from crude oil to application: a low temperature and aging ...€¦ · 20/30, 50/70, 70/100 as well...

2018 Test and Measurement Conference

From Crude Oil to Application: A Low Temperature and Aging Nexus

Approach to Material Memory

Speaker / Author: Keith D. Nare

Co-author: Shanganyane P. Hlangothi

Centre for Rubber Science and Technology

Nelson Mandela University

PO Box 77000, Summerstrand, Port Elizabeth, 6031, South Africa

e-mail: [email protected]

Phone: 041 504 2380 Fax: 041 504 2574

Abstract

Creep and deflection associated with thermal changes gradually develops as temperature

drops and can be simulated using a thermoelectric bending beam rheometer. Fundamentals of

the elementary beam theory and the elastic-viscoelastic correspondence principle give the

basis for understanding time dependent flexural-creep behavior of bitumen. Being a by-

product of crude oil distillation at refineries, the effects of origin and refining technology play

a critical role in understanding chemistry related to material memory and fingerprint.

Spanning across a variety of neat and modified binders, material exposure to low temperature

and age state is important in predicting in-service and longevity behavior of the road. In

accordance to South African proposed framework on performance related specifications in

practice, studies performed on the bending beam rheometer highlight the low temperature and

aging nexus as related to material memory. Understanding inherent material signatures helps

in better decision making leading to informed choices and major cost savings in the life cycle

of your road. The thermal history of the binder in addition to cycles of short term and long

term aging contributes to the changes over time from source to application of the parent

binder. In essence, binder rheology depicted in free shifted stiffness isotherms plots together

with parameters such as aging indices and critical temperatures are used in the study to

understand changes in the material with aging and relaxation processes based on binder

composition. The basis of establishing a fingerprint using the bending beam rheometer is to

aid in identifying the source of the parent binder in either unknown or modified binders; thus

enabling binder traceability and contributes to the performance grading of the binders. Neat

20/30, 50/70, 70/100 as well as crumb rubber, styrene butadiene styrene and ethylene vinyl

acetate modified binders were used in this study.

1. Introduction

Bitumen quality affects its performance as a road construction material. Variability in

fractional composition stems from changes associated with processing and crude sources [1].

According to media [2] and technical reports [3], 45% of South Africa’s crude oil comes

from Saudi Arabia, a further 23% from Nigeria, 18% from Angola, 4% from Ghana, with the

trade-off of 10% from other sources. Although world politics can shift the demand and

supply of crude oil, operating capacity at local refineries (currently at a maximum average of

80%) also affects its import. Nonetheless, since fractional composition is dependent on the

crude source, the fingerprint and memory of the bitumen by-product is also unique to the

crude oil type, with capacity and refining technology adding onto the variation.

Peer-reviewed manuscriptTest and Measurement 2018 Conference and Workshop


Dating back to the early 90s, Anderson et al. [4] introduced the bending beam rheometer

(BBR) as part of the Strategic Highway Research Program (SHRP) for stress controlled direct

measurement of the bitumen at the lowest pavement temperature [5]. The BBR has been used

since to generate bitumen, modified bitumen and asphalt data and their inferences on creep

stiffness (S) and creep rate (m) as related to performance criterion [6]. In the interest of

characterisation it would be misleading to have a materials chemistry blind approach to the

source, modifier and thermal history of the bitumen under analysis. South Africa has recently

introduced performance grade (PG) bitumen testing and protocols with emphasis on grading

based on the age state of the binder; harnessing both an empirical testing basis coupled with a

transition to performance related testing. The use of the BBR [7] in PG testing is on residue

exposed to short and long term aging via the rolling thin film oven test [8] and the pressure

aging vessel [9] respectively.

The BBR finds its applications in municipal waste modified bitumen [10], crumb rubber

modified bitumen [11], fracture and moisture damage characteristics of 70/100 bitumen with

loadings of warm mix additives [12] and polyethylene wax modified bitumen [13]. In

addition, it can be used to measure bitumen emulsion PG grading of the material associated

with poly-phosphoric acid induced physical hardening [14], as well as its effect on aged

asphalt concrete [19]. Compared to other instrumentation approaches, BBR can be used as an

alternative to both the bending beam creep tests for asphalt mixtures [15] and the dynamic

shear rheometer (DSR) with 4mm parallel plates [16]. With regard to thermal analysis, BBR

can be an alternative to differential scanning calorimetry (DSC) in determining low

temperature properties and glass transition temperature of bitumen [17]. For example, BBR

was used in determining the engineering behaviour of bitumen loaded with mineral filler [18]

as well as low temperature properties of styrene butadience styrene (SBS) polymer modified

bitumen [20], amongst many others.

