effect of varying mixing & compaction temperature on marshall properties of bituminous concrete...

Effect of varying Mixing & Compacting Temperature On Marshall properties

VISVESVARAYA TECHNOLOGICAL UNIVERSITY

Belgaum-590 014

SEMINAR REPORT On

“EFFECT OF VARYING MIXING & COMPACTION

TEMPERATURE ON MARSHALL PROPERTIES OF

BITUMINOUS CONCRETE MIX”

Submitted in partial fulfillment of the requirements for the award of

M.TechIn

HIGHWAY TECHNOLOGYBy

SHIVA KUMAR.M.J

Under the Guidance

Of

Dr. KrishnamurthyProfessor – PG Studies,

RASTA – Center for Road Technology,

Bangalore.

RASTA – Center for Road TechnologyVTU – Extension Center

VOLVO Construction Equipment Company Bangalore – 560 058

RASTA-Centre for Road technology -1-


RASTA – Center for Road TechnologyVTU – Extension Center

VOLVO Construction Equipment, Road Machinery Campus

Bangalore – 560 058.

CERTIFICATE

Certified that the Seminar work entitled “EFFECT OF VARYING

MIXING & COMPACTION TEMPERTURE ON MARSHALL

PROPERTIES OF BITUMINOUS CONCRETE MIX” is a bonafied work

carried out by, Mr. SHIVA KUMAR M J , University Seat Number

1IR09CHT12 in partial fulfillment for the award of M.Tech degree in

Highway Technology of the Visvesvaraya Technological University,

Belgaum during the year 2009-2010. It is certified that all

corrections/suggestions indicated for Internal Assessment have been

incorporated in the report. The Seminar report has been approved as it

satisfies the academic requirements in respect of Seminar work prescribed

for the said Degree.

Signature of Guide Signature of Professor – PG Studies

(Dr. Krishnamurthy) (Dr. Krishnamurthy)



ACKNOWLEDGEMENT

The satisfaction that accompanies the successful completion of any task would be

incomplete without mentioning of the people who made it possible. Many responsible for

the knowledge and experience gained during the work course

I express my heartfelt gratitude to the entire teaching faculty who relentlessly tried

to get the best out of me. It is because of their great efforts and encouragement that I am

here on the verge of becoming a Post Graduate ready to take up the challenges that come

in my professional life.

I would like to express my sincere gratitude to Prof. B.R.Srinivas murthy,

honorable Chief Co-coordinator PG Certificate course in Road Technology for his

excellent guidance and kind co-operation throughout.

I am very thankful to Prof. Krishnamurthy for his excellent teaching, his

correlation of knowledge and practical approach, which gives me an idea to solve

complicated things effectively.

I am very much thankful to Mr. K.S.Aithal , Mr. Anjaneyappa and Mrs.G.

Kavitha, Faculty members of Rasta Road Institute for their valuable and inspiring

guidance at every stage and their accessibility which made me to understand the subject

to its fullest depth and its usage.

I am thankful to all my classmates, friends and non-teaching staff of RASTA,

Centre for Road Technology for their co-operation.

Last but not the least, I wish to thank M/S VOLVO Construction Equipment

Company., Bangalore who have pioneered the course to RASTA, Centre for Road

Technology.



SYNOPSIS

A pavement is a structure constructed with an objective of providing safe, durable and

good riding surface over a desirable period with minimum maintenance. This obviously

makes the pavement to meet certain functional and structural requirements during its

lifetime. The ability to characterize asphalt pavement materials in terms of fundamental

properties is becoming increasingly more important.

The need for accurate, consistent volumetric measurements of hot mix asphalt (HMA) has

become increasingly important in the past few years. This change has come about because

more and more states are utilizing volumetric measurement to design the HMA mixtures

and then to evaluate them during construction. Since volumetric measurements are now

widely used for quality assurance, it has become a major concern for both the state and

the contractor to measure these properties with accuracy and reliability. Minor changes in

volumetric properties may be the difference in whether a contractor receives full pay or

reduced pay for produced mixtures. It is believed that differences in how mixtures are

handled and tested have played role in discrepancies between government agency and

contractor test results.

