Aged Binder Research Articles

Feasibility of Carnauba Wax Rejuvenators for Asphalt Concrete with Vacuum Tower Bottom Binder

This study addresses the need for effective rejuvenators in asphalt concrete mixtures containing Vacuum Tower Bottom (VB) binder, a by-product of petroleum refining. We investigated the use of a softening rejuvenator, comprising Carnauba (5.5%), Soybean oil (3%), water (81%), surfactant (1.5%), and additive (3%) from a Korean refining company, to mitigate the brittleness of VB binder. Laboratory experiments were conducted to compare the performance of the modified binder with the original hardened binder. The results showed that adding the rejuvenator improved the properties of the VB binder. Optimal asphalt grades were achieved with a 2% content of the softening additive in the VB binder. The rejuvenator enhanced moisture resistance, leading to settlements comparable to the control asphalt. Settlements after 20,000 load repetitions were 11.49 mm for the modified mixture, which were slightly better than the control material at 12.44 mm. Moisture stripping points occurred at around 16,000 cycles for the modified mixture, while the control material experienced them at approximately 13,000 cycles. Under freeze-thaw cycles, the modified mixture exhibited enhanced durability compared to the control mixture. The control mixture experienced a significant increase in rutting value of approximately 59.7% (from 12.4 mm to 19.7 mm), while the modified mixture showed a relatively lower increase of approximately 37.4% (from 11.5 mm to 15.8 mm). Additionally, the modified VB mixture demonstrated approximately 7.8% higher dynamic modulus at lower temperatures, indicating improved mechanical properties. It also displayed superior fatigue crack resistance, with a fatigue life of 18,385 cycles compared to 15,775 cycles for the control asphalt. Field results confirmed that the VB asphalt mixture with the rejuvenator achieved comparable site compactness to the control mixture, indicating successful compaction performance. These findings highlight the rejuvenator’s efficacy in mitigating binder stiffening and restoring the original state of aged asphalt binders.

Study on the effect of different environmental factors on the aging gradient of asphalt binder based on field aging test

ABSTRACT Aging of asphalt binder is a complex natural phenomenon with significant differences under the effect of different environmental factors. The accelerated aging method commonly used in the laboratory is difficult to reproduce the field aging of asphalt binder. The purpose of this study is to reveal the effect of environmental factors on the aging gradient of asphalt binder. For this reason, a layered dissolution-peeling method was developed to recycle asphalt binder films. The gradient behaviour of field-aged asphalt binder was analysed based on rheological parameters and chemical functional groups. The results showed that the layered dissolution-peeling method achieved separation of asphalt binder at 0.1 mm level. Ultraviolet light severely contributed to the distinct aging gradient of field-aged asphalt binder. The carbonyl index of field-aged asphalt binder at 0–0.32 mm was approximately 1.73 times higher than that at 0.32–0.64 mm, 1.90 times higher than that at 0.64–0.96 mm and 2.24 times higher than that at 0.96–1.28 mm. To significantly characterise the aging behaviour of asphalt binder, the film thickness in the accelerated aging simulation test should not be more than 1 mm. The findings of the study serve as a valuable reference for accurate prediction and targeted prevention for asphalt pavements.

The performance evaluation of extracted asphalt binder from dry process produced rubber modified asphalt mixture

Limited research studied the influence of rubber on asphalt binder in the dry process rubberized asphalt mixture. By using the extraction procedure, the asphalt binder interacted with rubber could be obtained and assessed. The goal of the research is to evaluate the accurate characteristics of asphalt binder from dry process rubberized asphalt mixture and determine the interacted rubber percentage in dry process rubberized asphalt mixture. Four extracted and two laboratory prepared asphalt binders were compared. The rheological performance, creep and recovery, and low temperature characteristics of different were evaluated with the dynamic shear rheology, multiple stress creep and recovery, and asphalt binder cracking device tests, respectively. The rubber modification and aged binder from the RAP enhanced the high temperature characteristics of the asphalt binder. Rubber modification increased the elastic property and deformation resistance of the asphalt binder and decreased the stress sensitivity of the asphalt binder. The coupling effect of aged asphalt binder and rubber addition enhanced the permanent deformation resistance of the asphalt binder to sustain heavy stress load. The aged binder from RAP deteriorated the low temperature characteristics of the extracted asphalt binder. The base asphalt binder with rubber had a better ability to dissipate the stress in the asphalt binder due to the decrease in temperature. The interacted rubber percentage was estimated by comparing the rutting parameter and percent recovery, and the estimation results based on the DSR and MSCR test had a good correlation. The interacted rubber percentage in the two types of rubber modified mixtures are 61.9% and 57.4%, respectively.