Marasteanu et al. [21] reported that critical temperature and limiting temperature from the S

and m values of the BBR are considerably affected by physical hardening. For determining

the single event cracking temperature directly from the BBR, Shenoy [22] proposed a

procedure which uses pavement thermal stresses from the BBR binder stiffness data to

calculate two asymptotic thermal stresses build up rates which directly identifies the cracking

temperature. In essence the BBR becomes a stand-alone device for low temperature binder

specification determination. Understanding bituminous binders relaxation properties at low

temperatures has led to advanced techniques for master curve development from the BBR.

Rowe et al. [23] identified that the discrete spectrum fit is the best method for fitting a master

curve, however with limitations of non-extrapolation beyond the range over which data is

collected. In the early 2000s, the Christensen-Anderson-Sharrock method was given as the

best functional from for fitting BBR data owing to the lowest root mean square errors and the

least bias in the test results [23].

Marasteanu and Anderson [24] discarded the use of pseudo black diagrams with BBR data

because of errors in calculating m-values associated with the use of polynomial

approximation. The c-coefficient can be used as a quick check of BBR data on the basis of

the fact that the slope of the m-values decreases as the test temperature decreases. ∆Tc

parameter is age dependent and indicates the tendency of either S-controlled or m-controlled

binders with preference for the former as they generally have better relaxation properties

leading to better performance [25]. Christensen et al. [26] proposed that the R-value

(rheological index) is linked to binder behaviour related to fatigue resistance, chemical

composition and the degree of oxidative aging. This was depicted in the shape and skewness


of the spectrum. King et al. [27] and Rowe et al. [28] reinforced the R-value as an aging

function highlighting whether aging trends would translate to mixture properties as evidenced

by the shape of relaxation spectra and the ability to relax stress.

In this study, thermo-rheological properties of neat and polymer-modified binders sourced

from different refineries in South Africa were analysed. The binders used were short and

long-term aged through the rolling thing film oven test, modified rolling thin oven test and

pressure aging vessel [29].

2. Materials and methods

2.1 Materials

The particular selected seal and asphalt binders for the study consisted of 9 samples namely:

20/30, 50/70, 70/100, S-E1, S-E2, A-E1, A-E2, A-P1 and NCRT (New Crumb Rubber

Technology). Governing the selection was the inclusion of most seal and asphalt binders

commonly used in different parts of the country. The following is a background to the binders

and where they were sourced:

Neat binders:

20/30, Acoustex, Eastern Cape, parent binder sourced from Sapref refinery.

50/70, Much Asphalt, Gauteng, parent binder sourced from Natref refinery.

70/100, Much Asphalt, Western Cape, parent binder sourced from Chevron refinery.

Styrene butadiene styrene modified binders:

S-E1, Colas, Eastern Cape, parent binder sourced from Chevron refinery.

S-E2, Colas, Eastern Cape, parent binder sourced from Sapref refinery.

A-E1, Much Asphalt, Eastern Cape, parent binder sourced from Chevron refinery.

A-E2, Much Asphalt, Eastern Cape, parent binder sourced from Chevron refinery.

Ethylene vinyl acetate modified binder:

A-P1 from Colas in the Eastern Cape, parent binder sourced from Chevron refinery.

Crumb rubber modified binder:

NCRT from Tosas in Bloemfontein, parent binder sourced from Sapref refinery.

2.2 Methods

The aging conditioning and the rheological testing were conducted at the Nelson Mandela

University bitumen laboratory and at the SANRAL Technical Excellence Academy

laboratories in the Eastern Cape, respectively. Specific instrumentation, methods and

procedures are given as follows:

2.2.1 Instrumentation

The instruments used in the study include:

Rolling Thin Film Oven (RTFO);

Pressure Aging Vessel (PAV) and Vacuum Degassing Oven (VDO); and

Thermoelectric Bending Beam Rheometer (BBR).


2.2.2 Experimental design

The thought process behind the experimental design included the goals of the testing

procedure and the sample preparation. The steps taken to test and age the binders are given in

the flow chart shown in Figure 1.

Figure 1: Experimental design flow chart to depict the regime of testing for the nine binders.

2.2.3 Goal of the testing procedure

The main objective was the thermorheological analysis of low temperature and aging nexus

of the nine binders. Progression in the binder age state as simulated by short term and long

term aging and rheological behaviour at low temperatures was paramount for further

inferences. The binder fingerprint would assist in revealing the nature of the material memory

associated with the origin and additive nature relating to the chemistry of the related changes

because of the aging regime. The binder thermal history and material memory were evaluated

in the following ways:

Low temperature aging indices approach to changes from a neat binder, RTFO and

PAV aged binders.

The S and m approach to binder analysis through BBR experimental data.

2.2.4 Sample preparation

All neat and modified bitumen samples were varied across different suppliers in the country.

