. Epoxy modified AC produce lower rut depth compared to normal AC. This shows that epoxy modified AC have higher rut resistance. Since the epoxy offers greater hardness, the modified asphaltic concrete generally will increased the rutting resistance. The figures also show that normal and modified AC using Bit. A have lower rut depth and higher rut resistance compared to AC using Bit. B. The maximum rate of rutting for modified AC is lower compared to normal AC. In Figure 6, the rut depth of epoxy modified asphaltic concrete A increased abruptly compared to normal modified asphaltic concrete A. This might be due to the problem during compaction, which affect to the composition of mix particles.

Fig. 6. Rut depth versus no. of cycle for AC using Bit. A

Fig. 7. Rut depth versus no. of cycle for AC using Bit. B 5. CONCLUSION The bitumen modifications using epoxy has been proven to enhance performance in bitumen and AC. There is an improvement in bitumen penetration index to make it more preferable to be used during construction. Besides, the epoxy offer improved rutting performance over the AC using normal bitumen, which will increase life cycle.

However, there are only slight differences in terms of Marshall properties between normal and modified AC. Overall, epoxy is suitable to be used as bitumen modifier. REFERENCES 1. Mohd Hizam Harun (1996). The Performance of

Bituminous Binders in Malaysia. Proceedings of the 1996 Malaysian Road Congress on Innovation in Road Building. 11 June. Malaysia, 55-62.

2. Low Kaw S., Cavaliere, M. G. Tan Nai L., and Mohd Adib Awang Noh. (1995). Polymer Modified Bituminous Binder for Road and Airfield Construction. Proceedings of the 1995 8th Conference of Road Engineering.. 17-21 April. Association of Asia and Australasia. Taipei, China: 295-300.

3. Downes, M. J. W., Koole, R. C., Mulder, E. A. and Graham, W. E. (1988). Some Proven New Binders and Their Cost-Effectiveness. Proceedings of the 1988 7th International Asphalt Conference on Asphalt. 7-11 August. Brisbane, Australia: 119-132.

4. Myer, K. (2002). Handbook of Materials Selection: Chapter 11. New York: John Wiley & Sons Publisher.

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1.0 INTRODUCTION

Nanotechnology has recently become one of the major interests among experts, engineers, media as well as public community. It is essentially about new ways of making things through understanding and control over the fundamental building blocks (i.e. atoms, molecules and nanostructures) of all physical things. This is likely to change the way almost everything is designed and made. With the backing of unprecedented funding, nanotechnology is fast emerging as the industrial revolution of the 21st century (Zhu, W., Bartos, P. and Porro, A., 2004, Glenn, J. C., 2006, Mamalis, A. G., 2007). Advances in nanotechnology promise to have major impacts on our life in the coming decades. Since the 1990s there has been a very rapid increase in the implementation of nanotechnologies and promises breakthroughs in such areas as materials and construction, manufacturing, nanoelectronics and computer information technology, OPPP

medicine and healthcare, aeronautics and space exploration, environment and energy, biotechnology and agriculture, national security, and science and education (Zhu, W., Bartos, P. and Porro, A., 2004, Konstantin Sobolev, I. F., Roman Hermosillo, Leticia M. Torres-Martínez, 2006, Sahoo, S. K., Parveen, S. and Panda, J. J., 2007, Salerno, M., Landoni, P. and Verganti, R., 2008, Tegart, G., 2009). 1.1 Overview of nanotechnology Even though addition of polymers is a common method applied for pavement improvement; it will be an eager among experts and engineers to explore the performance of pavement properties ranging from macro and meso scales down to the nano scales. Figure 1 illustrates the evolution of length scales of flexible pavement material in macro scale and to quantum scales (You, Z., Mills-Beale, J., Foley, J. M. et al., 2010).

EXPLORING THE USAGE OF NANOPARTICLES IN PAVEMENT ENGINEERING Mohd Ezree Abdullah*, K.A. Zamhari**, M.K. Shamshuddin*** Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), Malaysia *ezree@uthm.edu.my, **kemas@uthm.edu.my, ***mkamal@uthm.edu.my

Nafarizal Nayan Faculty of Electric and Electronic Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), Malaysia nafa@uthm.edu.my

Mohd Rosli Hainin Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM), Malaysia roslihainin@gmail.com

ABSTRACT: Recently, nanotechnology has become a great interest among researchers to explore into new areas with high growth potential and competitive edge. Nanotechnology deals with blending, processing and applying of particles with microscopic scale smaller than 100 nanometer into current construction material and practices. This paper explains an overview of nanotechnology and its historical development, structural characterization, types of nanoparticles used as well as the applications of nanoparticles in pavement pavement engineering. It is believed that advances usage in nanotechnology promise to have major impacts on pavement sustainability in future. Keywords: Nanotechnology, nanoparticles, pavement engineering

Fig. 1. Evolution image of different asphalt dimensions (You, Z., Mills-Beale, J., Foley, J. M. et al., 2010).

