Low-temperature Performance Grade Research Articles

Performance Assessment of High Reclaimed Asphalt Pavement Asphalt Mixtures with Recycling Agents

The increased use of reclaimed asphalt pavement (RAP) in asphalt mixtures has promoted the use of recycling agents (RAs) to mitigate the effect of oxidized materials on the performance of asphalt mixtures. This laboratory-based study assesses the linear viscoelastic (LVE), cracking resistance, and permanent deformation properties of recycled asphalt mixtures containing RAs. The dosage levels used for this study were determined based on the manufacturer’s recommendation to restore the blended binder system’s low-temperature performance grade (PGL) to −22°C. The study found that blending a performance grade (PG) 64-22 virgin binder with RAs in high RAP mixtures can yield a comparable LVE response to high RAP mixtures designed using a softer binder (PG 58-28). Moreover, the study revealed that the cracking performance of high RAP mixtures could be improved without jeopardizing the rutting potential of the material by using RAs at dosage levels selected to yield a blended binder PGL of −22°C.

A Multi-Streamline Approach for Upcycling PET into a Biodiesel and Asphalt Modifier.

The non-degradable nature of petroleum-based plastics and the dependence on petroleum-based products in daily life and production are dilemmas of human development today. We hereby developed a plastic waste upcycling process to address these challenges. A multi-stream fraction strategy was developed to process poly (ethylene terephthalate) (PET) plastics into soluble and insoluble fractions. The soluble fraction was used as a sole carbon source for microbial fermentation to produce biodiesel precursor lipids with an appreciable bioconversion yield. The insoluble fraction containing fractionated polymers was used as the asphalt binder modifiers. The downsized PET additive improved the high-temperature performance of the asphalt binder by 1 performance grade (PG) without decreasing the low-temperature PG. Subsequent SEM imaging unveiled alterations in the micromorphology induced by PET incorporation. Further FTIR and 1H NMR analysis highlighted the aromatic groups of PET polymers as a crucial factor influencing performance enhancement. The results demonstrated the multi-stream fraction as a promising approach for repurposing plastic waste to produce biodiesel and modify asphalt. This approach holds the potential to tackle challenges in fuel supply and enhance infrastructure resilience to global warming.

Predicting flexural-creep stiffness in bending beam rheometer (BBR) experiments using advanced super learner machine learning techniques

BBR test is commonly used to assess the low-temperature performance grade (PG) of asphalt binders, with the flexural-creep stiffness being a critical parameter calculated through this test. However, it has notable limitations that demand attention. The significant amount of asphalt binder needed for test specimens increases costs and resource consumption. Additionally, the complex and time-consuming specimen preparation process hinders testing efficiency and introduces result variability, affecting the accuracy and reliability of PG determinations. In recent years, machine learning (ML) has emerged as a promising substitute for predicting various engineering values. In this study, the primary focus was on harnessing super learner (SL) techniques to predict the creep stiffness of asphalt binders. The SL approach combines multiple ML algorithms to enhance predictive accuracy and reduce individual model biases. Bagging, boosting, and stacking algorithms were employed in the construction of these prediction models. To conduct the investigation, data from 1350 samples sourced from the Long-Term Pavement Performance (LTPP) website were utilized to explore the influence of six crucial variables on the creep stiffness of asphalt binders. The proposed method demonstrated high accuracy, nearing 90% in the coefficient of determination. The Stacking model achieved a low Mean Absolute Percentage Error of 2.86% and robust Prediction Accuracy of 97.14% for randomly selected data points. Furthermore, the sensitivity analysis highlighted the significance of distinct input variables in influencing the creep stiffness of asphalt binders. Notably, the test temperature emerged as the most influential factor affecting creep stiffness, according to the conducted study

Evaluating the Effects of RA on the Rheological Properties and Aging Susceptibility of RAM Asphalt