In the interest of minimizing the thermal history of binders, samples were heated prior the full

regime of testing with neat, modified and NCRT binders heated at 160 ºC, 170

ºC and 180

ºC

respectively. The regime of heating was conducted for 1 hour followed by sample

homogenising using a laboratory mixer fitted with a dual helical impeller prior use in the

testing. The BBR beam preparation was conducted in aluminium moulds according to ASTM

standard [7]. Samples were then cooled to approximately -5ºC for 1 minute and demoulded.

After demoulding, the sample beam was immersed in a constant temperature methanol bath

and kept at each test temperature for 30 minutes.

2.3 Aging of binders

Age hardening affects durability of bituminous binders. It is manifested as an increase in

stiffness reflected in viscosity measurements and is highly dependent on temperature, time

and thickness of bitumen film. Characteristics of aging is either physical and/or exudative

20/30 50/70 70/100 S-E2S-E1 A-E2A-E1 NCRTA-P1

BBR RTFO BBR

PAV

neat binder RTFO binder

VDO

PAV binder


hardening due to loss of volatile components and oxidation during construction (short term)

and in-field after construction (long term). As a result, extended heating procedures are

performed to correlate accelerated laboratory aging with field performance. In this study, the

aging of binders was done in the RTFO and PAV. The RTFO was for the short term aging

whereas the PAV was for the long term aging. Residue from the RTFO was used in the PAV

and after the PAV aging, the residue was taken to the Vacuum Degassing Oven after which

the sample was ready to be tested in the BBR.

2.3.1 Rolling Thin Film Oven

Introduced as a significant modification of the Thin Film Oven Test (TFOT), the RTFO test

involved placing bitumen in glass jars and rotating 1.25 mm thin films relative to the TFOT

3.2 mm films to simulate bitumen hardening. The method adopted in this study was the one

developed by the California Division of Highways, where about 35 g of neat bitumen was

placed in vertically rotating shelf while blowing hot air into each sample bottle at its lowest

travel position. The amount of hardening in RTFOT correlates with conventional batch

mixer. For the modified binders, the Modified Rolling Thin Film Oven Test (RTFOTM) was

developed by Bahia as an improvement for highly viscous binders failing to roll inside the

glass bottles and overcome binders rolling out of the bottles. This method is identical to the

RTFOT except that a set of 127 mm long by 6.4 mm diameter steel rods was placed inside

brass containers. Steel rods create the shearing forces to spread the binder into thin films and

help in overcoming the problem of aging high binder viscosity. [8,29,30].

2.3.2 Pressure Aging Vessel

The Pressure Aging Vessel test was developed by the SHRP-A-002A research team to

simulate the long term, in-service oxidative aging. In this method, the RTFOT/RTFOTM

conditioning comes first, followed by oxidation of residue in the PAV. The process involves

placing about 50 g of sample in 140 mm diameter pan, 3.2 mm binder film, with air

pressurized to 2±0.1 MPa for 20 h at temperatures between 90 and 110 ˚C [30]. The residue

from the PAV was heated at 170 ºC prior degassing in the Vacuum Degassing Oven (VDO)

for 30 minutes to remove entrapped air. If not degassed, entrapped air bubbles may cause

premature breaking in the Direct Tension Test [9,30].

2.3.3 Bending Beam Rheometer

The Bending Beam Rheometer was introduced as a binder test in the Strategic Highway

Research Program. It has been incorporated in the performance grade specification to

determine binder stiffness at 60 seconds and the slope of stiffness curve, log time versus log

stiffness, gives the m-value. In essence its development was to overcome testing problems

common with other methods when testing stiff binder at low temperatures [23]. The binder

tests were carried out on different temperatures ranging from 0 ºC to -24 ºC with -6 ºC

increments representing the low temperature binder grade [22]. A constant load of 100 g was

applied to the rectangular beam sample supported by stainless steel rounds and the deflection

at the centre point was measured continuously. Creep stiffness (S) and creep rate (m) were

measured at different loading times spanning from 8 to 240 seconds [17]. The final result is

the performance grade limiting temperature determined from stiffness and m-value,

representing the slope of stiffness versus time curve in a double logarithm plot. Both values

are determined for the time loading at 60 seconds [7,15].


2.4 Data analyses

The proposed hypothesis of the study was based on the assumption that as binder ages, low

temperature relaxation properties disintegrate more rapidly than stiffness. The decline in the

m-value shows that the binder flow ability is limited to heat distress accumulating in the mix.

Validation of the hypothesis through binder testing is reflected in BBR critical temperature

for m-value deteriorating faster than the critical temperature for stiffness during PAV aging.