Hot mix asphalt (HMA) mixture compacted at different temperature has always been a

concern to researcher. Compaction below the standard compaction temperature may bring

reverse effect on HMA properties. The objective of this study was to evaluate the effects

of compaction temperatures and mixing temperatures in Marshall Properties for a

bituminous concrete mix.



CONTENTS

Page no

1. INTRODUCTION

1.1. General 1

1.2. Objective of the study 2

1.3. Scope of the project 2

2. LITERATURE REVIEW

2.1. Effect of Compaction Temperature 4

2.2. Effect of Mixing Temperature 4

2.3. History of research 5

3. PRESENT INVESTIGATIONS

3.1. Main Constituents of BC grade-2 7

3.2. Gradation of Aggregates 7

3.3. Preliminary Laboratory investigation 8

3.4. Design of Bituminous Concrete mixes 9

3.4.1. Marshall Stability Test 9

3.5. Mixing & Compacting Temperature for the mix 10

4. TEST RESULTS AND OBSERVATIONS

4.1. Aggregates 11

4.2. Bitumen 12

4.3. Marshall Properties for B.C mix 13

4.4. Effect of varying Mixing & Compacting Temperature on Marshall 17

Properties

5. DISCUSSIONS AND CONCLUSIONS 22

6. REFERENCES 25



List of Tables

Table 3.1 Gradation of aggregates as per MoRT&H Specification for BC mix 8

Table 3.2 Mixing temperature and Compaction temperature for different grade 10

of bitumen

Table 4.1 Results of Tests on physical properties of Aggregates & fillers 11

Table 4.2 Results of Tests on physical properties of 60/70grade bitumen 12

Table 4.3 Marshall Test results for 60/70 grade bitumen 13

Table 4.4: Marshall Values at OBC for mid limit Gradations of BC using 60/70

Grade bitumen 16

Table 4.5: Marshall Properties by keeping Constant Mixing Temperature of

130°C and by varying Compaction temperature for Bituminous

Concrete Mix 18


157.5°C and by varying Compaction temperature for Bituminous

Concrete Mix 19


180°C and by varying Compaction temperature for Bituminous

Concrete Mix 20

List of Graphs

Graph 4.1-5: Graphs of BC mixes using 60/70 grade bitumen to determine OBC 13

Graph 4.6: Effect of Mixing and compaction temperature to the Bulk specific 21

Gravity of the BC mix



Graph 4.7: Effect of Mixing and compaction temperature to the Marshall stability 21

Of the BC mix

CHAPTER 1

INTRODUCTION

1.1 General

The design of bituminous mixture by Marshall Method involves the proportioning

of the aggregates and bitumen to produce a mix that will have the optimum qualities and

properties. The purpose is to develop a design, by trial means, which will contain

optimum amount of bitumen, having adequate voids, satisfactory flow properties and

possess a planned combination of stability, durability and flexibility, based on the

climatic condition, traffic density and loads it is intended to carry.

Premix is one type of Hot mix asphalt (HMA) widely used in road construction

worldwide. It is considered by many highway engineers as premier paving product

available anywhere at any cost and the most popular as paving material with high skid

resistance, high comfort ability and low maintenance cost. HMA paving consist of a

combination of aggregate uniformly mixed and coated with asphalt cement. Term of "hot

mix" comes from aggregate and bitumen dried and heated for proper mixing and

workability and mix together with desired temperature.

The aggregate and asphalt will be combined in an asphalt mixing plant in which it

will be proportioned, heated, and mixed to produce the desired paving mixture. After the

plant mixing is complete, the mix will be transported to site and spread with paving

machine in loosely compacted layer to uniform , smooth surface. Then the mix will be

compacted by heavy roller to produce smooth and well consolidated course.

Compaction is one of major issue in HMA and important criteria in process to

produce good quality of hot mix asphalt. Temperature controls asphalt cement viscosity

which affect its ability to coat and provide adequate lubrication for aggregates and slides

with each other and pack into dense mass during compaction.

There are various instances where surface layer has failed due to carelessness in

maintaining proper temperature during mixing and compaction.

Good physical Properties of bituminous mixtures can be achieved by proper

selection of ingredients of the mixture. Even after the proper selection of materials,

specifications and proper mix design, the properties of bituminous mixes are governed by

other factors also. These factors include time and temperature of heating, Mixing, type of



compaction etc. (1)

1.2 Objectives of present study

The main objectives of present studies are:

The objective of this project is to study the effect of varying mixing and compacting

temperatures on Marshall Properties of bituminous mix(Bituminous concrete-II).

