Rutting Resistance Research Articles

Use of modified chitosan as bitumen modifier and its impact on rheological properties in bitumen modification.

Conventional bitumen is a viscoelastic material composed of asphaltene and maltene. It is prepared by air-blowing, but this approach makes the bitumen more brittle and susceptible to temperatures. To decrease the temperature susceptibility, synthetic polymers or additives are used to make polymer-modified bitumens. Polymer-modified bitumens have poor storage stability and phase separation and are costly. Chitosan has free amino and hydroxyl groups. Some studies showed that chitosan can be used as a bitumen emulsifier, increasing emulsion viscosity. This study describes the synthesis of O-carboxymethyl chitosan (OCMC) from chitosan, and the same was blended in base bitumen VG10 and VG30 to improve its constitutive properties. VG10 and VG30 grade bitumen were characterized for penetration, softening point, kinematic and absolute viscosity, and ductility. OCMC-modified bitumens were also characterized by their rheological and mechanical properties. OCMC was used in the concentration range of 0.5 to 4.5 wt%. The study revealed that using sulfur increases the ductility and penetration of modified bitumen with 1.5 wt% of OCMC and meets the specification of VG40-modified bitumen as per BIS specification IS:73:2013. The study showed that blending 1.5 wt% of OCMC in VG30 base bitumen enhances the complex modulus to 76,517Pa (at 42°C) with a minimum phase angle of 68.58° and meets the VG40 bitumen specification. Simultaneously, blending 1.5 wt% of OCMC in VG10 base bitumen enhances the complex modulus to 64,454Pa with a minimum phase angle of 77.39° (at 42°C) and meets the VG30 bitumen specification. Studies showed that using SBS in a small amount of 0.25 wt% along with modified chitosan improves the rutting resistance and shear modulus by more than 67°C at 1.1kPa.

Influence of Reed Fiber Length and Dosage on the Properties of Reed-Fiber-Modified Bitumen and Bituminous Mortar

In order to explore the feasibility and efficacy of reed-fiber-modified bitumen (RFMB), three lengths and three dosages of reed fibers were selected to modify bitumen and bituminous mortar, while the physicochemical properties of RFMB and RFMB mortar were analyzed. In this work, FTIR spectroscopy was employed to characterize the chemical impact of fiber on bitumen. The viscidity and rheology of RFMB and the tensile strength of RFMB mortar were evaluated using a Brookfield viscometer, dynamic shear rheometer, and monotonic tensile test. The results showed that adding fibers primarily affects the physical structure rather than the chemical composition of bitumen, confirmed by FTIR spectroscopy. RFMB viscosity increased with higher fiber dosage and fiber length. Rheological evaluations showed an enhanced complex shear modulus for RFMB, suggesting improved performance at higher temperatures but increased stiffness at lower temperatures, with the latter indicating reduced flexibility. RFMB also demonstrated superior fatigue and rutting resistance, albeit with compromised stress sensitivity. Tensile tests on RFMB mortar highlighted significant improvements, especially with longer fibers, while shorter 0.4 mm fibers showed modest reinforcement effects, possibly due to uneven distribution during sample preparation.

Investigating the efficacy of bio-rejuvenators in restoring aged asphalt binder properties

The asphalt binder used in pavements oxidizes quickly owing to the elevated temperatures, solar radiation, and exposure to atmospheric oxygen. In this study, epoxidized castor oil (ECO) and acrylated cashew nut shell liquid (ACNSL) were investigated as potential rejuvenators for use as aged binders. The binders were aged in the laboratory using short- and long-term aging methods. The additives and rejuvenated binders were characterized by Fourier transform infrared spectroscopy (FTIR). The properties of the rejuvenated binders were evaluated by frequency sweep, multiple stress creep and recovery (MSCR), and linear amplitude sweep (LAS) tests. The additives improved binder performance, particularly for the sample modified with 15 % cashew nut shell liquid (CNSL). The rheological parameters indicated that both the bio-rejuvenators increased the elasticity of the binder. Regarding the rutting resistance as measured by MSCR test, the results indicated that the sample with the 7 % ACNSL rejuvenated binder exhibited the best rutting resistance at both intermediate and elevated temperatures. Additionally, the fatigue resistance of the sample with 10 % ACNSL was higher than those of the other samples. This study indicates that the bio-oils used are potentially useful as rejuvenating agents for aged binders, thus enabling the recycling of aged asphalt binders.

Enhancing High-Temperature Performance of Flexible Pavement with Plastic-Modified Asphalt.