BBR test data from samples conditioned in the RTFOT and PAV were used for generation of

free shifted stiffness isotherms in Microsoft Excel. Numerical stability within the constraints

of testing was the basis used for the selection of test data used in the analysis. The approach

to use isotherms of stiffness, S(t) was taken and applied to obtain multiple BBR isotherms. In

the process, it obtained shift factors where stiffness data at six loading times between 8 and

240 s for every test temperature was shifted horizontally on the log time scale. This formed a

smooth reasonable overlap, which according to Gordon and Shaw’s method can be used to

obtain free-shifted stiffness isotherms for all binders at a particular reference temperature.

The temperature dependency of the shift factors was modelled using Arrhenius equation [23].

2.5 Research constraints and areas of growth

The availability of the RTFOT, PAV and BBR was at a separate testing facility to the

institution given the scarcity of such instrumentation in the Eastern Cape and the

country at large.

The cleaning of the BBR aluminium moulds posed a huge challenge with stubborn

residual solvent that remained even after cleaning. A final flush clean with acetone

helped in the process.

Unavailability of the RHEA Software to convert the BBR data to G* using the

Hopkins and Hamming method limited the application of black space plots and master

curve development. The sole focus was the BBR, though if available it would have

been great to use merged DSR data to construct master curves.

BBR data was difficult to obtain for neat binders, hence the need to test RTFOT and

PAV conditioned samples to track the changes in aging prior conditioning.

Grease on the mylar strips if not prepared well in the beam demoulding stage would

give skew dimension to the beam which would lead to erroneous results.

The use of the probe thermometer was inevitable so as to compare the actual temperature

of the bath relative to what is being recorded on the software as well, given that one has

to calibrate at every test temperature.

The importance of a temperature controlled room especially in summer where the

heat/water unit would not flange down to allow for reaching the desired low temperature.

Adhering to the limit of all the testing to be done within 4 hours of preparation was very

important for the reliability of results.

Importance of shutting down the machine properly to avoid solvent rise and emphasis on

the shutting down temperature to avoid solvent level engulfing the load cell.

3. Results and Discussions

3.1 Free shifting isotherms

The development of Gordon and Shaw free-shifting isotherms was based on the similarity in

reference temperature to match the temperature dependency of the shift factors across all


samples regardless of the binder. The RTFOT and PAV aged binders under the regime of low

temperature testing had reference temperatures -12ºC (20/30, A-E2 and A-P1), -18 ºC (50/70,

70/100, S-E1, S-E2 and A-E2) and -24 ºC (NCRT). Figures 2, 3 and 4 depict the free shifting

isotherms for all the binders used in the study.

Figure 2: Modified Gordon and Shaw free shifting isotherms for 20/30, A-E2 and A-P1

binders.

At reference temperature -12 ºC, 20/30 was more susceptible to aging relative to A-E2 and A-

P1. Given that 20/30 is a neat binder, at low temperatures the effects of short and long term

aging tend to proliferate more as opposed to the other two binders. The A-P1 binder was not

far off from the 20/30 binder. Given the nature of the EVA plastomer additive, the

disintegration of the plastomeric backbone at accelerated conditions could have led to the

increased aging tendency to be more inclined towards the 20/30 binder. A 3D rigid network is

generally formed for plastomers in bitumen, with ethylene and vinyl acetate moieties

breaking down. The interaction with the oxidized bitumen molecules after PAV aging affects

binder homogeneity, hence remaining unstable during aging. Ultimately, this renders more

parent bitumen hardening and minimal participation of plastomer in the bitumen aging

mechanism. The bitumen rich phase of the modified binder is what is exposed more to the

effects of short and long term aging in the case of the A-P1. EVA as a bitumen modifier is

known to have limited improvement in low-temperature properties due to its significantly

high glass transition temperature which is strongly dependent on vinyl acetate content and

elastic recovery owing to its plastomeric nature. A further low melting temperature of the

ethylene domains in the EVA disintegrates on shearing through preparation [31,32]. Of all

the three binders, at a particular reference temperature, the SBS modified A-E2 showed the

least susceptibility to aging at low temperatures as shown in Figure 2.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5 6

log

S (

MP

a)

log reduced time (s) Tref -12˚C

20/30

20/30

20/30

A-E2

A-E2

A-E2

A-P1

A-P1

A-P1


Figure 3: Modified Gordon and Shaw free shifting isotherms for 50/70, 70/100, S-E1, S-E2

and A-E1 binders.