Microscopic R-curve simulation study of asphalt material fracture

Cracks can significantly influence the service life of an asphalt pavement. To study the microcracking behavior of asphalt materials, this paper utilized molecular dynamics simulation methods to simulate the tensile fracture process of asphalt materials at the microscopic level and described the fracture behavior using R-curve. Two experimental factors, temperature and loading rate, were selected to simulate the tensile fracture of virgin asphalt binder, aged asphalt binder, and SBS modified asphalt binder, and Microeconomic R-curve were constructed based on the fracture displacement and cumulative fracture energy of asphalt materials. Meanwhile, fracture energy, cohesive energy, and energy rate were used to evaluate the fracture behavior of asphalt materials. The results indicated that the micro-R curve simulated by molecular dynamics can well describe the tensile fracture behavior of asphalt. Among the fracture indicators, fracture energy and energy rate were significantly affected by the type of asphalt, while cohesive energy was significantly affected by the loading rate.

An atomistic model of aged asphalt guided by the oxidation chemistry of benzylic carbon with application to asphalt rejuvenated with a triglyceride

Waste cooking oil (WCO) shows promise for restoring physical properties of aged asphalt binder to enable pavement recycling. Its use as a rejuvenator lessens the environmental burden on land fills with its disposal. In this study, we report our initial development of an aged asphalt model and the computational investigation of the effect of triglycerides, the main component of WCO, on the viscosity, self-diffusion, and microstructural properties of aged asphalt at 1 atm and 404 K. The fundamental research question in this work involves understanding the underlying mechanism(s) by which WCO rejuvenates aged asphalt binder. A central feature of this aged asphalt model is consideration of oxidation chemistry and reported functional group concentrations since properties like viscosity are known to be related to the amounts of moieties such as ketones and sulfoxides. Model oxidation compounds include proposed representative asphalt structures based on Peterson’s dual reaction pathways, leading to polycyclic aromatic hydrocarbon molecules resulting from fast phase aromatization and multiple species from a slow phase degradation of benzylic hydroperoxide intermediates. The new model takes into account the observed product distribution of aryl alcohols and aryl ketones based on findings for cumene oxidation in the literature. Other oxygen-containing functional groups, such as anhydrides, carboxylic acids, and polynuclear aromatics, have been incorporated to account for the critical physical characteristics of aged asphalt. By extending the molecular basis set of asphalt components, we can now construct more realistic asphalt models to represent varying SARA (Saturates, Aromatics, Resins, Asphaltents) content, different oxidation levels and functional group composition. Virtual representations of the molecules in the basis set were created and molecular dynamics simulations of the aged asphalt model conducted. Results with aged asphalt basis set provided good agreement with reported physical properties. With the developed aged asphalt model, our molecular dynamics simulations reveal that triglyceride (tristearin) has preferential interactions with asphaltene molecules. On addition of 10 wt% triglyceride to aged asphalt, the asphaltene-asphaltene interaction was most significantly affected. The radial distribution functional analysis revealed that the asphaltene-asphaltene nearest neighbor distance increased from 4.0 Å to 7.5 Å. Thus, adding triglyceride to aged asphalt helps to reduce the aggregation of asphalt components and as such promotes a decrease in viscosity of the aged asphalt, from 83 cP to 69 cP. In addition, the asphaltene components have larger self-diffusion coefficients upon the addition of triglyceride, changing from 3.57 × 10−8 cm2/s in the aged asphalt to 1.41 × 10−7 cm2/s in the triglyceride/aged asphalt mixture. Those findings are consistent with the observed effectiveness of utilizing waste cooking oil to rejuvenate aged asphalt.