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Nanotechnology can be defined as the science and engineering involved in the design, synthesis, characterization and application of materials and devices whose smallest functional organization in at least one dimension is on the nanometer scale which is one billionth of a meter (10-9 m) (Sahoo, S. K., Parveen, S. and Panda, J. J., 2007). In general, nanomaterials may have globular, plate-like, rod like or more complex geometries. Near-spherical particles which are smaller than 10 nm are typically called clusters. The number of atoms in a cluster increases greatly with its diameter. At 1 nm diameter there are 13 atoms in a cluster and at 100 nm diameter the cluster that can accommodate more than 107 atoms. Clusters may have a symmetrical structure which is, however, often different in symmetry from that of the bulk. They may also have an irregular or amorphous shape. As the number of atoms in a cluster increases, there is a critical size which a particular bond geometry that is characteristic of the extended (bulk) solid (Glenn, J. C., 2006, Roduner, E., 2006). Besides that, nanoparticles also have a high surface area to volume ratio which providing the potential for tremendous chemical reactivity. Figure 2 shows particle size and specific surface area related to concrete materials and the size of nanoparticles in comparison with other small particles is shown in Figure 3.

Fig. 2. Particle size and specific surface area related to concrete materials. Adapted from (Konstantin Sobolev, I. F., Roman Hermosillo, Leticia M. Torres-Martínez, 2006) More than anything else, nanotechnology is being considered as a key technology and allowing us to do new things in almost every conceivable technological discipline. This transformation can change to almost all aspects of human society due to the development of sustainability material, construction and many other technological advances (Zhu, W., Bartos, P. and Porro, A., 2004, Miyazaki, K. and Islam, N., 2007, Sahoo, S. K., Parveen, S. and Panda, J. J., 2007, Bystrzejewska-Piotrowska, G., Golimowski, J. and Urban, P. L., 2009, Sanchez, F. and Sobolev, K., 2010).

Fig. 3. Size scale and examples of micro- and nanocomponents. Adapted from (Mamalis, A. G., 2007)

1.2 Historical development of nanotechnology The concept of nanotechnology came about by The Nobel Prize winning physicist Richard Feynman’s lecture in 1959 called ‘There’s Plenty of Room at the Bottom’. He said that nothing in the laws of physics prevented us from arranging atoms the way we want. He even pointed to a development pathway: machines that would make smaller machines suitable for making yet smaller machines, and the classic

3

‘top down’ approach. The term nanotechnology was first introduced by a Japanese engineer, Norio Taniguchi. He described the precision manufacture of parts with finishes and tolerances in the range of 0.1 nm to 100 nm. The term originally implied a new technology that went beyond controlling materials and engineering on the micrometer scale. Then, in 1981, Drexler pointed out a new approach which is more relate with the meaning and application today. He corresponds to the atom-by-atom manipulative, hardtech processing methodology (Zhu, W., Bartos, P. and Porro, A., 2004, Cao, G., 2006, Roduner, E., 2006, Sahoo, S. K., Parveen, S. and Panda, J. J., 2007, Salerno, M., Landoni, P. and Verganti, R., 2008, Steyn, W. J. v., 2008, Islam, N. and Miyazaki, K., 2010, Pacheco-Torgal, F. and Jalali, S., 2010, Sanchez, F. and Sobolev, K., 2010). Today, the growing interest in nanostructured materials is the natural consequence of advances and refinements of knowledge about the creative manipulation of materials on the nanometer scale in order to perform functions or obtain characteristics which could not otherwise be achieved. (Zhu, W., Bartos, P. and Porro, A., 2004, Uskokovic, V., 2007) stated that the more precisely nanomaterial properties are magnified, the more unusual and unexpected features emerge. 2.0 STRUCTURAL CHARACTERIZATION OF

NANOPARTICLES

One of the critical challenges faced by researches in the nanotechnology area is the understanding of instrumentation with various potential of applications to observe, measure and manipulate the individual nanomaterials and nanostructures in pavement. Characterization of nanomaterials and nanostructures has been largely based on surface analysis technique and conventional characterization methods developed for bulk materials. The most widely used in characterizing nanomaterials and nanostructures in pavement engineering are X-ray diffraction (XRD), various electron microscopy (EM) including scanning electron microscopy (SEM) and Field Emission Scanning Electron Microscopy (FE-SEM) (Cao, G., 2006, Kostoff, R. N., Koytcheff, R. G. and Lau, C. G. Y., 2007).