Figure 3 shows the Gordon and Shaw free shifting isotherms at a reference temperature of -

18 ºC. The source of neat bitumen could have played a huge role in the aging susceptibility

of 50/70 relative to 70/100. Unique to the parent binder would be the chemistry associated

with the loss in volatiles associated with distribution of SARA fractions in the bitumen. 50/70

is found to be more prone to aging and indeed reflected in its low temperature behaviour in

the modified Gordon and Shaw free shifting isotherms in Figure 3. The aging resistance is

improved by modification, which is evident in the S-E1, S-E2 and A-E1. SBS is elastomeric

in nature and confers the modified bitumen improved low temperature relaxation properties

based on the loading of SBS, which is subject to temperature sensitivity for the different SBS

modified binders. The distinction amongst the three SBS modified binders is based on

different applications for seals and asphalt, thus the possibly of additives associated with

asphalt leading to the most aging resistance at the reference temperature. S-E1 and S-E2

binders are prone to less thermal degradation during the chip seal spraying process, with A-

E1 binders subjected to thin film oxidation in the coating drum and when paving in the hot

mix applications. Hence severity in degradation is prevalent in A-E1 binders during

manufacture and application.

In the case of NCRT, the nature of the additive played a huge role due to the composite

nature of crumb rubber and loadings of warm mix FT wax used in the modification of

bitumen. Figure 4 shows the modified Gordon and Shaw free shifting isotherms for NCRT

binder. Kim and Lee [34] reported that rubber can be used to improve the cracking resistance

of asphalt binders modified with wax. Fazaeli et al. [35] showed that among all additives,

Sasobit and crumb rubber combination exhibited the best performance at low and

intermediate temperatures. The authors reported that crumb rubber provided an elastomeric

backbone for the modified binder with increased elasticity. In addition, the compositional

variations in crumb rubber from a highly engineered passenger or truck tyre would bring up

the dynamic of carbon black, which is an antioxidant and is effective in crack resistance in

the low temperatures. The resistance to aging at low temperatures can be associated with

modification of bitumen with crumb rubber and FT wax. Specific technical requirements at

low temperatures should lead to binder formulation for the particular engineering application.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5 6

log

S (

MP

a)


50/70

50/70

50/70

70/100

70/100

70/100

S-E1

S-E1

S-E1

S-E2

S-E2

S-E2

A-E1

A-E1

A-E1


3.2 Limiting temperatures and ∆Tc

Figure 4: Modified Gordon and Shaw free shifting isotherms for NCRT binder.

Baumgardner et al. [36] suggests that at temperatures close to or below the glass transition

temperature (Tg), a reversible effect with heating occurs where mixture beams decrease in

stiffness with time at a constant temperature. Lu and Isacsson [33] proposed that Tg

determined using BBR limiting temperatures is greatly dependent on source and grade of

bitumen. A decrease in Tg is noted on polymer modification with negative influence on the

limiting temperatures. Lu and Isacsson [37] reported that SBS modification causes a

reduction in the Tg with Masson et al. [38] indicating that relative to the polystyrene moiety,

the polybutadiene moiety has good interaction with bitumen, which improves miscibility. Anderson et al. [4] described the isothermal aging at low temperatures as a metastable

structural state near or below Tg as a slow and time dependent structural relaxation process

driven by the bias in internal energy leading to changes in material properties.

Modulated Differential Scanning Calorimetry (MDSC) studies [39,40], in the reversing heat

flow curve, revealed two Tgs in bitumen. The first transition at -20 ºC was attributed to the

SARA fraction of maltenes and the other in the temperature range of 53 ºC and 70 ºC was

assigned to asphaltenes. The inclusion of S and m parameters in determining the difference

between the continuous grading for the m-value and stiffness (Ts-Tm,) goes back to the SHRP

validation report which upon plotting BBR stiffness vs the m-value showed that neither

parameter was solely responsible for the rejection of the binders [28]. Table 1 summarises the

performance grade limiting temperatures and ∆Tc for the 9 binders used in this study. The

performance grade limiting temperatures include the stiffness limiting temperature at S(60s)

= 300 MPa, -10 ºC; whereas the m-value limiting temperature is at m(60s) = 0.3 min, 10 ºC.

Implications of long term aging to low temperature performance of the binders as related to

material characteristics gives a better understanding of how the different binders behave

under such conditions.

Most of the binders in Table 2 were found to be m-controlled binders. Given similar stiffness

levels, increased m-values led to faster development of thermal stresses. In the performance

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5 6

log

S (

MP

a)


NCRT

NCRT

NCRT


grade criterion for reasonable low temperature climates, elevated m-value binders have been

found to perform better due to more relaxation occurring in the extended period of time [41].

The approach of looking at the m-value in that regard is by virtue of being the rate of change

of stiffness that is associated with inherent relaxation properties of the binders.

Table 1: Representation of the limiting temperatures and ∆Tc for the 9 binders used in the

study according to [25].