Study on accelerated aging rate of asphalt binder under multi-factors coupling conditions

The aging behavior of asphalt binder in service is complex. The accelerated aging methods commonly used in the laboratory are difficult to reproduce the aging behavior of asphalt binder in service. The purpose of this study is to develop a method for predicting the properties of asphalt binder in service. First, a multi-factor accelerating (MFA) aging method was developed to accelerate the aging of asphalt binder. Multi-scale characterization and correlation analysis were conducted on the MFA-aged asphalt binder. Then, the evaluation index of MFA aging was defined, which was used to establish the prediction equation for asphalt binder aging. Finally, the time correlation between field aging, pressure aging vessel (PAV) aging and MFA aging was constructed separately. The results show that accelerated aging of asphalt binder at atmospheric pressure and service temperature can be achieved by the coupled effect of temperature, ultraviolet light and rain. After 5-day MFA aging, the Glover-Rowe (G-R) parameter, an index for evaluating the cracking resistance of asphalt binder, was increased by 308%. The carbonyl index, an index for evaluating the content of chemical functional groups of asphalt binder, was increased by 67%. The correlation between the G-R parameter and the carbonyl index was linear, and the goodness-of-fit was greater than 0.9. The carbonyl index as a key chemical index may reflect the macroscopic properties of asphalt binder. The prediction equation for aging was established based on the carbonyl index of field-aged asphalt binder in Beijing, with reliability greater than 0.98. PAV aging for 20 h was equivalent to 1.35 years of asphalt binder service in Beijing. MFA aging method can better predict the aging time in the field. The prediction accuracy was 97.2%, which was 4.9% higher compared to that of PAV aging. MFA aging for 5 days was equivalent to about 2 years of asphalt binder service in Beijing.

Rheological performance of bitumen mixed with laboratory simulated polymerized RAP binders

Researchers have mostly used three artificial aging techniques, namely pressure aging vessel (PAV) binder aging, compacted mix aging (CMA), and loose mix aging (LMA) to simulate recycled asphalt pavement (RAP) binder in the laboratory. RAP binder (RAPB) simulated using different techniques will differ in characteristics and may affect the performance of the base binder differently. Which may affect the parameters used for blending and recycling, such as the selection of base binder, rejuvenator dosage, etc. Therefore, in this study, three RAP binders, namely RAPB-P, RAPB-C, and RAPB-L, were simulated from a polymer modified binder (PMB) with 3.5% SBS content, using PAV aging (100 °C, 20 hrs, 2.1 MPa), CMA (85 °C, 5 days) and LMA (85 °C, 8 days), respectively. These polymerized RAPBs were added to an unmodified binder (AC 30) at three proportions: 15 %, 25 %, and 40 %. These RAPB and AC 30 blends were characterized in terms of their dynamic viscosity, mixing and compaction temperature, and high temperature performance grade (PG). Superpave rutting factor (|G*|/sin δ) and multiple stress creep and recovery (MSCR) test parameters were used to evaluate the rutting performance of the RAPB blended AC 30 binders. Further, resistance to yielding and elastic recovery values were evaluated using the binder yield energy test (BYET). The test results suggested that all three RAP binders affect the performance of the AC 30 binder differently, which was also confirmed by statistical analysis using one-way ANOVA. From MSCR and BYET test results, it may be stated that RAP binder simulated from standard PAV aging may mislead in predicting the high and intermediate temperature performance of AC 30 binder with RAPB. Overall, the present study is helpful for asphalt researchers and practitioners to understand how the selection of different defined aging strategies affects the performance of aged recycled PMB with unmodified base binder.

Investigating the cracking performance of asphalt mixture containing RAP using different cracking indices

Due to environmental benefits and economic issues, the use of reclaimed asphalt pavement (RAP) in asphalt mixtures has become a necessity. However, mixtures containing RAP have poor performance against cracking at different temperatures due to excessive stiffness and aged binder. Therefore, evaluating the cracking performance of RAP is of great importance. In this research, the semicircular bending (SCB) test was used to evaluate fracture characteristics. For this purpose, the indicators of peak load (Pmax), fracture energy until failure (FEUF), fracture energy after failure (FEAF), fracture strain tolerance (FST), and power (P) are used. The SCB test was performed at 25 °C and − 12 °C, and all indicators were calculated at intermediate and low temperatures. Three different percentages of RAP (0%, 50%, and 100%) were used. Also, three different rejuvenators, Waste Engine Oil (WEO), Oleic Acid (OA), and Vacuum Bottom (VB), were used with four different doses. Then recycled high-density polyethylene (r-HDPE) in four different amounts (0%, 3%, 5%, and 7%) was used separately and in combination with rejuvenators to prepare the samples. Also, to expand the application of SCB tests worldwide, and due to the availability and simplicity of the Marshall device, non-standard samples with a diameter of 100 mm made by this device were used. Experimental results showed that the use of a rejuvenator alone, as well as in combination with the recycled polymer, could improve the cracking resistance of asphalt mixtures at medium and low temperatures. Results showed that VB performed best at 25 °C and OA at − 12 °C. An increase of 53% was seen in the FST index for the VB rejuvenator and 62% in the OA rejuvenator. Also, VB (at 25 °C) and OA (at −12 °C) improved crack propagation resistance by 62% and 94%, respectively. To evaluate the results, statistical analyzes were used. The statistical results showed that using the Marshall compaction device to make the samples has a suitable accuracy. In addition, the statistical results showed that the fracture behavior of mixtures containing RAP at a temperature of 25 °C differs from a temperature of − 12 °C.