Marshall Moulds were prepared and each specimen tested for the following:

Bulk Specific Gravity, (Gb )

Air Voids, (VV )

Voids in Mineral Aggregate, (VMA)

Voids Filled with Bitumen, (VFB)

Marshall Stability and

Flow

1.3 Scope of the project:

Temperature is a very important parameter for the bituminous mixes, during

mixing and also during compaction in the field. Sometimes, the controlling of

temperatures becomes very difficult to maintain in the field within the specified

conditions. This will make the laid pavement to deteriorate rapidly. Variation in

temperatures causes large scale deviation in Marshall Properties.

In the present work, an effort has been done to study the effect of both mixing and

compacting temperatures on bituminous concrete mix. The temperatures during both

mixing and compaction have been varied from the standard specification (as specified by

MoRT&H) and the Marshall properties have been compared for different temperatures.



CHAPTER 2

LITERATURE REVIEW

Flexible pavements with bituminous surfacing are widely used in India. The high

traffic intensity in terms of commercial vehicles, over loading of trucks and significant

variations in daily and seasonal temperature of the pavement have been responsible for

early development of distress symptoms like raveling undulations, rutting, cracking,

bleeding, shoving and pot holing of bituminous surfacing. A factor, which causes further

concern in India, is very high and very low pavement temperatures in some parts of the

country. Under these conditions, flexible pavements tend to become soft in summer and

brittle in winter.

During winter, bitumen contracts due low temperature, since the pavements are

constrained, they cannot contract, hence the thermal stresses starts building up. If the

temperature falls below the critical temperature Tcr, the stresses exceed the strength of the

binder and pavement cracks. Due to the length to width ratio of roads, transverse cracks

appear first, which are followed by longitudinal cracks. This process results in a

phenomenon referred to as block cracking. The cracking due to temperature is not severe

in southern India but can occur in northern India. Subsequently at higher temperature the

mix looses its strength.

There are various instances where surface layer has failed due to carelessness in

maintaining proper temperature during mixing and compaction. Bitumen is a thermo

plastic material. It means that the consistency of the material changes with change in

temperature. Bitumen softens whenever it is heated and becomes more viscous (i.e. high

resistance to flow) when cooled... Consistency of bitumen binders generally accepted in

India is based on standard tests namely, penetration, ductility and softening point. The

physical properties of bitumen mixtures are very much influenced by the rheological

properties of the binder. The requirement of bituminous mixtures is to have high

compressive strength to resist the deformation caused by the traffic load. It is also

desirable for the mixture to have an adequate tensile strength to resist wheel friction and

tension caused by contraction. The bituminous surface should also have certain elastic

property to prevent developments of cracks due to deformation. In addition to have

sufficient stability to prevent crushing, the bituminous pavements should be sufficiently

dense to make it water proof and durable to preserve these qualities. The above properties

of bituminous mixtures can be achieved by proper selection of ingredients of the mixture.



Even after the proper selection of materials, specifications and proper mix design, the

properties of bituminous mixes are governed by other factors also. These factors include

time and temperature of heating, Mixing, type of compaction, curing etc.

Temperature is an important factor in bitumen pavement construction. The effects

of temperature must be viewed from several standpoints:

1. Its effect on the mix constituents which changes the viscosity and some of the

properties of the aggregate which affect both the spreading and absorption of the

bitumen.

2. Its effect on the mixing, laying and compaction operations as a result of these

changes in the properties of the mix constituents.

3. Surface layer has failed due to carelessness in maintaining proper temperature

during mixing and compaction.

2.1. Effect of mixing Temperature

In hot mix asphalt paving mixture, bitumen and aggregate are blended together in precise

proportion. The relative proportion of these materials in mixing will determine the

physical properties of the mix and how the mix will perform when finishes as asphalt

pavement.

However, there is a trend nowadays to operate asphalt plant at lower mixing

temperature. Mixing at lower temperature result primarily for one major reason to

conserve energy required producing the mixture. Lower mixing temperature means lower

operating cost. These lower temperatures commonly result in the introduction of drum

mixer that requires less energy for the production of asphalt mixtures.