Recycling agents (RAs) can mitigate the adverse effects of reclaimed asphalt pavement (RAP) on recycled asphalt, which can result in more RAP being added. To explore the effects of four RAs on recycled asphalt, this study used asphalt rheological performance experiments, including the bending beam rheometer (BBR) test, the dynamic shear rheological (DSR) test, and the indirect tensile asphalt cracking test (IDEAL-CT), to study the performance grade (PG), cracking resistance, and cracking susceptibility of recycled asphalt. In addition, an aging model for asphalt was used, and short-term and long-term aging sensitivities were evaluated according to this model. Results showed that US Soybean significantly enhanced the high-temperature and low-temperature performance grade (PGLT) and cracking resistance and reduced cracking sensitivity of the recycled asphalt. In addition, the short-term aging sensitivity was the lowest. It showed the best regeneration effect. However, the recycled asphalt with US Soybean showed the highest long-term aging sensitivity, suggesting that longer aging time results in poorer performance. Ingevity’s PG, cracking resistance, and cracking sensitivity are slightly lower than that of US Soybean, and Ingevity demonstrated the second lowest short-term aging sensitivity. However, its prolonged aging sensitivity was much lower than that of US Soybean. Asphalt and Wax Innovations and Georgia Pacific agents slightly improved recycled asphalt properties. The long-term aging sensitivity of recycled asphalt with four Ras was higher than that of recycled asphalt without Ras. These results indicated that the recycled asphalt’s performance with Ras worsened as aging time increased compared to the original recycled asphalt.

Influence of climate change on asphalt binder selection in China

ABSTRACT The impact of climate change on asphalt pavement infrastructure has become increasingly apparent. This paper investigated how climate change impacts the selection of asphalt binder for freeway pavement in China. The climate data predicted by the Global Climate Model were employed to select the appropriate performance grade for asphalt binder. The predicted air temperature converted pavement temperature, and performance grade distribution of the country was analysed. It is suggested that the performance grade of asphalt binder for freeways’ pavement should be determined based on ten years’ predicted climate data. This study concluded the following four major findings. Firstly, the selection of the appropriate asphalt binder performance grade needs to take into account the effects of future climate change. Secondly, the change in the standard deviation of temperature has a greater impact on the change in asphalt performance grade, as compared to the change in average air temperature. Thirdly, climate change affects the low-temperature performance grade more than the high-temperature performance grade in China. Finally, by 2050s, 15.2% of freeway asphalt pavement needs to upgrade high-temperature performance grade limit, and 17.3% of freeway asphalt pavement needs to upgrade to low-temperature performance grade limit.

Impact of Modified Post-Consumer Plastic (MPCP) Toner on Asphalt Binder Properties

The utilization of recycled plastics in asphalt pavements has become increasingly popular because of its potential benefits for the environment and economy. Prior studies have concentrated on incorporating high- and low-density polyethylene into asphalt mixtures as an additive to enhance their rheological and mechanical properties. Nevertheless, new techniques have surfaced for utilizing post-consumer plastics (PCP) that cannot otherwise be recycled. One example of PCP is toner, an electronic waste that is challenging to recycle but contains polymeric components such as styrene-acrylate, styrene-butadiene, and polyester, making it a promising candidate for modifying asphalt binders. This research explores the feasibility and potential of modified post-consumer plastic (MPCP), predominately composed of toner, as an additive to improve asphalt binder performance and address issues such as rutting and low-temperature cracking. The research employs Superpave performance grading, phase separation, frequency sweep, and multiple stress creep and recovery testing to assess the effectiveness of different MPCP dosages. The results indicate that MPCP-modified asphalt binders exhibit increased stiffness and viscosity proportional to the MPCP content, resulting in improved resistance to permanent deformation. However, a 20% MPCP dosage level significantly increases phase separation and adversely affects the low-temperature performance grade (PG), while a 10% MPCP dosage does not affect PG. The research recommends limiting MPCP dosage to 10% for optimal storage stability, increased stiffness, improved rutting resistance, and minimal changes in cracking resistance. Overall, this study provides insights on the effective use of MPCP in asphalt binders and the potential influence on the performance of asphalt concrete mixtures.