Study on effect of thermal, oxidative and ultraviolet coupled aging on rheological properties of asphalt binder and their contribution rates

ABSTRACT This paper aims to investigate the effect of different environmental conditions on the aging properties of virgin asphalt binder and evaluate the magnitude of aging on asphalt binder under different environmental conditions. The effect of thermal, oxidative and ultraviolet aging on the rutting resistance, fatigue resistance and cracking resistance of virgin asphalt binder was characterised based on rheological parameters. The contribution rate of different environmental factors to the aging of asphalt binder was quantitatively analysed. Results showed that high temperature repaired cracks in the asphalt binder caused by ultraviolet aging. The single aging factor of heat, oxygen and light had little effect on the rheological properties of asphalt binder. High temperature and oxygen would accelerate the aging effect of the asphalt binder aging process. Thermal–oxidative–UV-coupled aging had a more pronounced effect on the aging of asphalt binder than thermal–oxidative aging. The fatigue resistance of asphalt binder is more sensitive to the response of aging. The contribution rates of thermal–UV aging, UV–oxidative aging and thermal–oxidative aging were all greater than the sum of the contribution rates of the two corresponding single factors. The aging of asphalt binder was mainly due to thermal–oxidative aging when the aging temperature exceeded 80°C.

Retarding thermal-oxidative aging of anhydride-cured epoxy asphalt binder and mixture by incorporating antioxidant Irganox 1010

ABSTRACT This research focused on the stabilisation of anhydride-cured epoxy asphalt (EA) over thermal-oxidative aging. EA binders with graduated Irganox 1010 antioxidant contents at 0, 0.3, 0.6, 0.9, and 1.2 wt% were prepared and then subjected to accelerated oven-conditioning aging at 85 and 100°C. The thermal stability, viscosity, mechanical parameters, and chemical structure of EA containing Irganox 1010 were evaluated during aging. The results showed that Irganox 1010 contributed to enhanced thermal stability, higher initial viscosity, and longer allowable construction time for EA. The 0.3–0.9 wt% Irganox 1010 had good compatibility with EA without weakening performance. During aging, Irganox 1010 effectively restrained degradation of the EA binder’s mechanical properties and the EA mixture’s low-temperature deformation. The variations of functional groups indicate that Irganox 1010 prominently restrained the oxidation of the asphalt phase and lightly affected the post-curing of the resin phase. There was a strong correlation between decreasing rate of bending strain of the mixture and increasing rate of sulfoxide in the binder. The mutual synergistic effect of resin and antioxidant improves the oxidation resistance of asphalt. Considering the aging improvement and economic cost, it is recommended to use 0.6 wt% Irganox 1010 as an antioxidant for anhydride-cured EA. Highlights Epoxy asphalt (EA) binder and mixtures incorporating antioxidant Irganox 1010 were analysed. Irganox 1010 plays a crucial role in aging protection effect of EA binder and mixture. Irganox 1010 antioxidant prominently restrains the oxidation of the asphalt phase and lightly affects the post-curing of the resin phase. There was a strong correlation between the bending strain of mixture and sulfoxide of binder. Addition of 0.6 wt% Irganox 1010 is recommended as an antioxidant for EA materials.

Investigating the Addition of Organomontmorillonite Nanoclay and Its Effects on the Performance of Asphalt Binder

Asphalt binder aging is a complex phenomenon that plays an essential role in reducing flexible pavement serviceability. The aging resistance of asphalt binder can be enhanced through the binder modification. This research investigates the impact of aging on unmodified and organo-montmorillonite (OMMT) nanoclay modified asphalt binders. In this study, laboratory aging is carried out for asphalt binders modified with two types of OMMT nanoclays at different dosages (2% and 4% by weight of the binder). The asphalt binders are subjected to short-term and long-term aging using a rolling thin-film oven and pressure aging vessel equipment. Rheological properties of the aged and unaged binders are determined using a dynamic shear rheometer. In addition, storage stability, full performance grading, and rutting resistance of the binders are evaluated and compared. Aging indices were calculated to investigate the aging behavior of the unmodified and modified binders. The results showed that the montmorillonite nanoclay-modified asphalts had improved resistance to aging compared with the unmodified binder.