Binder Type

Limiting Temperature (-10 ºC) Ts-Tm

S(60s) m(60s) ∆Tc

20/30 Neat -17.3 -17.2 -0.1

50/70 Neat -22.8 -22.4 -0.4

70/100 Neat -25.7 -24.0 -1.7

S-E1 Elastomer -27.9 -24.1 -3.8

S-E2 Elastomer -26.9 -19.0 -7.9

A-E1 Elastomer -28.6 -23.4 -5.2

A-E2 Elastomer -22.3 -19.0 -3.3

A-P1 Plastomer -19.5 -16.7 -2.8

NCRT Elastomer* -33.3 -26.2 -7.1 *NCRT contains loadings of FT wax which introduces a plastomeric component to the binder

The criterion for obtaining ∆Tc involves the use of two adjacent specification grading

temperatures with limits that one value passes and the other fails the requirement for both S

and m-value.

According to the South African performance grade specification, the ∆Tc should be less than -

5 ºC. However, values greater than -5 ºC were obtained for S-E2 and NCRT as a result of

failure in both m-values when calculating the limiting temperature for m. A-E2 also failed

owing to failing in the stiffness value to meet the pass criteria. However, A-E1 has a value of

-3.3 ºC, which is a pass value even though the stiffness value did not meet the criterion. The

rest of the binders did conform to the pass fail criteria for both the S and m-value from the

BBR data. Critical temperature and limiting temperature from the BBR S and m-values are

mainly affected by physical hardening; hence proper sample preparation was critical because

testing in the BBR contributes to the results of the creep test.

3.3 Aging Indices

Aging indices are taken to be an arbitrary measurement of material changes that take place

from the neat, short and long term aged binders. The expected trend would be an increase in

stiffness as a result of each conditioning stage which reflects in the percentage change in

aging. Figure 5 shows the percentage change in aging for 8 of the binders with change

depicted from RTFOT to PAV. The values of the aging indices used for the percentage

change in aging were performed at -12ºC which for the NCRT sample was above the

temperature at which the RTFO and PAV aged temperature was measured.

The A-E1 and A-E2 binders showed the least susceptibility in aging behaviour at the test

temperature, with the former showing no changes in aging and the latter showing a negative

percentage change in aging with RTFO and PAV conditioning. The A-P1 showed the most

susceptibility to effects of changes from the short term to the long term aging heavily

reflected in the 74% incremental change in aging. S-E2 showed the second most


susceptibility with move from short term to long term aging at 64%. The percentage change

in aging from short term to long term aging at low temperatures was to depict the nature of

the effects of binder changes when moving from workability to an in-service approach in

general when considering performance parameters. The integrity of the modifier moieties,

loss of material memory and finger print could have contributed to the behaviour of the

binders shown in Figure 5.

Figure 5: Percentage change in aging from RTFO to PAV aged binders reflecting effects of

aging conditioning on the binders.

4. Conclusion

The nexus to low temperature and accelerated laboratory aging based on the unique binder

finger-print and memory led to the following summary of conclusions and recommendations:

The source of binder, type of modifier and thermal history plays a pivotal role in low

temperature rheological properties measured at different stages of short term and long

term aging.

The contribution of stiffness and rate of change in stiffness is critical in the low

temperature rheology approach to effects of aging at different isothermal temperatures

The S > 300 MPa and m > 0.300 criterion in calculation of ∆Tc impacts on the -5 ºC

limit for the performance grade specifications which was the case for S-E2 and

NCRT.

Tracking low temperature incremental aging changes through aging indices and

percentage change in aging reflects aging susceptibility in the binders.

The BBR can be used as a stand-alone instrument to measure low temperature

performance of neat, RTFO and PAV aged binders.

Recommended for further study would be the merged BBR and DSR data for master curve

development and black space plots. The inclusion of MDSC data is to highlight the

importance of thermal history and modification on the Tg and its effects on SARA fractions in

the binder.

29

2228

77

0

-35

12

64

-60

-40

-20

0

20

40

60

80

100

(20/30) (50/70) (70/100) (A-P1) (A-E1) (A-E2) (S-E1) (S-E2)

Percentage Change


5. References

1. M. Paliukaite, A. Vaitkus and A. Zofka, “Evaluation of bitumen fractional composition

depending on the crude oil type and production technology”, The 9th

International

Conference of Environmental Engineering, Vilnius, Lithuania, 22-23 May 2014, pages

1 to 8

2. SA dependence on petrol imports growing - https://www.fin24.com/Economy/SA-

dependence-on-petrol-imports-growing-20140902

3. Sources of crude oil for SAPIA members: 2003 to 2015 –

www.sapia.org.za/Portals/_default/AnnualReport2015/SAPIA_AR_2015_FA-

spread.pdf

4. D. A. Anderson, D. W. Christensen, H. U. Bahia, R. Dongre, M. G. Sharma, C. E.

Antle and J. Button, “Binder characterisation and evaluation: Physical

characterisation”, Strategic Highway Research Program A-369 markup, 3, 1994, pages

123 to 137.