2.2. Effect of Compaction Temperature

The effect of compaction temperature is evaluated during quality control/quality

assurance testing. Inaccurate control of compaction temperature could very well occur. It

has always been assumed that the compacted density of HMA is very dependent upon the

temperature. Studies have shown that, the percentage of air voids achieved by the

Marshall hammer decreased from approximately 10.3 to 7.1 when increasing the

compaction temperature from 80 to 160°C. Therefore, the compaction temperature of the

prepared mixes was varied to determine whether or not poor control would significantly

increase the variability of volumetric properties.

The effects of compaction temperature can be subdivided with respect to density and

engineering properties. In procedure of pavement construction the compaction is done

when temperature reach 110°C and in laboratory HMA normally compacted when



temperature reach 145 °C. (2)

2.3. History of research

Hadley (1970) et al has conducted an extensive laboratory study to find the effect

of seven factors on the tensile properties of asphalt material. The result of the studies

showed that compaction temperature along with asphalt content, grade of asphalt, and

aggregate gradation has significant cause to tensile strength. In this study also the entire

result was affected by the compaction temperature and produced strong interaction with

other variables.

Hadley (1978) conducted second laboratory test and founded that reclaiming agent

and compaction temperature has certain effect to the significant increase in tensile

strength, static and resilient modulus of elasticity. However, as the amount of reclaiming

agent increase, the effect of compaction temperature was more important. The viscosity

effect seems to be minimal since all samples were heated and mixed at the same

temperature of 135 °C. This experiment was conducted using recycled asphalt mixtures.

Kennedy et al (1979) also conducted test to determine the effects of increasing

compactive effort at low temperature on tensile strength and static modulus. The sample

used for the study compacted at three different temperatures, 79°C, 93°C and 116°C.

Kennedy using two different compaction method that are methods used by Texas State

Department of Highway and Public Transport (SDHPT) using a gyratory cycles and

modified procedure involving a constant number of gyratory cycles.

Result from the study shows that standard compaction procedure produced higher

tensile strength and static modulus regardless of compaction temperature. However, the

static modulus was less sensitive to compactive effort than tensile strength

As in the previous study effect of differential hardening at the various compaction

temperature does not exist since all sample were heated to the same temperature and

allowed to cool to the desired compaction temperature.

Therefore, the effect of density should not be significant since all samples had

similar values.

In addition to the two previous studies, McBee at al (1978) has observed density

effect in laboratory with asphalt pavement recycled with sulfur. The Marshall stability

samples were compacted at the temperature varies at 88°C to 149°C and the relatively

hard brittle nature of the mixture is evidence by the rather high Marshall stability values

reported.



Many methods are used in attempt to relate the field condition which varies from

direct compaction, with or without rolling, to hand tamping, impact hammer, kneading

action, gyratory shear, vibration, and simulated rolling. The size of the sample must be

determined, not only with respect to maximum aggregate size, but also with respect to the

rationality of the strength test. (1)



CHAPTER 3

PRESENT INVESTIGATIONS

In the present study, the mix type chosen is bituminous concrete grade-2. The mix

design is done based on Marshall Method to meet the requirements as specified in

MoRT&H (IV revision) Specification.

3.1.Main constituents of Bituminous concrete grade-2

Mixture stiffness can be varied by the temperature, speed of loading, level of

compaction and type of bitumen.

Coarse aggregates: Offer compressive and shear strength and shows good

interlocking properties. Material retained on 2.36mm IS sieve is taken as Coarse

aggregates.

Fine aggregates: Fills the voids in the coarse aggregate and stiffens the binder.

Material passing 2.36mm IS sieve and retained on 0.075mm or 75 micron IS sieve

is taken as Fine aggregates.

Filler: Fills the voids between the fine aggregates, stiffens the binder and offers

permeability. Material should pass through 0.075mm or 75 micron IS sieve is

taken as filler. Filler may be stone dust, cement, fly ash & lime.

Binder: Fills the voids, cause particle adhesion.(5)

3.2. Gradation of Aggregates

The aggregate gradation for bituminous concrete mix Grading-2 mid limit gradation

was chosen as per Table-500-18, of MoRT&H (IV revision) specifications.