Rheological, Mechanical, Microscopic, and Chemical Characterization of Asphalt Binders at Extended Aging Levels

This study aims to connect asphalt binder mechanical properties to their dynamic microscopic morphology and chemical indices to provide a more thorough and fundamental picture of aging and cracking phenomena. Unmodified and modified asphalt binders were aged to five levels for a comprehensive representation of the asphalt binder service life. Rheological indices used covered linear viscoelastic cracking indicators and nonlinear parameters including fatigue life obtained by the linear amplitude sweep test. A recently validated asphalt binder cracking test, the poker chip test, was used to provide new insight into the mechanical performance of asphalt binders as they stretch into the nonlinear regime and experience cavitation damage. Rheological and mechanical properties were compared to static surface topography from atomic force microscopy (AFM) and time-sensitive asphalt binder microstructure based on electron beam loading using an environmental scanning electron microscope (ESEM). Results indicated that the parameters based on linear viscoelastic analysis and fatigue life derived from the linear amplitude sweep (LAS) test are not adequate to delineate the evolution of asphalt binder behavior with aging among different asphalt binders, due to poor ranking based on known phenomena. However, it was confirmed that the poker chip test was sensitive to longer aging cycles and could capture the total degradation of the asphalt binder’s ductility for both modified and unmodified asphalt binders. The consistency between ESEM and AFM was ensured by observing static surface structures; however, quantification of the fibril formation in ESEM images was the most critical morphological observation when it came poker chip results, because both sharing similar deformation mechanisms. Chemical characterization using Fourier transform infrared spectroscopy was also able to capture asphalt binder aging well, and could be best related to the strength of the asphalt binder. Overall, it was established that the surface microstructure has some relationship to mechanical properties, but not a definitive one, and that using ESEM as an energy absorption indicator was most similar to the comprehensive results from mechanical and chemical testing.

Investigation of rejuvenation mechanisms of reclaimed asphalt rubber pavement through mortar tests

ABSTRACT Conventional rejuvenation methods recover the rheological properties of aged bitumen by adding rejuvenators to supplement the content of light fractions of bitumen. However, these methods cannot fully restore the microstructure and advantages of aged asphalt rubber (AR) binder due to the dissolution of rubber particles. Aiming at discovering a more suitable rejuvenation strategy for reclaimed asphalt rubber pavement (RARP), this study investigates the rejuvenation mechanisms of RARP through a series of chemical and rheological tests at the mortar level. A chemistry-based method was proposed to estimate the rubber dissolution in RARP mortar. AR mortars containing 40% of RARP mortar (RARP40%) were prepared. Three rejuvenation schemes were adopted for RARP40%, namely recovering the light fractions, supplementing the swelling rubber content, and both recovering and supplementing, respectively. The results indicate that adding rejuvenator only can effectively soften the aged RARP binder but it fails to slow down the rheological evolution of RARP40% mortar in the secondary aging. The incorporation of AR binder with extra rubber content notably improved the aging resistance but significantly compromised the workability of RARP40% mortar. The compound rejuvenation scheme was the optimum solution that balanced the rejuvenation effectiveness, aging resistance and workability.

Influence of epoxy resin polymer on recycled asphalt binder properties

Utilization of high-performance pavement materials with a high reclaimed asphalt pavement (RAP) content is gradually gaining importance given the impetus of green environmental policies. Epoxy resin polymer (EP) can greatly enhance the reuse of RAP materials in asphalt mixture. The influence of EP on the properties of aged asphalt binder was investigated wherein mechanical and chemical properties, and the micro-morphology of binders composed of aged asphalt binder and EP were also evaluated. EP significantly improved tensile, high-temperature, low-temperature, and fatigue properties of aged asphalt binder, and simultaneously reduced concentration of sulfoxide and carbonyl of aged asphalt binder. Increasing EP content reduced the impact of asphalt ageing degree on mechanical properties, micro-morphology, and chemical composition. Furthermore, the construction allowance time of the binder was increased with increasing EP content. At 40% EP content, an effective network structure was formed in the aged asphalt binder, leading to higher tensile elongation, high-temperature rheological properties, and fatigue life as compared to virgin asphalt binder. Meanwhile, low-temperature modulus and sulfoxide and carbonyl concentrations were lower than those of virgin asphalt binder. For application, a recommended EP content of 40% is suggested.