5. H. U. Bahia and D. A. Anderson, “Development of the BBR Basics and Critical

Evaluation of the Rheometer”, ASTM Special Technical Publication, STP1241, 1995,

pages 28 to 50.

6. M. R. Kaymanesh, H. Ziari and B. Damyar, “Effect of waste EVA and waste CR on

characteristics of bitumen”, Petroleum Science and Technology, 35:15, 2017, pages

1537 to 1541.

7. ASTM D6648-08 (2016), “Standard Test Method for Determining the Flexural Creep

Stiffness of Asphalt Binder Using the Bending Beam Rheometer (BBR)”, ASTM

International, West Conshohocken, PA, 2016.

8. ASTM D2872-12e1, “Standard Test Method for Effect of Heat and Air on a Moving

Film of Asphalt (Rolling Thin-Film Oven Test)”, ASTM International, West

Conshohocken, PA, 2012.

9. ASTM D6521, “Standard Practice for Accelerated Aging of Asphalt Binder Using a

Pressurized Aging Vessel (PAV)”, ASTM International, West Conshohocken, PA,

2013.

10. M.N. Amin, M.I. Khan, and M.U. Saleem, “Performance Evaluation of Asphalt

Modified with Municipal Wastes for Sustainable Pavement Construction”,

Sustainability, 8 (10), September 2016, pages 949 to 962.

11. H.H. Kim and S. Lee, “Evaluation of rubber influence on the cracking resistance of

crumb rubber modified binders with wax additives”, Canadian Journal of Civil

Engineering, 43 (4), January 2016, pages 326 to 333.

https://www.fin24.com/Economy/SA-dependence-on-petrol-imports-growing-20140902

https://www.fin24.com/Economy/SA-dependence-on-petrol-imports-growing-20140902

http://www.sapia.org.za/Portals/_default/AnnualReport2015/SAPIA_AR_2015_FA-spread.pdf

http://www.sapia.org.za/Portals/_default/AnnualReport2015/SAPIA_AR_2015_FA-spread.pdf


12. P.K. Das, Y. Tasdemir, and B. Birgisson, “Evaluation of fracture and moisture damage

performance of wax modified asphalt mixtures”, Road Materials and Pavement Design,

13 (1), March 2012, pages 142 to 155.

13. Y. Tasdemir, “High temperature properties of wax modified binders and asphalt

mixtures”, Construction and Building Materials, 23 (10), June 2009, pages 3220 to

3224.

14. T.R. Clyne, M.O. Marasteanu, and A. Basu, “Evaluation of Asphalt Binders Used for

Emulsions”, Minnesota Department of Transport, August 2003, pages 1 to 62.

15. M. Pszczola, M. Jaczewski, D. Rys, P. Jaskula, and C. Szydlowski, “Evaluation of

Asphalt Mixture Low-Temperature Performance in Bending Beam Creep Test”,

Materials (Basel), 11 (1), January 2018, pages 1 to 21.

16. X. Lu, P. Uhlback, and H. Soenen, “Investigation of bitumen low temperature

properties using a DSR with 4mm parallel plates”, International Journal of Pavement

Research and Technology, 10, August 2016, pages 15 to 22.

17. X. Lu and U. Isacsson, “Effect of Binder Rheology on the Low Temperature Cracking

of Asphalt Mixtures”, Road Materials and Pavement Design, 2 (1), January 2001, pages

29 to 47.

18. J.S. Chen, P.H. Kuo, P.S. Lin, C.C. Huang, and K.Y. Lin, “Experiments and theoretical

characterisation of the engineering behaviour of bitumen mixed with mineral filler”,

Materials and Structures, 41 (6), September 2008, pages 1015 to 1024.

,

19. A. Braham, I. L. Howard, J. Barham, and B.C. Cox, “Characterising emulsion effects

on aged asphalt concrete surfaces using BBR mixture beams”, International Journal of

Pavement Engineering, 16 (7), February 2014, pages 620 to 631.

20. X. Lu, U. Isacsson, and J. Ekblad, “Low temperature properties of SBS polymer

modified bitumen”, Construction and Building Materials, 12 (8), August 1998, pages

405 to 414.

21. M. O. Marasteanu, A. Basu, S.A.M. Hesp, and V. Voller, “Time-Temperature

Superposition and AASHTO MP1a Critical Temperature for Low Temperature

Cracking” International Journal of Pavement Engineering, 5 (1), February 2004, pages

31 to 38.

22. A. Shenoy, “Single-Event Cracking Temperature of Asphalt Pavements Directly from

Bending Beam Rheometer Data”, Journal of Transportation Engineering, 128 (5),

September 2012, pages 465 to 471.

23. G.M. Rowe, M.J. Sharrock, M.G. Bouldin, and R.N. Dongre, “Advanced Techniques to

Develop Asphalt Master Curves from the Bending Beam Rheometer”, Petroleum and

Coal, 43 (1), 2001, pages 54 to 59.