TABLE 3.1: GRADATION OF AGGREGATES AS PER MoRT&H

SPECIFICATION

Grading 2

Nominal aggregate size 13mm

Layer thickness 30-45mm

I.S sieve(mm) Cumulative % by weight

of

total aggregate passing

Mid limit

19

13.2

9.5

4.75

2.36

1.18

0.6

0.3

0.15

0.075

100

79-100

70-88

53-71

42-58

34-48

26-38

18-28

12-20

4-10

100

89.5

79

62

50

41

32

23

16

7

Bitumen content by mass of total mix

Bitumen Grade (penetration)

5.0-7.0

65

3.3. Preliminary laboratory investigation

In order to assess the quantitative and qualitative improvement in Marshall Stability,

following laboratory investigation are carried out:

1) Basic tests on 60/70 grade bitumen are carried out viz., penetration test, softening

point, ductility test and specific gravity test.

2) Basic tests of aggregates are carried out viz., aggregate impact value

test, crushing strength test, Los Angles Abrasion test and specific gravity of

aggregates.

3) Marshall Stability test on Bituminous concrete with 60/70 grade

bitumen to determine optimum bitumen contents.

4) To determine Marshall Properties for varying mixing and compacting



temperature.

3.4. Design of Bituminous Concrete Mixes

The main objective of the mix design is to produce a bituminous mix by

proportioning various components so as to have:

1. Sufficient bitumen to ensure a durable pavement.

2. Sufficient strength to resist shear deformation under traffic at higher temperature.

3. Sufficient air voids in the compacted bitumen to allow for additional compaction

by traffic.

4. Sufficient workability to permit easy placement without segregation.

5. Sufficient flexibility to avoid premature cracking due to repeated bending by

traffic.

6. Not very high stiffness at low temperature to prevent shrinkage cracks.

The bituminous mix was designed by using Marshall Method of mix design. The

Marshall test is used to obtain the optimum bitumen content based on ASTM D-1559-96

the procedure of testing is given below.

3.5. Marshall Stability Test

The Marshall Stability test is applicable to hot bituminous mix design using

bitumen and aggregates with maximum size of 25 mm.

In this method, the resistance to plastic deformation of cylindrical specimen of

bituminous mixture is measured when the same is loaded. This test procedure is used in

designing and evaluating bituminous paving mixes. The test procedure is extensively used

in routine test programmed for paving jobs.

There are two major features of the Marshall method of designing mixes namely,

i) Density voids analysis.

ii) Stability flow tests.

The Marshall stability of the mix is defined as maximum load carried by a compacted

specimen at a standard test temperature at 60°C. The flow value is the deformation the

Marshall Test specimen undergoes during the loading up to the maximum load in 0.25

mm units.

Marshall Test specimens were prepared by adding 4.5, 5.0, 5.5 and 6.0% of bitumen. The

compacted specimens were removed from the mould after 24 hours. The specimens were

kept in thermostatically controlled water bath maintained at 60°C for 30 minutes. Graphs



are plotted taking bitumen content (%) on x-axis and Marshall stability value, flow value,

bulk density, percentage air voids in total mix, percentage of mineral aggregate and

percentage of voids filled with bitumen on y-axis. The optimum binder content for the

mix is found by taking the average of following three bitumen content found from the

graphs of the results.

1. Bitumen content corresponding to maximum stability.

2. Bitumen content corresponding to maximum unit weight.

3. Bitumen content corresponding to maximum 4% air voids.(3)(4)

3.6. Mixing & Compacting Temperature for the mix:-

Pre mixed bituminous materials, including BM, DBM, SDBC & BC shall be prepared in

hot mix plant of adequate capacity and capable of yielding a mix of proper and uniform

quality with thoroughly coated aggregates.

Approximate mixing temperatures and compaction temperatures can be found in table

500-5 of this specification:

TABLE 3.2 MIXING TEMPERATURE AND COMPACTION TEMPERATURE

FOR DIFFERENT GRADE OF BITUMEN AS PER MoRT&H TABLE 500-5

Bitumen

penetration

Bitumen

Mixing

Aggregate

Mixing

Mixed

material(°C)

(Maximum)

Laying

temp(°C)

(minimum)

Rolling

temp (°C)

(minimum)

35 160-170 160-175 170 130 100

65 150-165 150-170 165 125 90

90 140-160 140-165 155 115 80

Therefore we tried for BC mix using for 60/70 grade bitumen and varying Mixing

temperature and Compaction temperature to test the effect on Marshall Properties of the

mix.