A portable microfluidic device integrated with electrochemical sensing platform for detection of multiple binders in ancient wall paintings

The aging of the proteinaceous binders will cause the cultural relics to suffer from diseases such as flaking, cracks, and even peeling. Identifying the type of binders in a timely manner is conducive to restore diseased cultural relics. High-throughput and portable detection system are of great significance for researching cultural relic materials on the archaeological site. Therefore, in this work, a portable electrochemical microfluidic device for the simultaneous detection of casein, ovalbumin, and peach gum binders was developed. The proposed electrochemical immunosensor technology integrated with microfluidic device achieve the goals of miniaturization, portability and reagent-saving. For casein, ovalbumin and peach gum, excellent performance was obtained in terms of their limits of detection (LOD) at 0.237, 0.507, and 0.403 ng mL−1 (S/N = 3), respectively. In addition, the microfluidic sensing platform exhibited acceptable anti-interference ability, stability, and storage capacity. In order to evaluate the practical application value, the proposed microfluidic sensing device was applied for detecting eight archaeological samples from different historic sites. This work demonstrates great potential for high-throughput, portable detection of cultural relic proteinaceous binder materials.

The Application of Bio-Emulsion from Soybean Oil Partially Epoxidized as a Maintenance Technique for Flexible Pavements

Abstract An increase in the use of biomaterials has been noted in recent years because of several impacts caused by human activities, especially for engineering and paving industry benefits. Several renewable resources, such as a nonfood source of soybean oil, have been successfully tested on modification of asphalt binders. However, their impact on the pavement life cycle is still unknown. Thereby, the objective of this research was to investigate soybean oil as a new, green supply for the maintenance of flexible pavements. The experimental plan consisted of the construction of field test sections through the application of sub-epoxidized soybean oil (SESO) over a flexible pavement surface. Rates of 0.1 and 0.3 L/m2 were chosen, and the main tests intended for study were functional procedures including the British pendulum and sand patch tests on the pavement surface, which were complemented with the indirect tensile strength test for mechanical analysis. The change in the chemical composition of the recovered binder was analyzed by thin layer chromatography and Fourier-transform infrared spectroscopy. The rheological properties were analyzed by frequency sweep, linear amplitude sweep, and multiple stress creep and recovery, and the tests were carried out with a dynamic shear rheometer. The effects of the SESO bio-emulsion demonstrated a rejuvenating activity on the properties of the aged binder, with mechanical and rheological improvements for both analyzed rates. A further investigation is indicated to evaluate the influence of time on the modification studied in this work. Such testing could ensure the use of SESO bio-emulsion as an environmentally friendly alternative for the maintenance of flexible pavements.

Multiple Stress Creep Recovery Test to Differentiate Polymer Modified Bitumen at High Temperature

Abstract The constant demand for high-performing and more reliable roads has led to an increasing use of complex bituminous binders such as polymer-modified bituminous binders, which has become a widespread practice for asphalt pavement. As a result, specification and testing have evolved to better distinguish between quality materials. In recent years, more focus has been devoted to better evaluating the rutting resistance of bituminous binders. The multiple stress creep recovery (MSCR) test has gained popularity over the last decade, especially for polymer-modified binders, bringing more advantages in discriminating amongst quality binders such as polymer-modified bitumen. Within the International Union of Laboratories and Experts in Construction Materials, Systems and Structures technical committee 272, Phase and Interphase of Behavior of Innovative bituminous Materials, and its TG1 task group, several binders were thoroughly evaluated, including two non-modified and two polymer-modified bituminous binders, under various testing conditions to address the high-temperature behavior. Five laboratories performed MSCR on short-term aged binders after performing the rolling thin film oven test, in the same temperature conditions for all binders. Despite the limited data set, the variability between laboratories was reasonable. The MSCR results were compared with softening point temperature, high-temperature performance grade criteria, |G*| / sinδ, and equi-modulus temperature. MSCR was able to distinguish between complex binders better as compared with conventional parameters. It generates multiple useful parameters, amongst which percent recovery and non-recoverable creep compliance are the most relevant. This paper presents the analysis of MSCR results and comparison with other test methods.