2.1 X-ray Diffraction (XRD) Analysis

XRD is a very important experiment technique that has long been used to address all issues related to the crystal structure of solids, including lattice constant and geometry, identification of unknown materials, orientation of single crystals, preferred orientation of polycrystals, defects, stresses, etc. In XRD, a collimated beam of X-rays, with a wavelength typically ranging from 0.7 - 2 A, is incident on

a specimen and is diffracted by the crystalline phases in the specimen. This diffraction pattern is used to identify the specimen’s crystalline phases and to measure its structural properties (Cao, G., 2006). XRD is nondestructive and also a powerful technique for investigating of the following (Arkema, 2010):

• Crystallinity • Polymorphism (crystalline phase identification) • Additives, pigments and fillers identification • Active compounds and excipients • Preferred orientation or texture • Residual stress and strain

The XRD analysis method can be applied to materials in powder form, or to manufactured parts, films, plaques, fibers, cured components, coatings, wafers or multilayer systems. Measurements can be made in reflection, transmission and grazing (glancing) angle modes. Temperature experiments allow the study of phase transitions for each crystalline structure present in the material. Analysis of preferred orientation in plastics, coatings, or metals can be studied by pole figure measurements, through texture coefficient measurements, or using camera attachment (Lee, S. L., Windover, D., Doxbeck, M. et al., 2000, Ortiz, A. L. and Shaw, L., 2004, Pattanaik, S., Huffman, G. P., Sahu, S. et al., 2004, Faurie, D., Renault, P. O., Le Bourhis, E. et al., 2006, Zhong, Y., Ping, D., Song, X. et al., 2009, Arkema, 2010).

2.2 Scanning electron microscope (SEM)

SEM is a type of electron microscope that images the sample surface topography composition and other properties by a source of focused electrons into a beam, with a very fine spot size of 5 nm and having energy ranging from a few hundred eV to 50 KeV, which is raster over the surface of the specimen by deflection coils. As the electrons strike and penetrate the surface, a number of interactions occur that result in the emission of electron and photons from sample, and SEM images are produced by collecting the emitted electrons on a cathode ray tube (CRT). The resolution of the SEM approaches a few nanometers, and the instruments can operate at the magnifications that are easily adjusted from ~ 10 to over 300,000 (Joy, D. C., 1997, Cao, G., 2006, Arkema, 2010). The types of signals produced by SEM include secondary electron images, back-scattered electron images and elemental X-ray maps. When a high-energy primary electron interacts with an atom, it undergoes either inelastic scattering with atomic electrons or elastic scattering with the atomic nucleus. Due to the very narrow electron beam, SEM micrographs have a large depth of field yielding a characteristic three-dimensional appearance useful for understanding the surface structure of a sample. This is exemplified by the micrograph of pollen shown to the right.

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A wide range of magnifications is possible, from about 10 times (about equivalent to that of a powerful hand-lens) to more than 500,000 times. Not only does the SEM produce topographical information as optical microscopes do, it also provides the chemical composition information near the surface (Joy, D. C., 1997, Kalaitzidis, S. and Christanis, K., 2003, Lim, S. C., Kim, K. S., Lee, I. B. et al., 2005, Cao, G., 2006, Arkema, 2010).

2.3 Field Emission Scanning Electron Microscopy (FE-SEM)

Field emission (FE) is the emission of electrons from the surface of a conductor caused by a strong electric field. An extremely thin and sharp tungsten needle (tip diameter 10–100 nm) works as a cathode. The FE source reasonably combines with scanning electron microscopes (SEMs) whose development has been supported by advances in secondary electron detector technology. The acceleration voltage between cathode and anode is commonly with magnitude of 0.5 to 30 kV, and the apparatus requires an extreme vacuum (~10–6 Pa) in the column of the microscope. Because the electron beam produced by the FE source is about 1000 times smaller than a standard microscope with a thermal electron gun, the image quality will be markedly improved. The main advantage of the FE-SEM comes from its high resolution and long working length between magnetic lens and sample, which is unobtainable from a state-of-the-art optical microscope (Lim, S. C., Kim, K. S., Lee, I. B. et al., 2005, Bazzana, S., Dumrul, S., Warzywoda, J. et al., 2006, Kimura, H. Y. a. K., 2007, de Souza, W., Campanati, L. and Attias, M., 2008). The FE-SEM images a sample surface by raster scanning over it with a high-energy beam of electrons. The electrons interact with the atoms comprising the sample to produce signals that contain information about surface topography, composition and other properties, such as electrical conductivity. Features can be characterized at length scales from millimeters to around 10 nanometers. Therefore, the FE-SEM is a very useful tool for high resolution surface imaging in the fields of nanomaterials science and its application include (Arkema, 2010):