As per the above standard table the maximum mixing temperature is 165°C and minimum

compaction temperature is 90°C.

For the study we varied mixing temperature from 130°C to 180°C i.e. 130°C, 157.5°C &

180°C and also we varied compaction temperature from 70°C to 130°C i.e. 70°C ,

90°C,110°C& 130°C.



CHAPTER 4

TEST RESULTS AND OBSERVATIONS

4.1. Aggregates

The following tests were conducted on Aggregates and results are presented in the

Table no 4.1.1

TABLE-4.1.1 RESULTS OF TESTS ON PHYSICAL PROPERTIES OF

AGGREGATES

Sl. No. Property MoRT&H

specification

Results

1. Specific gravity

i) Coarse aggregate

ii) Fine aggregate

2.5-3 2.65

2.71

2. Aggregate impact value Max 24% 25.18 %

3. Los Angeles abrasion value Max 30% 28.76 %

4. Flakiness & Elongation index

(combined)

Max 30% 31.80

5. Water absorption Max 2% 0.5 %

6. Stripping value (coating of

bitumen retained)

Min 95% 99 %

a) Filler

Specific gravity of fillers have been evaluated and shown in Table 4.1.2

Table 4.1.2: Physical properties of fillers (Specific gravity)

Sl. No. Material Results

1. Cement 3.01



2. Quarry Dust 2.77

4.2. Bitumen

The bitumen used in this study is 60/70 grade bitumen. The engineering tests were

conducted and the results are presented in Table – 4.2

TABLE-4.2 RESULTS OF TESTS ON PHYSICAL PROPERTIES OF 60/70

GRADE BITUMEN

SI

No.

Property Value Requirements as per

IS: 73-2002

1 Penetration at 25°C 66 60-70

2 Softening point (R&B) (°C) 51 45-55

3 Ductility @27°C cm 100+ 75 min

4 Specific Gravity 0.9944 0.99

5 Flash point (°C) 210 175 min

The bituminous mix was designed by using Marshall Method of mix design. The

Marshall test is used to obtain the optimum bitumen content based on ASTM D-1559-96.



4.3.Marshall Properties of BC mix

TABLE 4.3 MARSHALL TEST RESULTS AT 60°C FOR 60/70 GRADE

BITUMEN AT STANDARD MIXING TEMPERATURE OF 160°C AND

COMPACTING TEMPERATURE OF 149°C

Bitumen

Content

(%)

Marshall

Stability

kg

Flow

Value,

mm

Bulk

Density

(Gb)

g/cm3

Total

Air

Voids

(Vv)

%

Voids filled

with

Mineral

Aggregate

(VMA)

%

Voids filled

with

Bitumen

(VFB)

%

5.00 1561 3.12 2.360 5.744 17.314 66.833

5.50 1904 3.63 2.377 4.426 17.244 74.333

6.00 1852 3.83 2.374 3.902 17.869 78.211

6.50 1581 4.50 2.371 3.388 18.500 82.214

GRAPHS OF BC MIXES USING 60/70 GRADE BITUMEN TO DETERMINE

OBC



Graph4.1: Bulk density Vs. Bitumen content

Graph 4.2: Marshall Stability vs. Bitumen content.

Graph4. 3: Air voids Vs. Bitumen content.



Graph 4.4: VFB Vs. Bitumen content.

Graph 4.5: Flow Vs. Bitumen content.



The bitumen content for the mix design is found by taking the average value of the

following three bitumen contents found from the graph of the test results.

1. Bitumen content corresponding to maximum stability.

2. Bitumen content corresponding to maximum unit weight.

3. Bitumen content corresponding to the median of designed limits of percent air

voids in the total mix (4%).