Evaluation of Aging Evolution of Olive Pomace–Modified Asphalt Binders under Natural Weather Aging Conditions

Abstract The natural weather aging test (NWAT) for asphalt binders is an essential benchmark aging test used to investigate the aging evolution of asphalt binders under actual weather conditions. This study assessed the aging rates of olive pomace–modified asphalt binders and the control neat binder under NWAT. Instead of aging days, weather factors were proposed as metrics to correlate with the aging evolution of the rheological properties of asphalt binders. The test results showed that the olive pulp–rich fraction-modified asphalt binders after the rolling thin-film oven (RTFO) test had lower aging susceptibility than the RTFO-aged control binder. The RTFO-aged binders exhibited lower aging rates than the corresponding unaged asphalt binders under NWAT. The sums of weather indexes such as the sum of the daily maximum ultraviolet index are rational field metrics to correlate with the rheological aging properties of natural weather–aged asphalt binders. Caution shall be taken when using aging days to interpret the aging rates of asphalt binders under NWAT.

Laboratory evaluation on the aging susceptibility of reclaimed asphalt bitumen containing low-viscosity binder and cooking oil waste

This study investigates the use of cooking oil waste (COW) and low-viscosity binder (LVB) to improve the performance of reclaimed asphalt pavement (RAP) binders and promote the consumption of by-product materials. The aging resistance capacity of experimentally aged asphalt binders with COW as rejuvenators and recently synthesized high-penetration asphalt binders was evaluated using the Rolling Thin Film Oven Test (RTFOT) and the Pressure Aging Vessel (PAV) tests. The Dynamic Shear Rheometer (DSR) Test, Hamburg Wheel Tracking, and Overlay Tester (OT) were used to evaluate the dynamic shear characteristics and performance of the modified RAP mixture. The test results show that using low-viscosity binder (LVB) positively affected the quality of reclaimed asphalt binder after prolonged aging periods. Additionally, the dynamic shear modulus of the AP1 mixture was 5% less than the reference mixture after the PAV condition, indicating a reduced stiffness effect. Considering the performance of reinforced RAP mixture, all RAP mixtures withstood a load of 20,000 cycles settling under 20 mm after 10,000 cycles. In mix COW1, COW5, and LVB, the final settlement was 3.75 mm, 3 mm, and 2.66 mm. Meanwhile, the load reductions of the above mixes were 73.3%, 74.2%, and 76.4% after 1000 OT cycles. In conclusion, utilizing LVB in RAP binder can produce equivalent benefits as applying a rejuvenator additive, even at a high asphalt content (40%) threshold. This research can offer insights into improving the performance of RAP binders in service and promoting the development of green construction.

Appraising the synergistic use of recycled asphalt pavement and recycled concrete aggregate for the production of sustainable asphalt concrete

Material obtained from the demolition of concrete structures and milling of flexible pavements has the highest potential for recyclability. This study aimed to evaluate the performance of hot mix asphalt with the concurrent use of recycled asphalt pavement (RAP) and recycled concrete aggregate (RCA). Contents of RAP and RCA were varied from 0% to 50% by fixing the total recycling materials percentage to 50%. Penetration grade 40/50 virgin binder and waste engine oil (WEO) as rejuvenator were used in the present study. A series of tests, such as Scanning electron microscopy (SEM), Marshall stability, indirect tensile strength test, IDEAL CT, uniaxial compression test, and resilient modulus test, were carried out to assess the performance of the prepared recycled asphalt mixtures. SEM images revealed the presence of the medium to fine particles on RCA indicating the rough surface texture. Except RAP10 (10% RAP plus 40% RCA) and RAP50 (50% RAP) mixes, all mixes had Marshall stability value greater than the control mix, the highest for RAP40 (40% RAP plus 10% RCA) mix followed by RAP0 (50% RCA) mix. In the case of resilient modulus, the effect of RAP is more pronounced till 40% resulting in an almost linear increase in values. Also, RAP40 exhibited the highest rutting and fatigue resistance. As far as moisture sensitivity is concerned, all the mixes performed satisfactorily as the tensile strength ratio (TSR) was greater than 80%. Overall, the major factors affecting the performance of recycled mixes were surface roughness, stiffness of the aged binder and rejuvenator.