Benchmarking Recycled Binder Blends Using Statistical Analysis: A Case Study of Virginia and North Carolina

Recycling agents (RAs) are added to asphalt binder blends containing recycled materials to mitigate the negative effects of adding oxidized material to asphalt mixtures. Several methods exist to select a particular RA dosage to restore a specific Superpave performance parameter. However, the rheological similarities between the RA-modified systems and typical virgin binders across the complete range of temperatures remain to be ascertained. In this study, two RA dosage selection procedures, one aiming to restore high-temperature performance grade and the other aiming to restore low-temperature performance grade were statistically compared. Quality assurance datasets from Virginia and North Carolina were used to benchmark the typical virgin binder properties, and 17 recycled binder blends using constituent materials from the two states were studied with respect to Superpave binder properties. Both univariate and bivariate statistical analyses were applied to compare and contrast the rheological properties of these blends with the benchmarked virgin binder properties for the two states. Then, a statistical similarity analysis was done using the Mahalanobis distance to evaluate the rheological properties of these blends with those of the reference binders. The study found that both dosage selection procedures were successful in achieving rheological similarity at target-specific temperatures and for specific binder properties but might not necessarily yield similar properties at other temperatures. Finally, an example application is presented using statistical analysis to select an RA dosage that yields a rheological fingerprint more similar to that of virgin binder systems.

Effect of aged material properties on transverse crack performance with two-round field observations

This paper is aimed to validate the trend between thermal-related parameters and field-measured thermal cracking. Field thermal cracking is collected from four projects with twelve pavement sections. The material properties include creep compliance m-value and tensile strength of mixture, and asphalt low-temperature performance grade (PG). A lower value of m-value and tensile strength leads to a higher thermal cracking, while the low-temperature PG has the contrary trend. One or even several material properties cannot fully characterize field thermal cracking for all projects. Then the change of material properties, pavement structures, and climatic conditions are considered in three-dimensional finite element models (FEM). The aging effect of material properties attributes to the increase of thermal stress. The placement of chip seal could greatly reduce the aging rate, and the thicker pavement result in less thermal stress. Both material property and thickness are important design factors for thermal cracking resistance.

Rheological Characterization of Reclaimed Asphalt Binder Blended with The Neat And Sbs-pma Binders

Reusing reclaimed asphalt pavement material guarantees a substantial optimization of non-renewable material resources, emissions reduction, and decreasing landfill space, along with the economic benefits associated with saving the costs of purchasing and transporting new aggregate and asphalt binder for asphalt concrete mixture production. This study aims to investigate the influence of aged asphalt binder from reclaimed asphalt pavement on the virgin asphalt binder’s rheological properties. Therefore, different dosages of RAP binder (20%, 30%, and 40% by weight of the total mix) were blended with neat asphalt binder (40-50), penetration grade (P40), and SBS polymer asphalt (SBS-PMA) binder. Using both traditional and Superpave performance testing methods, the effects of RAP on the blend's consistency, viscosity, softening, elastic recovery, rutting (permanent deformation), fatigue cracking, and low temperature cracking were evaluated. The results revealed that the RAP binder decreased the penetration value of both neat and SBS-PMA binders. The neat asphalt binder’s viscosity and softening point increased with the increase in RAP content, whereas they decreased for SBS-PMA. The RAP binder decreases the SBS-PMA elastic recovery. where the neat asphalt experienced a little improvement in elastic recovery when blended with the RAP binder. The Superpave test results revealed that the RAP binder deteriorates the performance of the SBS-PMA binder at high, intermediate, and low testing temperatures. With the addition of 20%, 30%, and 40% RAP, the high-temperature PG grade of SBS-PMA blends decreased by 0.64%, 0.95%, and 1.10%, respectively, while the low-temperature PG grade increased by 23%, 31%, and 32%, respectively. In contrast, the RAP improves the neat asphalt blend's high-temperature performance grade and deteriorates intermediate and low-temperature performance grades. The addition of 20%, 30%, and 40% RAP increased the neat asphalt blends' high-temperature properties by 1.5%, 3.3%, and 4.5%, respectively. whereas the neat asphalt low-temperature PG grade increased by 5%, 11%, and 15% with the addition of 20%, 30%, and 40% RAP, respectively. In summary, the performance of virgin and RAP binder blends depends on the individual characteristics of the blended asphalt binders