Hence the optimum bitumen content is (5.6+5.7+5.9)/3 = 5.73% ≈ 5.70%

TABLE 4.4 MARSHALL PROPERTIES AT OBTIMUM BINDER CONTENT

FOR MID LIMIT GRADATIONS OF BC USING 60/70 GRADE BITUMEN AT

60°C

Marshall Properties

Results of BC,

Grade - II mix

Requirements as per MoRT&H

Specifications

Optimum Binder Content, % 5.70 Min 5 %

Marshall stability at 60°C

kg

1919 900

Flow Value, mm 3.70 2 to 4

Bulk Density, g/cm3 2.382 ----

Air Voids, (Vv) % 4.547 3 to 6

VMA, % 17.78 14

VFB, % 74.427 65 to 75



4.4 Effect of varying Mixing & Compacting Temperature on

Marshall Properties:-

The results of the Marshall tests conducted on the bituminous concrete – II mix

with varying Mixing & Compacting Temperature have been shown in the following

tables. Here in Marshall Test, 75 blows of 4.5 kg weight on both sides are applied through

fall of 45.7 cm each time.

For the study we varied mixing temperature from 130°C to 180°C i.e. 130°C, 157.5°C &

180°C and also we varied compaction temperature from 70°C to 130°C i.e. 70°C ,

90°C,110°C& 130°C.



Table 4.5 Marshall Properties by keeping Constant Mixing Temperature of

130°C and by varying Compaction temperature for Bituminous Concrete Mix

Marshall

properties

Results at varying Compaction

temperature

Requirement as

per MoRT&H

Temperature(°C) 70°C 90°C 110°C 130°C

Blow 75 75 75 75 75

Optimum

Binder

Content (%)

5.70 5.70 5.70 5.70 5-7

Stability (kg) 930 1124 1282 1458 900

Flow (mm) 2.90 3.40 3.75 4.40 2-4

Bulk Density(g/cc) 2.242 2.293 2.332 2.376 -----------

Total air voids, Vv

%

9.614 7.550 5.987 4.321 3-6

VMA, % 22.143 20.366 19.019 17.506 13

VFB,% 56.588 62.944 68.523 75.929 65-75

Observations:-

1) Bitumen is having high viscosity thereby Mixing (i.e. Workability) is difficult at

130°C temperature and high total air voids.

2) Bulk density (g/cc) is less.

3) Stability will increase as the increase in compaction temperature.

4) Total Air voids Vv decrease in increase in temperature.




157.5°C and by varying Compaction temperature for Bituminous Concrete Mix

Marshall

properties


temperature

Requirement as

per MoRT&H


Blow 75 75 75 75 75

Optimum

Binder

Content (%)

5.70 5.70 5.70 5.70 5-7

Stability (kg) 1264 1617 1850 1899 900

Flow (mm) 3.25 3.55 3.85 4.30 2-4

Bulk

Density(g/cc)

2.335 2.372 2.394 2.394 -----------

Total air voids,

Vv %

5.861 4.358 3.501 3.497 3-6

VMA, % 18.910 17.616 16.878 16.874 13

VFB,% 69.012 75.263 79.310 79.279 65-75

Observations:-

1) Bitumen is having less viscosity thereby Mixing (i.e. Workability) is easy at

157.5°C temperature and total air voids is as per standard requirement.

2) Bulk density (g/cc) is increasing.

3) Stability will increase as the increase in temperature.

4) Total Air voids Vv decrease in increase in temperature.

5) At 157.5°C mixing temperature and 110°C & 130°C, mix fulfills all the

requirement of the BC grade-2





Marshall

properties


temperature

Requirement as

per MoRT&H


Blow 75 75 75 75 75

Optimum

Binder

Content (%)

5.70 5.70 5.70 5.70 5-7

Stability (kg) 1101 1151 1588 1619 900

Flow (mm) 3.25 3.70 4.25 4.40 2-4

Bulk

Density(g/cc)

2.326 2.356 2.373 2.387 -----------

Total air voids,

Vv %

6.227 5.034 4.338 3.774 3-6

VMA, % 19.226 18.198 17.599 17.113 13

VFB,% 67.618 72.346 75.349 77.982 65-75

Observations:-

1) Bitumen losses its physical properties(rheological property) at high temperature of

180°C therefore less stability and bulk density compared to mixing temperature

157.5 °C

2) less stability and bulk density compared to mixing temperature 157.5 °C



Graph 4.6: Effect of Mixing and compaction temperature to the Bulk specific

gravity of the BC mix

Graph 4.7: Effect of Mixing and compaction temperature to the Marshall stability

of the BC mix



CHAPTER 5

DISCUSSIONS AND CONCLUSIONS

5.1. PHYSICAL PROPERTIES:

1) Results of physical properties of the aggregates used for present study are

presented in table 4.1 and test results are satisfying the requirements as per Table

500-17 of MoRT&H (IV Revision) specifications.