• Thickness measurement of thin coatings and films • Correlation of surface appearance and surface

morphology • Characterization of size, size distribution, shape

and dispersion of additives, particulates and fibers in composites and blends

• Measurement of height and lateral dimensions of nanometer-sized objects

• Characterization of cell size and size distribution in foam materials

• Elemental analysis of micron-sized features

• Fracture and failure analysis • defect analysis

3.0 TYPES OF NANOPARTICLES USED IN PAVEMENT

At present, nanoparticles are utilized extensively to improve the performance of asphalt pavements by applying different procedures, including modification of asphalt binder in flexible pavement as well as modification of concrete in rigid pavement. Much of the work to date in pavement engineering has been deal with nanoclay and nano-titanium oxide (nano-TiO2) (Jahromi, S. G. and Khodaii, A., 2009, Pacheco-Torgal, F. and Jalali, S., 2010, Sanchez, F. and Sobolev, K., 2010, You, Z., Mills-Beale, J., Foley, J. M. et al., 2010) 3.1 Nanoclay Nanoclays are naturally occurring minerals and subject to natural variability in their constitution. The purity of the clay can affect the final nanocomposite properties. Clay mostly consist of alumina–silicates, which have a layered structure, and consist of silica SiO4 tetrahedron bonded to alumina AlO6 octahedron in a various ways. One of the most frequently used layered silicates is montmorillonite (MMT), which has a 2:1 layered structure with two silica tetrahedron sandwiching an alumina octahedron. The thickness of the MMT layers (platelets) is 1 nm with a large active surface area can have an intensive interaction between bitumen and depends upon the type of material mixed. MMT is also commonly used because it is environmentally friendly, readily available and its structure and chemistry have been well studied.(Ghile, D., 2006, Jahromi, S. G. and Khodaii, A., 2009, Yarahmadi, N., Jakubowicz, I. and Hjertberg, T., 2010, You, Z., Mills-Beale, J., Foley, J. M. et al., 2010). The proper selection of modified clay is essential to ensure effective penetration of the polymer into the interlayer spacing of the clay and so resulting in the desired exfoliated product. An exfoliated morphology occurs when the clay platelets are extensively delaminated and completely separated due to thorough polymer penetration by various dispersion techniques. To achieve fine dispersion, mechanical forces alone are not sufficient; rather, there should be a thermodynamic driving force to separate the layers into the primary silicate sheets. This thermodynamic driving force is being introduced by inserting a certain coating of surfactants (an agent such as detergent, which reduces surface tension) on each individual layer. These surfactant molecules increase the layer distance. They, moreover, improve the compatibility with the polymer and can enhance the bonding of nanoclay because they can be

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mixed with the polymer (Jahromi, S. G. and Khodaii, A., 2009, You, Z., Mills-Beale, J., Foley, J. M. et al., 2010). 3.2 Titanium dioxide (TiO2)

TiO2 has been known as a useful photocatalytic material is attributed to the following characteristics: (a) relatively inexpensive, safe, chemically stable; (b) high photocatalytic activity compared with other metal oxide photocatalysts; (c) compatible with traditional construction materials, such as cement, without changing any original performance; (d) effective under weak solar irradiation in ambient atmospheric environment. The concept of titanium dioxide as a photocatalyst is similar to plant photosynthesis which allows the decomposition of water into oxygen and hydrogen in the presence of Ultra Violet (UV) rays (320–400 nm). Based on this heterogeneous photocatalytic oxidation process, nitrogen oxides are oxidized into water-soluble nitrates while sulfur dioxide is oxidized into water-soluble sulfates; these substances can be washed away by rainfall (Kim, T. K., Lee, M. N., Lee, S. H. et al., 2005, Chen, J. and Poon, C.-s., 2009, Hassan, M. M., Dylla, H., Mohammad, L. N. et al., 2010) The bulk material of TiO2 is well known to have three crystal structures: anatase, rutile and brookite. The anatase type is more widely used because it has a higher photoactivity than the other types of TiO2. Among them, the TiO2 exists mostly as rutile and anatase phases and both phases have tetragonal structures. Rutile is a high-temperature stable phase and has an optical energy band gap of 3.0 eV (415 nm), while anatase is formed at a lower temperature with an optical energy band gap of 3.2 eV (380 nm) as well as refractive index of 2.3. It is well known that generally, the TiO2-based photocatalyst with anatase phase shows more excellent photocatalytic effect than that with rutile phase, and the anatase phase can be transformed into the rutile phase at above 800 oC (Kim, T. K., Lee, M. N., Lee, S. H. et al., 2005). 4.0 APPLICATIONS OF NANOPARTICLES IN

PAVEMENT The most often used of pavement can be divided into two main categories: flexible and rigid. The wearing surface of flexible pavements is usually a mixture of sand, aggregate, a filler material, and bitumen in a controlled process, placed, and compacted. Flexible pavements have low flexural strength and flexible in structural behavior under traffic loads. On the other hand, rigid pavements are normally constructed of Portland cement concrete which consists of Portland cement, coarse aggregate, fine aggregate and water. Rigid pavements have some flexural strength and have a slab action which is capable of transmitting the wheel loads to wider area.