Assessment of methods to select optimum doses of rejuvenators for asphalt mixtures with high RAP content

ABSTRACT This study explores different methodologies to select proper doses of three palm-oil-based rejuvenators to restore the properties of the effective binder present in asphalt mixtures with high Reclaimed Asphalt Pavement (RAP) content. Two commercial vegetable-based rejuvenators were also used as reference for comparison. The dose selection methods are based on penetration and softening point in unaged, short- and long-term aged states, and High Temperature Superpave Performance Grade (PGH) verified with Fatigue Low-Temperature Superpave Performance Grade (PGFL). In addition, a novel approach based on the thermodynamic properties of the recycled binder blends (i.e. mix of virgin binder, RAP binder and rejuvenator) quantified through the Surface Free Energy (SFE) measurements was also explored. In all cases, the optimum dose selection was determined by the amount of rejuvenator required to provide equivalent or better properties than the virgin binder in its unaged and aged conditions. The results suggest that the PGH approach verified with PGFL is the most appropriate method to determine the optimum rejuvenator dose. This methodology was initially validated by means of rheological and chemical testing conducted on the recycled binder blends at the selected dose in different ageing states.

Investigation on rheological characteristics of low-emissions crumb rubber modified asphalt

ABSTRACT Asphalt modified by microwave-treatment crumb rubber (CR-microwave) and that of deodorant-addition crumb rubber (CR-deodorant) have low unfavorable or detrimental emissions, but their high- and low-temperature performances have been insufficiently researched, potentially limiting their application and promotion. In order to investigate high-temperature performances of the two low-emissions crumb rubber modified asphalt (CRMA), viscosity, temperature ramp, creep and creep recovery and amplitude sweep tests were conducted using Brookfield Viscometer and dynamic shear rheometer (DSR). Also, low-temperature performances of CMRA were characterised by bending beam rheometer (BBR) tests. Results showed that deodorant-addition CR with a high dosage is not allowed considering asphalt workability, but microwave-treatment CR with various dosages can still meet workability requirements. Moreover, the introduction of microwave-treatment CR or deodorant-addition CR into asphalt improved high-temperature performances of asphalt, while the former had lower positive effects on high-temperature performance grades, elastic recovery and deformation resistance of asphalt. Furthermore, like common CRMA, the two low-emissions CRMA had different viscoelastic behaviour from styrene–butadiene-styrene copolymer (SBS) modified asphalt. Additionally, 18% CR-microwave or CR-deodorant can basically improve the low-temperature performance grades of asphalt. Comprehensively considering the workability and high- and low-temperature performances of the two low-emissions CRMA, 18% CR-microwave is recommended for low-emissions CRMA manufacture.

Effect of Oils on SBS Modified Asphalt: Rheological Characteristics and Oxidation Aging