2) The physical properties of the Plain binder used for this study were tested and are

presented in table 4.2 respectively and the test results are satisfying the

requirements as per IS: 73-1992 for plain bitumen.

5.2. MARSHALL TEST:

From Marshall Mix design, optimum bitumen content is 5.7% for a Bituminous

Concrete mix and it was meeting the requirement as per the MoRT&H IV revision

specifications Table 500-18 & Table 500-19

5.2.1 Marshall Properties by keeping Constant Mixing Temperature of 130°C

and by varying Compaction temperature for Bituminous Concrete Mix

1) Bitumen is having high viscosity thereby Mixing (i.e. Workability) is difficult at

130°C temperature and high total air voids.

2) Bulk Specific gravity value at mixing temperature 70°C, 90°C, 110°C and 130°C

were found to be 2.242, 2.293, 2.332 and 2.376.

3) Stability value at mixing temperature 70°C, 90°C, 110°C and 130°C were found

to be 930, 1124, 1282 and 1458 thereby Stability will increase as the increase in

compaction temperature.



5.2.2 Marshall Properties by keeping Constant Mixing Temperature of

157.5°C and by varying Compaction temperature for Bituminous Concrete Mix

1) Bulk Specific gravity value at compaction temperature 70°C, 90°C, 110°C and

130°C were found to 2.335, 2.372, 2.394 and 2.394.

2) Stability value at compaction temperature 70°C, 90°C, 110°C and 130°C were

found to be 1264, 1617, 1850 and 1899, which gives maximum stability

3) With the increase in temperature from 70 to 130°C degrees the air voids are

reduced by 5.861,4.358,3.501 and 3.497% respectively, Due to reduction in air

voids there is increase in VFB

5.2.3 Marshall Properties by keeping Constant Mixing Temperature of


1) Bitumen losses its physical properties (rheological property) at high temperature

of 180°C therefore less stability and bulk density compared to mixing temperature

157.5 °C

2) Bulk Specific gravity value at compaction temperature 70°C, 90°C, 110°C and

130°C were found to 2.326, 2.356, 2.373 and 2.387

3) Stability value at compaction temperature 70°C, 90°C, 110°C and 130°C were

found to be 1101, 1151, 1588 and 1619.

4) With the increase in compaction temperature from 70 to 130°C degrees the air

voids are reduced by 6.227, 5.034, 4.338 and 3.774% respectively.



5.3 CONCLUSION:-

1) Flow of the mix reduces with reduction in Mixing & Compaction temperatures. The

workability of the mix will reduce in the field.

2) There is an increase in air voids, which will increase the cracks and there will be

undulations on the surface (wearing) course.

3) Voids filled with bitumen will increase, due to increase in mixing temperature &

compaction temperatures.

4) Voids in mineral aggregate(VMA) decreases with the increase in compaction

temperature

5.4 RECOMMENDATION

The ideal mixing temperature for BC grade-2 comes out to be 157.5°C (i.e. in between

150 to 165°C)

The ideal compaction temperature for BC grade-2 comes out to be 110°C & 130°C as per

results of this study.



CHAPTER 6

REFERENCES

1. Larry AK Silas Tirau, "Evaluation of Hot Mix Asphalt (HMA) properties

compacted at various temperatures", project report, November-2005.

2. Dr.H.C.Mehndiratta & Praveen kumar , “Effect of Mixing and Compacting

temperatures on marshall parameters of bituminous mixes”.

3. Khanna.S.K., And Justo.C.E.G, "Highway material testing Manual", Nemchand

and Brothers Publications, Roorkee2002,

4. Khanna.S.K., And Justo.C.E.G, "Highway Engineering" 8th Edition, Nemchand

and Brothers Publications, Roorkee2001

5. Specifications of Road and Bridge Works Ministry of Road Transport and

Highways (MoRT&H), Govt of India, Fourth Edition, 2001.

6. L. Michael H. Hunerand E.R. Brown, "Effects of Re-heating and compaction

temperature on hot mix asphalt volumetric", NCAT Auburn University,

November-2001.


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