4.1 Applications of nanoclay in flexible pavement Many studies have been conducted and focused on nanoclay modified bitumen. In Netherland, Ghile had performed mechanical tests on asphalt mixture modified by cloisite. The result showed that nanoclay modification improves mechanical behavior properties of mixture such as indirect tensile strength, creep and fatigue resistance (Ghile, D., 2006). In China, Yu et al. have used different contents of montmorillonite (MMT) and organomodified montmorillonite (OMMT) in modified bitumen. Results showed that the softening point and viscosity of the modified bitumen were increased at high temperatures. Furthermore, the modified bitumen exhibited higher complex modulus and had lower phase angle. They also claimed that the MMT and OMMT modified bitumen enhanced viscoelastic properties, which improve its resistance to rutting at high temperatures (Yu, J., Zeng, X., Wu, S. et al., 2007). Also, in a recent work, Yu et al. had investigated the effect of OMMT on thermo-oxidative and UV aging properties of asphalt. They showed that the MMT and OMMT modified asphalts have higher rutting resistance and very good storage stability (Yu, J.-Y., Feng, P.-C., Zhang, H.-L. et al., 2009). The effect of nanoclay (nanofil-15 and cloisite-15A) on rheological properties of bitumen have been studied by Jahromi, S. G., & Khodaii, A. Tests performed on bitumen samples proved that the nanoclay modifications help to increase the stiffness and ageing resistances (Jahromi, S. G. and Khodaii, A., 2009). On the other research, Jahromi, S. G., Andalibizade, B., and Vossough, S. had conducted a rheological tests on binders and mechanical tests on asphalt mixture. They also used the same types of nanoclay. Test results showed that nanoclay can improve properties such as stability, resilient modulus, and indirect tensile strength, and result in superior performance under dynamic creep. However, they stated that nanoclays did not have a beneficial effect on fatigue behavior in low temperature. Optimum binder content and void in total mixture (VTM) increase by adding nanoclay to bitumen (Jahromi, S. G., Andalibizade, B., & Vossough, S, 2010). In other research, the effect of styrene–butadiene–rubber/montmorillonite (SBR/MMT) modification on the characteristics and properties of asphalt were investigated by Zhang et al. Results showed that the addition of SBR/MMT increased both the softening point and viscosity and decreased the penetration of the modified asphalts at high temperatures. They also stated that modified asphalts exhibited higher complex modulus (G*) and lower damping factor (tan δ). It implies that SBR/MMT displays improved viscoelastic properties, resulting in enhancing its resistance to rutting at high temperature (Zhang, B., Xi, M., Zhang, D. et al., 2009). Meanwhile, Galooyak et al had studied the effect of styrene–butadiene–styrene/ organomodified

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montmorillonite (SBS/OMMT) modified bitumen mixtures. Results showed that the presence of nanoclay improves the storage stability of PMB significantly without adverse effect on other properties of it. (Galooyak, S. S., Dabir, B., Nazarbeygi, A. E. et al., 2010). You et al. described that nanoclay improved the G*, viscosity and has better low-temperature cracking resistance (You, Z., Mills-Beale, J., Foley, J. M. et al., 2010). Besides that, Zare-Shahabadi, A., Shokuhfar, A. & Ebrahimi-Nejad, S. had studied the used of bentonite clay (BT) and organically modified bentonite (OBT) to reinforce and modify a bituminous paving asphalt binder. They found that the modified asphalts have higher rutting resistance when tested by dynamic shear rheological. It was found also indicated that adding of BT and OBT can significantly improve low temperature rheological properties and cracking of asphalt (Zare-Shahabadi, A., Shokuhfar, A. and Ebrahimi-Nejad, S., 2010). 4.2 Applications of TiO2 in rigid pavement

In China, the abrasion resistance and the flexural fatigue performance of concrete containing nano-TiO2 as additives for pavement is experimentally studied by Li et al. The test results indicated that the abrasion resistance of modified concrete pavement was increased with increasing compressive strength and also improved the fatigue performance. The sensitivity of their fatigue lives to the change of stress is also increased. Besides that, the addition of nano-TiO2 also refines the pore structure of concrete and enhances the resistance to chloride penetration on concrete (Li, H., Zhang, M.-h. and Ou, J.-p., 2006, Li, H., Zhang, M.-h. and Ou, J.-p., 2007, Zhang, M.-h. and Li, H., 2010). In other research, Hassan et al. investigated the used of TiO2 particles as coating for concrete pavement where these particles can trap and decompose organic and inorganic air pollutants by a photocatalytic process. They stated that the wearing of the samples with 3% TiO2 slightly improved the nitrogen oxides, NOx (NO+NO2) removal efficiency. They also claimed that the use of TiO2 coating as a photocatalytic compound would provide acceptable durability and wear resistance (Hassan, M. M., Dylla, H., Mohammad, L. N. et al., 2010). In Tokyo, Fujishima et al. had coated several road areas with cement mixtures containing TiO2 colloidal solutions (Fig. 12). The results obtained in an area of 300 m2 showed 50–60 mg/day NOx degradation (Fujishima, A., Zhang, X. and Tryk, D. A., 2008). Chen and Liu had reported the potential of heterogeneous photocatalysis as an advanced oxidation technology for NOX removal from vehicle emissions by using TiO2 as a photocatalyst immobilized on the surface of asphalt road. Based on asphalt road material porous characteristic, they utilized permeability technology to make asphalt nano-TiO2