Previous studies indicate that traditional asphalt mixtures lack the ability to withstand the stresses caused by heavy traffic volumes under high temperatures. To enhance the rutting resistance of flexible pavement under high levels of temperature and loading, extensive laboratory experiments were carried out. A 60/70 grade bitumen was used as a neat sample for comparison. The study introduced three distinct polymers, polypropylene (PP), low-density polyethylene (LDPE), and acrylonitrile butadiene styrene (ABS), at varying concentrations by weight into the neat bitumen. Initially, conventional tests were performed to evaluate the conventional properties of both the neat and modified bitumen, while aggregate tests assessed the mechanical properties of the aggregates. Subsequently, a Marshall mix design was performed to determine the optimum bitumen content (OBC) in the asphalt mixture. Finally, wheel-tracking tests were performed under a specific load and temperature to investigate the rutting behavior of the modified asphalt mixtures. The results of this comprehensive study revealed that the modified asphalt mixtures displayed improved resistance to rutting compared to the neat asphalt mixture. Furthermore, it was also observed that the LDPE exhibited a superior performance against rutting, followed by the PP and ABS. At polymer contents of 3%, 5%, and 7%, the LDPE achieved reductions in rut depth of 13%, 24%, and 33%, respectively, outperforming both PP- and ABS-modified asphalt. These findings not only enhance our understanding of asphalt behavior under diverse conditions but also highlight the potential of plastic-modified asphalt as an effective solution for mitigating rutting problems in road pavements. By incorporating plastic modifiers into asphalt mixtures, this approach aligns with the principles of sustainable construction by reducing plastic waste while improving pavement durability and performance.

Enhancing fiber-reinforced asphalt binders via graphene oxide grafting: A novel interfacial modulation strategy

This study reports a novel interfacial enhancement strategy for fiber-reinforced asphalt binders. The graphene oxide (GO) nanosheets were used and grafted onto polyester (PET) and polyacrylonitrile (PAN) fibers in order to enhance the performance of modified asphalt binders. Prior to this, ultraviolet ozone (UVO) treatment was primarily adopted for activating the inert surface of fibers. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Scanning electron microscope (SEM) confirmed that GO-modified fibers were successfully prepared via surface modification. For the rheological properties determined by dynamic shear rheometer (DSR), the asphalt binders with GO-modified fibers exhibit improved high-temperature rutting resistance, better creep and recovery characteristics and increased anti-fatigue properties. Remarkably, it demonstrates that the recovery (R) value of GO-PAN modified asphalt binder is increased by 21.9 %, and the non-recoverable compliance (Jnr) value of GO-PET modified asphalt binder has been reduced by 31.9 % compared to that reinforced with the unmodified fiber in multiple stress creep recovery (MSCR) tests. These enhancements are mainly attributed to the increased roughness and modulus of the GO-grafted fibers, which promote effective stress transfer at the fiber-asphalt interfaces. Results from the atomic force microscope (AFM) indicate that the Young’s modulus of GO-PET and GO-PAN is 94.2 % and 260.0 % higher than that of PET and PAN, respectively. This research not only provides a simple and cost-effective method for improving the rheological performance, but also elucidates the enhancement mechanism of interfacial behavior in fiber-reinforced asphalt binders.

Enhancing Hamburg Wheel Tracking Test Analysis: A Novel Energy-Based Performance Index

Rutting and moisture damage are the most common distress types in the pavement; therefore, agencies have adopted performance tests such as the Hamburg wheel tracking test (HWTT) to specify and screen the asphalt concrete rutting performance, following the AASHTO T324 standard. Many studies have shown that the AASHTO parameters can be used to characterize and rank the performance of asphalt mixes. Additionally, researchers proposed new analysis methods and performance parameters to provide a more systematic approach to analyzing the HWTT results. However, some of these performance parameters are determined subjectively by the operator, which may result in ambiguous values, preventing agencies from adopting them in the specification. On top of that, it is also unclear whether each analysis method or the performance parameters can universally distinguish the rutting performance when applied to various HWTT results. Thus, this study investigates the feasibility of different HWTT analysis methods among the performance parameters. 61 HWTT results from various material combinations were analyzed using three different data analysis approaches and calculating the performance parameters. The result showed that the current analysis methods and parameters have certain limitations in analyzing HWTT results. Therefore, a performance parameter, namely the Hamburg performance index (HPI), was introduced, incorporating the number of passes, maximum rut depth, and rut path history into one parameter. It was found that the HPI can resolve the limitation encountered by other analysis approaches and significantly improve the accuracy of distinguishing a mix's rutting and moisture resistance.