This study focuses on the effect of oils on rheology and oxidation aging of Styrene-Butadiene-Styrene modified asphalt (SBSMA) in the long term, after reducing one low-temperature Performance Grade (PG) of SBSMA by incorporating oils. Two oils, including corn-based bio-oil and re-refined engine oil bottom (REOB), were selected to enhance the low-temperature performance of SBSMA. All samples were subjected to Rolling Thin Film Oven (RTFO) aging and 20-h as well as 40-h Pressure Aging Vessel (PAV20 and PAV40) aging, prior to multiple stress creep recovery (MSCR), frequency sweep and Flourier transform infrared spectroscopy (FTIR) scanning. A good high-temperature performance of oil/SBS modified asphalt blends was reflected in MSCR and PG results, meanwhile non-recoverable creep compliance (Jnr) and recovery (R) were found to share a highly correlated relationship during aging progress. In addition, Glover–Rowe (G–R) parameter and phase angle master curves suggest that the improvement of cracking property mainly came from the softening effect of oils. Adding oils into SBSMA was observed to increase oxidation kinetics, but the blends with oils still exhibited better anti-oxidation aging than the base binder, mainly due to the SBS addition. Bio-oil exhibited an effect of relieving age hardening susceptibility of SBSMA.

Low-temperature characterization of bitumen and correlation to chemical properties

A comprehensive understanding of the low-temperature performance of bitumen presents a crucial aspect in the durability of asphalt pavements. In order to capture these properties, current low-temperature testing by the bending beam rheometer (BBR) requires a relatively high amount of aged material, which is not always available. In recent studies, the complex shear modulus and phase angle acquired using a 4 mm geometry with the dynamic shear rheometer (DSR) have been used directly as a criterion for the lower performance grade of bitumen. The purpose of the presented study was to assess the application of the previously developed 4 mm DSR test method for material characterization at low temperatures and to develop a correlation between mechanical and chemical properties. BBR and DSR measurements were performed on 8non-modified and 4 polymer-modified binders. Fourier transform infrared (FTIR) spectroscopy and SARA fractionation were used to gather chemical information about the samples. A strong linear correlation (R2 = 0.93) between the results from BBR and DSR measurements could be observed, allowing an accurate assignment of the low-temperature performance grade for a majority of the investigated samples. Additionally, connections between the FTIR aging index, asphaltene content and the ratio of SARA fractions to the continuous lower performance grade and ΔTc were observed. This demonstrates the potential of chemical analysis methods to provide information about the low-temperature properties of bitumen.

Investigation of low-temperature cracking resistance of asphalt mixtures by conducting Disc-Shaped Compact Tension (DC(T)) and Semi-Circular Bend (SCB) tests

This research was focused to investigate the low-temperature cracking resistance of five plant produced SP12.5 surface course asphalt mixtures by conducting the Disc-Shaped Compact Tension (DC(T)), Semi-Circular Bend (SCB) and Bending Beam Rheometer (BBR) tests. The DC(T) and SCB testing were conducted at three temperatures, −18, −24 and −30℃, to characterize the cracking resistance and determine the mixture-based low-temperature Performance Grade (PG) of asphalt mixtures by using the suggested minimum threshold values of DC(T) fracture energy. Moreover, BBR testing was conducted on the recovered asphalt binders from the same asphalt mixtures. The analysis of tests results showed that the DC(T) and SCB fracture energies at three temperatures were statistically comparable and characterized the low-temperature cracking resistance similarly. Even though, the low temperature PG of the recovered asphalt binders were within the Superpave specifications, in some cases, they were mismatched with the mixture-based low-temperature PG. Dissimilar to the SCB fracture energies, the DC(T) fracture energies had better relationships with the low-temperature properties of the recovered asphalt binders. Considering the low-temperature PG of the recovered asphalt binders and the mixture-based low-temperature PG, the DC(T) and SCB tests are essentially needed to reliably evaluate the low-temperature cracking resistance of asphalt mixtures. Moreover, the relationships between the DC(T) fracture energies and the recovered asphalt binder properties revealed that there was a better correlation between the DC(T) fracture energies at three testing temperatures and the recovered asphalt binders’ temperatures corresponding to the stiffness value of 300 MPa.