to be environmental protection materials. Results of experiment revealed that decontaminating rate of the productions ranged from 6% to 12% and this kind of photochemical catalysis environmental protection material has good environment purification function (Chen, M. and Liu, Y., 2010). 5.0 CONCLUSION Nanotechnology has the potential for improvements in the field of pavement material and construction in future. In flexible pavement, researchers are focused on the modification of binder using nanoclay and with that modified binder they evaluated the performance of the mixtures. The engineering properties of modified binders and mixtures are significantly improved, particularly in the areas of stiffness, storage stability, rutting resistance, low-temperature cracking resistance and ageing resistances. On the other hand, the abrasion resistance and the flexural fatigue performance of concrete containing nano-TiO2 as additives for pavement is increased with increasing compressive strength and also improved the fatigue performance. The sensitivity of their fatigue lives to the change of stress is also increased. Besides that, the use of TiO2 photocatalyst in combination with rigid pavement had shown an improved on NOx removal efficiency. The used of TiO2 coating as a photocatalytic compound would also provide acceptable durability and wear resistance. With the advances in instrumentation and computational science, it is believed that nanotechnology will exploit the improvement of pavement material properties and construction process in future.

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1

VERTICAL DISPLACEMENT OF UNDERSIDE SHAPED CONCRETE BLOCK PAVEMENT Azman Mohamed1

Researcher az_man@ic.utm.my Hasanan Md Nor2

Professor hasanan@utm.my Mohd Rosli Hainin2

Associate Professor mrosli@utm.my 1Department of Civil Engineering, Razak School of Engineering and Advanced Technology, Universiti Teknologi Malaysia, International Campus, Jalan Semarak, 54100 Kuala Lumpur, Malaysia. 2Department of Geotechnics and Transportation, Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81300 Skudai, Malaysia. ABSTRACT: A new shaped block concept for Concrete Block Pavement (CBP) by introducing Underside Shaped Concrete Block (USCB) to the road surface layer has the potential to enhance the road construction development in Malaysia. The USCB concept utilizes the groove patterns to grip and produce resistance to the underside surface of block units onto the sand bedding layer. This concept is in the early stage of laboratory study to build up the understanding of its behavior to produce better pavement performance. The USCBs were manufactured in the laboratory with three different rectangular groove depths. An average USCBs compressive strength of 25 MPa was produced. The compaction capability and settlement of the bedding sand and vertical displacement USCBs were studied in the pavement model. Push in test was performed to determine the resistance to vertical displacement of USCBs. Groove depth, groove size, underside surface area and volume of USCB have significant influence on the vertical displacement of USCB pavement. Keyword: Concrete Block Pavement; Underside Shaped Concrete Block; Groove; Vertical Displacement; Settlement; Push In

1. INTRODUCTION

Concrete Block Pavement (CBP) differs from other forms of pavement in that the wearing surface is made from small paving units bedded and jointed in sand rather than continuous paving. According to Panda and Ghosh (2001), beneath the bedding sand, the substructure is similar to that of a conventional flexible pavement. Sudip L. Adhikari 2008 mentioned that blocks are a major load-spreading component which is comprised of concrete blocks bedded and jointed in sand. Interlock has been defined as the inability of an individual bock to move independently of its neighbours and has been categorized as having three components: horizontal, rotational, vertical. Interlock is of major importance for the prevention of movement of pavers horizontally when trafficked Various block parameters contribute to the structural capacity of pavement. This study discusses laboratory results relating the effect of changing groove depth, groove size, area of underside surface and volume of block to provide the basic understanding of the groove effects. Generally, Underside Shaped Concrete Block (USCB) has

lighter weight and has more underside surface contact area than normal concrete block. 2. BACKGROUND In CBP the load spreading capacity of concrete blocks layer depends on the interaction of individual blocks with jointing sand to build up resistance against applied load. The shape, size, thickness, laying patterns, etc are importance block parameters, these influence the overall performance of the pavement. The shape of the block influences the performance of the block pavement under load. It is postulated that the effectiveness of load transfers depends on the vertical surface area of the block (Panda and Ghosh, 2001). Many guidelines have been produced to provide sufficient concrete block’s strength, thickness and interlocking defined as the inability of an individual block to move independently or its neighbors. Concrete blocks have their own weight, thickness, strength and shape to ensure the mechanism will establish high performance. Concrete block can sustain the load of vehicles, so it is used as the material to construct pavement.