Study on temperature regulation capability of asphalt mixture modified by dual phase change material used in ultra-thin overlay

ABSTRACT A dual-phase change material (DPCM) containing polyethylene glycol (PEG) 400/expanded graphite (EG) and PEG1500/EG with both high and low-temperature regulation capacities was prepared. It was added as an additive to the NovaChip-Type C asphalt mixtures. Laboratory and field temperature regulation tests were designed. The images taken by SEM showed that PEG was fully adsorbed by EG and the structure of DPCM was stable. The test results showed the DPCM has good durability in the cyclic phase change process. The modified asphalt binders with different DPCM content showed different heat storage capacity. The results of temperature regulation tests showed that the addition of DPCM effectively reduced the temperature change rate of asphalt mixtures. With 1.88% DPCM, the extremum of high temperature of asphalt mixtures reduced by 2.3°C while the extremum of low temperature increased by 2.0°C. In terms of road performance, the cracking resistance at low temperature of asphalt mixtures gradually improved with the increase of DPCM content. Meanwhile, the rutting resistance at high temperature and water damage resistance still met the requirements of the specification. The DPCM had a good effect on restraining the occurrence of road diseases caused by temperature and prolonging the service life of the road.

Influence of bio-based and refined rejuvenators on asphalt mixture with cold RAP

ABSTRACT In the recent years, research on the effects of rejuvenation on hot mix asphalt (HMA) with a high amount of RAP (Reclaimed Asphalt Pavement) has intensified. However, the vast majority of scientists focus on the technology of preheated RAP addition (e.g. in the parallel dryer). It was decided to investigate the effect of rejuvenators on asphalt mixtures containing non-preheated RAP (RAP cold addition into the mixer). Different types of rejuvenators were used in the research. The tests were carried out for the binder course and the base course. The optimal amount of cold RAP in the mixtures was determined and based on the initial tests of stiffness modulus and air void content, the amount of rejuvenators was adjusted for later tests. Tests of air void content, stiffness, resistance to water and frost and rutting resistance were carried out in the laboratory. Afterwards tests in the asphalt mixing plant were conducted for the rejuvenator with the best results for the base course. The results obtained confirmed the potential of using rejuvenators for mixtures with cold RAP addition into the mixer. It has been shown that bio-based rejuvenators are suitable for the use in different types of asphalt mixtures.

Degradation performance and mechanism of VOCs in asphalt by alkali metal-doped La2Ce2O7-based fluorite through pyroelectric and photocatalytic synergy

Under high-temperature construction conditions, the use of asphalt can release a large amount of volatile organic compounds (VOCs), which has adverse effect on the environment and human health. Part of fluorite oxides show potential application in VOCs conversion due to their excellent photoresponse and chemical stability in addition to ferroelectricity, piezoelectricity and pyroelectricity properties. In this paper, La2Ce2O7-based fluorite was modified with alkali metal doping and its photo-thermal coupling catalytic effects on the degradation performance of VOCs in asphalt were investigated. The results show that the fluorite catalysts La1.85A0.15Ce2O7 (A=Li, Na, K, Rb, Cs) have efficient electron-hole pair separation ability. Among them, the Rb+ doped La2Ce2O7 sample not only has stronger pyroelectric effect due to increased lattice distortion and oxygen vacancies, but also has the best photogenerated charge transport property and more favorable valence band position for oxidation reaction. Under the photo-thermal synergistic effect, the catalytic degradation performance of VOCs in asphalt by Rb+ doped La2Ce2O7 catalyst can reach 82.61 % at 50 min. Additionally, dynamic shear rheological tests indicate that the addition of catalysts at this blending ratio can enhance the rutting resistance of the asphalt material. This study introduces an innovative approach to enhance the efficiency of multi-field coupled degradation processes of volatile organic compounds (VOCs) in asphalt.

Property improvement of epoxy emulsified asphalt modified by waterborne polyurethane in consideration of environmental benefits

Waterborne epoxy modified emulsified asphalt (EMEA) has the shortcomings of insufficient toughness and poor aging resistance, which limits its application of low-carbon cold-paving technology in plateau zones. To obtain a cold-mix asphalt binder with excellent performance, waterborne polyurethane (WPU) was utilized to modify EMEA in this work. Properties, modification mechanism, action process, environmental benefits, and cost-benefit of composite-modified emulsified asphalt (CMEA) were analyzed. Results show that CMEA had good rutting resistance, low-temperature rheological, tensile toughness, adhesion with aggregate and moisture damage resistance, and aging resistance properties. These were closely related in that WPU was cross-linked with the waterborne epoxy resin (WER) to form an interpenetrating polymer network (IPN) structure, when the space network structure of WER and the soft and hard segments of WPU worked together. Based on the above results, it was recommended that EA containing 4.0 wt% WER was modified by 7.5 wt% WPU to achieve the best pavement properties. Furthermore, it was discovered that a physical process by which WER and WPU modified EA, served as a skeleton connection and toughening agent. CMEA has excellent performance and is especially suitable for use in low-temperature and strong aging areas, while can bring good environmental benefits.