24. M.O. Marasteanu and D.A. Anderson, “Techniques for Determining Errors in Asphalt

Binder Rheological Data”, Journal of the Transportation Research Board, 1766,

October 2001, pages 32 to 39.

25. ASTM D7643-16, “Standard Practice for Determining the Continuous Grading

Temperatures and Continuous Grades for PG-Graded Asphalt Binders”, ASTM

International, West Conshohocken, PA, 2016.

26. D.W. Christensen, D.A. Anderson and G. Rowe, “Relaxation Spectra of Asphalt

Binders and Christensen-Anderson Rheological Model”, Road Materials and Pavement

Design, 18:sup1, January 2017, pages 382 to 403.

27. G. King, M. Anderson, D. Hanson and P. Blankenship, “Using Black Space Diagrams

to Predict Age-Induced Cracking” 7th

RILEM International Conference on Cracking in

Pavements, Dordrecht, Netherlands, June 2012, pages 453 to 463.

28. G.M. Rowe, L. Mohammad, B. Ahearn, M. Buncher, G. Reinke, W. Mogawer, N.

Gibson, T. Bennert, J.P. Planche, I. Al-Qadi, P. Marks, L. Tiarks-Martin, J. D’Angelo

and D. Anderson, “New Methods for Assessing Rheology Data such as ∆Tc and G-R

Parameter and Their Relationship to Performance of REOB in Asphalt Binders”,

FHWA Asphalt Binder Expert Task Group, USA, April 2017, pages 1 to 22.

29. TG1 MB3, “Method MB-3: Modified Rolling Thin Film Oven Test”, Asphalt

Academy, 2007, pages 69 to 70.

30. G.D. Airey, “State of the Art Report on Ageing Test Methods for Bituminous Pavement

Materials”, International Journal of Pavement Engineering, 4:3, July 2003, pages 165 to

176.

31. N. Saboo and P. Kumar, “Optimum Blending Requirements for EVA Modified

Binder”, International Journal of Pavement Research and Technology, 8:3, May 2015,

pages 172 to 178.

32. L.M.B. Costa, H.M.R.D. Silva, J.R.M. Oliveira, and S.R.M. Fernandes, “Incorporation

of Waste Plastic in Asphalt Binders to Improve their Performance in the Pavement,”

International Journal of Pavement Research and Technology, 6:4, May 2013, pages 457

to 464.

33. X. Lu and U. Isacsson, “Effect of Binder Rheology on the Low Temperature Cracking

of Asphalt Mixtures,” Road Materials and Pavement Design, 2:1, September 2001,

pages 29 to 47.

34. H.H. Kim and S.J. Lee, “Evaluation of rubber influence on the cracking resistance of

crumb rubber modified binders with wax additives,” Canadian Journal of Civil

Engineering, 43:4, February 2016, pages 326 to 333.

35. H. Fazaeli, A.A. Amini, F.M. Nejat and H.Behbahani, “Rheological properties of

bitumen modified with a combination of FT paraffin wax (Sasobit) and other

additives,” Journal of Civil Engineering and Management, 22:2, April 2013, pages 135

to 145.


36. G.L. Baumgardner, G.M. Rowe and G.H. Reinke, “BBR Rheological Evaluation of

Wax Modified Binders,” 7th

RILEM International Conference on Cracking in

Pavements, Dordrecht, Netherlands, June 2012, pages 901 to 910.

37. X. Lu and U. Isacsson, “Characterisation of SBS Polymer Modified Bitumens-

Comparison of Conventional Methods and Dynamic Mechanical Analyses,” Journal of

Testing and Evaluation, 25:4, July 1997, pages 383 to 390.

38. J.F. Masson, G. Polomark and P. Collins, “Glass Transitions and Amorphous Phases in

SBS Bitumen Blends,” Thermochimica Acta, 436:1-2, October 2005, pages 96 to 100.

39. J.F. Masson and G.M. Polomark, “Bitumen Microstructure by Modulated Dynamic

Scanning Calorimetry,” Thermochimica Acta, 374:2, 2001, pages 105 to 114.

40. M. Mouazen, A. Poulesquen and B. Vergnes, “Correlation between Thermal and

Rheological Studies to Characterize Behaviour of Bitumens,” Rheologica Acta, 50:2,

February 2011, pages 169 to 178.

41. M.O. Marasteanu, “Role of Bending Beam Rheometer Parameters in Thermal Stress

Calculations,” Transportation Research Record: Journal of the Transportation Research

Record Board, 1875:2, 2004, pages 9 to 13.

from crude oil to application: a low temperature and aging ...€¦ · 20/30, 50/70, 70/100 as well...

Documents