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The laying course thickness differs from country to country. Most countries require a 50 mm compacted thickness. However, Australia has specified a compacted thickness of 20 mm to 25 mm. This is a very thin layer and will therefore require the surface of the underlaying base to be very smooth (Beaty, 1992). Adequate compaction is required to minimize the settlement of CBP. The laying course material and blocks should be compacted using a vibrating plate compactor. Some blocks may require a rubber or neoprene faced sole plate to prevent damage to the block surfaces (Interpave, 2004). The block paved area should be fully compacted as soon as possible after the full blocks and cut blocks have been laid, to achieve finished pavement tolerances from the design level of ± 10 mm under a 3 m straightedge (ICPI, 2004). Normally two cycles of compaction are applied. The first cycle compacts the bedding sand and cause this material to rise up the joints and the second cycle is applied once joint sand is brushed into the joints. Panda and Ghosh (2002), reported that the strength and laying pattern of blocks has no influence on the vertical displacement of the block pavement. However, the vertical displacement is highly influenced by block thickness. Thus, block thickness of 80 mm is sufficient for heavily trafficked roads.

3. MATERIALS AND EXPERIMENTAL

WORKS 3.1 Materials The USCBs were manufactured in the laboratory. These were made using ordinary Portland cement comply with MS 522 Part 1. The natural aggregates used include natural river sand as the fine aggregate and crushed granite with normal size less than 10 mm as the coarse aggregate. The fine and coarse aggregate complied with the requirements of ASTM

C136-06 and CCAA (TN 56). The blocks were cured by covered with wet gunnysacks for 28 days. Concrete blocks (Fig. 2) were tested to ensure concrete mix satisfies the specification. The blocks were tested at the age of 28 days with average compressive strength meeting the minimum requirement of 25 MPa as suggested by Shackel, 1990. The length, width and thickness of rectangular concrete blocks is 200 mm, 100 mm and 80 mm respectively with the length to width ratio is 2 for this study (BS 6717-1, 1993). Parameter studied in this research were groove size, groove surface area and block volume. The details of block shapes studied are given in Fig. 1 and geometrical details are given in Table 1.

Fig. 1. Details of blocks shapes used in this study

Fig. 2. USCB –R(30/25)

3.2 Test Setup The tests of USCB were carried out in a rigid steel box of 1000 mm x 1000 mm square in plan. The grid measurement points are as shown in Fig. 3. The points were marked on the steel box frame. A reaction steel frame was used to apply static load on the 12 mm thick steel plate, hydraulic jack and load cell of 200 kN capacity as shown in Fig. 4.

Table 1. Details of blocks used in study

Block typeWidth, B

(mm)

Length, L

(mm)No of

'L'

Height, h

(mm)No of

Groove

Distance Between Groove, d (mm)

No of 'd'

Edge Length, e (mm)

No of 'e'

Underside Shaped Area,

A (cm2)

A% of Different Compare

to NB MultiplicationVolume, V (cm3)

V% of Different

Compare to NB

NB 200 0 1 1600 0USCB - R(30/15) 100 30 3 15 3 30 2 25 2 290 45 1.45 1465 8.44USCB - R(30/25) 100 30 3 25 3 30 2 25 2 350 75 1.75 1375 14.06USCB - R(30/35) 100 30 3 35 3 30 2 25 2 410 105 2.05 1285 19.69

∗ NB – Normal

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Fig. .3. Testing layout pelan 3.3 Construction of Test Sections The test sections of USCB were constructed within the steel box. The base of steel box is covered with hard neoprene of a 3 mm thick which simulate the subgrade layer. Over the hard neoprene, a plastic sheet is used to cover it in order to avoid contaminating the hard neoprene with bedding sand. The bedding sand ( 4 % - 8 % moisture content) was spread in a uniform layer to give a depth of 70 mm. This value was selected to achieve an average of 50 mm thick of bedding sand after two cycles of compaction process. Over the bedding sand, the USCBs of 80 mm thick were laid in a basket weave pattern. The joint width and quality of sand in bedding and joints were kept constant for all the experiments as according to CCAA, TN 56. The whole USCBs were compacted by plate vibrator until the compaction was completed. Finally, the measurement points were marked on the USCB block units as shown in Fig. 3. 3.4 Test Procedures The measurements were made on bedding sand to obtain the desired thickness and the level of USCBs before and after compaction throughout the measurement points. These measurements were taken to measure the settlement of bedding sand and USCBs. A hydraulic jack fitted to the reaction frame was used to apply a central load to the entire USCB units as shown in Fig. 3, through a rigid rectangular steel plate. This arrangement is call push in test. The load was increased uniformly up to 25 kN. While the loads were increased, the vertical displacement were measured to an accuracy 0.01 mm using two Low Voltage Displacement Transducer (LVDT) connected to a data logger. The LVDTs were placed

on two opposite sides of the loading plate at equal distance from the centre. The average value of the two settlement readings was tabulated and drawn in Fig. 5.