Performance of Rejuvenated Asphalt and Mixtures with Waste Engine Oil Bottom and Liquid Styrene-Butadiene Rubber

To address the inadequate performance of rejuvenated asphalt when waste engine oil bottom (WEOB) is used as an asphalt rejuvenator, liquid styrene-butadiene rubber (liquid SBR) was used to enhance the performance of WEOB-rejuvenated asphalt. By testing the basic physical properties of asphalt and using the high- and low-temperature rheology, differential scanning calorimetry, Fourier infrared spectroscopy, and atomic force microscopy (AFM) tests, the index and microstructure changes of asphalt before and after aging and regeneration, from macrolevels and microlevels, were studied, along with the high- and low-temperature performance and water stability of the rejuvenated asphalt mixture. The WEOB decreased the glass transition temperature and low-temperature performance grade of aged asphalt and resulted in a significant effect on the recovery of penetration and softening point of aged asphalt; however, the recovery of low-temperature ductility was inadequate. Compared with WEOB, a rejuvenator comprising WEOB and liquid SBR (WEOB-S) further decreased the glass transition and continuous grading temperatures of aged asphalt, improved its low-temperature performance, and significantly influenced its ductility recovery. The AFM test showed that WEOB-S effectively dispersed the agglomerated bee-like wax crystals or macromolecular asphaltene structures in the aged asphalt, decreased the number and crests of the bee-like structures, and improved the microscopic uniformity, thus obtaining better macroscopic physical properties. Both WEOB and WEOB-S improved the low-temperature performance and water stability of rejuvenated asphalt mixtures; however, WEOB-S was more effective.

On the use of empirical phase angle limits for the grading of asphalt binder

• Asphalt phase angles can be measured most precisely and rapidly. • Limiting phase angle temperatures correlate with DENT properties. • Limiting phase angle temperatures correlate with EBBR properties. • Divergent behavior is seen for softer binders where correlations weaken. In recent years, Ontario paving contracts have specified asphalt binders based on limits for: (1) critical crack tip opening displacements (CTOD) obtained in the double-edge-notched tension (DENT) test, (2) limiting low temperature performance grades (LLTPG) obtained in the extended bending beam rheometer test (EBBR), and (3) EBBR grade losses, in addition to (4) regular American Association of State and Highway Transportation Officials (AASHTO) M320 criteria. While the enhanced performance measures are expected to provide significant improvements in pavement performance, both DENT and EBBR protocols are cumbersome. A total of 371 sets of binder test results are used to assess if CTOD, EBBR LLTPG and grade losses can be replaced with limiting phase angle temperatures T 30° and T 45° , in an effort to make the binder specification more practical. The CTOD, LLTPG and grade loss correlate strongly with phase angle but variation for softer grades were found to be significant, which likely relates to differences in aging mechanisms in the laboratory and service (chemistry and/or thermal history, exudation of oils). A phase angle specification for the control of pavement cracking deserves further consideration for its accuracy, sensitivity, precision and thus usefulness.

Low-temperature thermal cracking performance of waterborne epoxy asphalt emulsion mastic based on bending beam rheometer (BBR)

This research experimentally investigated the low-temperature thermal cracking performance of waterborne epoxy asphalt emulsion (WEA) mastic. A total of sixteen WEA mastics were prepared by utilizing two mineral fillers (Portland cement as an active filler and limestone dust as an inert filler) and two WEAs (anionic and cationic emulsions). They were then subjected to the bending beam rheometer (BBR) test. Based on the test results, four parameters, creep stiffness at loading time of 60 s, S(60 s), creep rate at loading time of 60 s, m(60 s), m(60 s)/S(60 s), and the difference in critical low temperature performance grade limiting temperatures, ΔTc, were calculated to evaluate WEA mastics’ low-temperature creep and relaxation properties. The results showed that mineral fillers diminished the susceptibility of WEA material to stiffness growth with testing temperature drop. The charge type of WEA emulsion showed a significant effect on the low-temperature performance grade of WEA-cement mastic. The ΔTc value of anionic WEA-cement mastic was 10℃ more than that of cationic WEA-cement mastic. The creep stiffness master curves fitted by Christensen-Anderson-Marasteanu (CAM) model could better understand the low-temperature creep characteristics of WEA mastics in a wide range of time domains.