Fig. .4. Pavement model setup 4. RESULTS AND DISCUSSIONS 4.1 Effects of USCBs on bedding sand The types of USCBs namely USCB-R(30/15), USCB-R(30/25) and USCB-R(30/35) are referred to the groove depths of 15 mm, 25 mm and 35 mm respectively (Fig. 1 and Table 1). Figure 5 shows the vertical displacement of USCBs on bedding sand of the three types of USCBs and control blocks at different grid numbers after compaction. Previous study has also shown that settlement for normal block is the range between 15mm to 20 mm. From this study, the vertical displacement of USCB-R(30/15), USCB-R(30/25) and USCB-R(30/35) were 18 mm, 15 mm and 20 mm respectively. For USCB-R(30/15) the bedding sand has fully filled the 15 mm groove depth. On the other hand, the of USCB-R(30/25) and USCB-R(30/35) the bedding sand did not fully fill into the 25 mm and 35 mm grooves. This situation is proven by push in test result as shown in Fig. 6. It shows the effect of loading to the vertical displacement for different types of USCBs at different location referring to the single block (block No 24) and double blocks (block No 21 & 22 and No 27 & 28). It was observed that the vertical displacement of blocks increased in nonlinear manner with increasing loads. From Fig. 5, bedding sand has been able to full fill the groove of USCB-R(30/15) compared to other types at tested location of block’s number. Additionally, for every type of USCBs were observed to have almost uniform vertical displacement at it selected position. From this study the block type of USCB-R(30/15) has shown lower vertical displacement at blocks location

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(No.21 & No. 22), (No. 24), and (No.27 & No.28) compared to other USCBs control blocks .

Fig. 5. The vertical displacement of USCBs and height of sand filled into groove

Fig. 6. Comparisons of USCBs vertical displacement under push in test 4.2 Effects of groove depth to the USCB Fig. 7 shows areas and volumes of USCBs versus displacements due to the applied vertical loads. The relationship between vertical displacement and area and volume of USCBs is moderate considering the R2 value of 0.568. The above relationship can be studied for others groove pattern in the future. This value of R2 also can be used by comparing between other underside surface patterns of groove in the future.

5

(a)

(b)

This study is a one of the preliminary ways to have in the selection of suitable groove depth for USCBs. Besides that, further study is needed to investigate the compatibility between various patterns of grooves for USCBs pavement. One other way to recognize their compatibility is through simulation study using finite elements method.

Fig. 7. The displacement relationship 5. CONCLUSIONS The main conclusions that can be drawn from this study are as follow: 1. The block type USCB-R (30/15) is the best

among the tested block because it has lower vertical displacement as the grooves were fully filled with bedding sand.

2. The superiority of block type USCB-R (30/15) is consistence when tested either in the middle or at the edge of the pavement.

3. Groove area and groove volume of blocks are moderately related to vertical displacement.

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aspects of interlocking concrete block Pavements. Proceedings of the 45th Canadian Geotechnical Conference, pp. 41-1/41-7.

Cement And Concrete Association Of Australia (1986). A Specification for Construction of Interlocking Concrete Road Pavement. (TN56).

Concrete Masonry Association Of Australia (1986).

Specification for Concrete Segmental Paving Units (MA 20).

Hata, M., Iijima, T. and Yaginuma, H. (2003).

Report On The Survey And Repair of Interlocking Blocks Used For Ten Years At Heavy-Traffic Bus Terminal. Proceeding 7th International Conference on Concrete Block Paving. South Africa.

ICPI (2004). Mechanical Installation of Interlocking

Concrete Pavements. Tech Spec 11, Interlocking Concrete Pavement Institute, Washington, DC, U.S.A.

Panda, B. C. and Ghosh, A. K. (2001). Structural

behavior of concrete block paving. I: Sand in bed and joints. Journal of Transportation Engineering, 128(2), 123–129.

Panda, B. C. and Ghosh, A. K. (2002). Structural

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Shackel, B (1990). Design and Construction of

Interlocking Concrete Block Pavement. London and New York; Elsevier.

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Sudip L. Adhikari. (2008). Structural Performance

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(2005). Structural Behavior of Cast in Situ Concrete Block Pavement. Journal of Transportation Engineering, Vol. 131, No. 9:662.