Investigating the properties of rejuvenated asphalt with the modified rejuvenator prepared by waste cooking oil and waste tire crumb rubber

WROB modified rejuvenator prepared by waste tire crumb rubber (WTCR) and waste cooking oil (WCO) had tremendous potentiality in reactivating and modifying the aged asphalt. The compatibility, high and low-temperature rheological properties, anti-rutting, aging and fatigue resistance properties were assessed by dynamic shear rheometer (DSR), bending beam rheometer (BBR) and multiple stress creep and recovery (MSCR) tests. The Fourier transform infrared spectrometer (FTIR) test results revealed that WTCR contained in WROB modified rejuvenator could regenerate the aged asphalt. The Cole-Cole curves showed that the WTCR has an active function in boosting compatibility. Moreover, the MSCR test results indicated that the WTCR had a functional effect on ameliorating the anti-rutting performance and reducing sensitivity to rutting of the rejuvenated asphalt. The indexes of anti-aging and G*·sin (δ) values respectively showed the contribution of WTCR to anti-aging performance and fatigue resistance of the rejuvenated asphalt. With 8.5% WROB modified rejuvenator, the high and low-temperature performance grade of the aged asphalt was recovered from 82–16 to 76–28. Besides, all the properties of WROB60 rejuvenated asphalt were outstanding. The properties of WROB regenerated asphalt were slightly decreased when the content of WTCR contained in the modified rejuvenator was greater than 60.

Preliminary study of modified asphalt binders with thermoplastics: The Rheology properties and interfacial adhesion between thermoplastics and asphalt binder

In recent decades, polymer-modified asphalt materials have been used in response to increased traffic on the roads. The main objective of this paper is to explore the modification effect of thermoplastics on asphalt binders and investigate the effectiveness of maleic anhydride in improving interfacial adhesion. Three different thermoplastics were used with a dosage of 4 wt%. and a co-reactant maleic anhydride was added with a content of 2 wt% by weight of the binder. The thermoplastics showed a great improvement on high-temperature performance grade (PG) and a slight decrease on low-temperature PG. In addition, the usage of maleic anhydride enhanced the high performance PG on all plastic modified binders. With the addition of maleic anhydride, the binders increased a few degrees of higher temperature, indicating an improvement in compatibility. The compatibility improvement may be related to form a copolymer where maleic anhydride modified with different asphalt components. With the addition of maleic anhydride, the Jnr decreased and the percent recovery increased, which showed a better interaction between plastic and asphalt binders. High-temperature PG results in Unified Performance Tests by incremental Method (UPTiM) were strongly connected with Jnr3.2 in Multiple Stress Creep Recovery test with a power fit trend, where its R2 was 0.97. Based upon results obtained, it can be concluded that the performance of the resulting asphalt can be improved when maleic anhydride was used to treat the added thermoplastics.

Experimental, analytical, and analogical study of the effect of RAP extracted binder on rheology of polymer modified binder

This study attempts to scrutinise the effect of RAP on Performance Grade (PG), fatigue, and low temperature performance of polymer modified binder (PMB40). Furthermore, analytical, and analogical modelling was conducted. RAP from two sources was blended with PMB40 in proportions of 15%, 25%, and 40%. Thereafter, PG isochronal temperature sweeps, isothermal frequency sweeps and bending beam rheometer (BBR) testing was conducted. RAP sources affected both high and low temperature PG of PMB40. Viscoelastic transition temperature (TVET ) increased on inclusion of RAP thereby compromising fatigue performance. Based on difference in critical temperatures (ΔTc ), inclusion of RAP compromised the low temperature performance. Stiffness master curves (S(t)) illustrated an enhancement in stiffness on RAP inclusion whereas relaxation modulus master curves (E(t)) depicted a decrease in rate of decay of E(t) thereby compromising the low temperature stress relaxation potential. Both 2S2P1D and Huet models illustrated a reasonably good fit for various RAP blends.