Resurface of rubber modified asphalt mixture with stress absorbing membrane interlayer: From laboratory to field application

The increasing concern over tire pollution, exacerbated by the improper disposal of waste tires, serves as the backdrop for this research, which aims to explore the efficacy of incorporating ground tire rubber (GTR) into asphalt mixtures enhanced with a stress-absorbing membrane interlayer (SAMI). In this study, three variations of Hot Mix Asphalt (HMA) were evaluated: a conventional mix, a rubber-modified asphalt mixture (RMA), and a trans-polyoctenamer rubber (TOR) modified asphalt mixture in the laboratory. The assessment focused on the high and low-temperature performance of the asphalt mix and binder. Key findings from the laboratory tests indicate that the integration of a SAMI layer and GTR as additives markedly boosts the crack resistance of the asphalt mixture. Despite a reduction in fracture energy across all three HMA types following long-term aging, the GTR-modified HMA maintained superior fracture energy relative to the conventional mix. Initially, the inclusion of GTR adversely affected the mixture's rutting resistance. However, after undergoing long-term aging, both the conventional and GTR-modified HMAs exhibited exceptional rutting and moisture damage resistance. Field noise assessments further demonstrated that GTR-enhanced pavements produced noise levels approximately 2 dB lower than those of standard asphalt pavements. Additionally, pavements lacking a SAMI layer manifested low-severity cracking, with an average cracking frequency occurring every 2 ∼ 6 m, whereas pavements equipped with a SAMI layer exhibited no cracking following two winter seasons. The rubber asphalt overlay may increase the leaching of 6PPD-quinone, but the SAMI layer helps reduce tire wear particle generation by preventing road cracking. Rubber asphalt overlay leaching tests resulted in 6PPD-quinone concentrations lower than currently available toxicity data (LC50 for Coho Salmon, 0.095 ug/L). In conclusion, the utilization of dry-processed rubber asphalt mixes alongside a SAMI layer in pavement construction not only has the potential to extend the service life of pavements but also contributes to the production of quieter road surfaces. This study underscores the environmental and functional benefits of incorporating rubber modifications into asphalt pavements, presenting a viable strategy for mitigating tire pollution through the reuse of waste tires in infrastructure.

Experimental investigation on durability of prefabricated rollable asphalt: Creep and fatigue performance evaluation

Rollpave, a thin prefabricated rollable asphalt layer produced in a factory and rolled on a reel for laying on the existing surface, has attracted attention in the pavement industry due to its rapid treatment capabilities. However, the long-term durability of Rollpave needs further evaluation before considering widespread use. This study aims to assess the durability of Rollpave by evaluating the fatigue and creep performance of its modified bitumen and asphalt mixture. The results highlight that the creep stiffness of modified bitumen at −12°C is half of the corresponding value of virgin bitumen, and lowering the temperature to −18°C increases its creep stiffness to 78.44 MPa. At the same time, it is still 20 MPa less than virgin bitumen. Besides, it is showed the fatigue life of modified bitumen is 23 times greater than the corresponding value of virgin bitumen at 20°C and strain levels of 5 %, and modified bitumen has better stress relaxation ability leading to damage endurance. Additionally, it is observed that the flexural stiffness of the Rollpave mixture drops by only 23 % after 600,000 cycles under 400 µɛ repeated loading. Furthermore, it is indicated that although the creep performance of Rollpave is sensitive to stress and temperature, it has a noticeable recovery ability and rutting resistance, with the average value of non-recoverable creep compliance and percent recovery at stress level of 3.2 kPa at 64°C being 0.213 kPa−1 and 54 %. The asphalt dynamic creep test results of the Rollpave mixture also indicated nearly 20,000 µɛ of cumulative permanent strain at 50°C in the 9000th loading cycle.

Enhancing Asphalt Binder Performance and Storage Stability with Trinidad Lake Asphalt (TLA)

This study delves into the transformative effects of Trinidad Lake Asphalt (TLA) on asphalt binders, revealing significant improvements in various performance metrics. Our findings indicate that TLA substantially increases binder viscosity and enhances rutting resistance, as evidenced by elevated G*/sin δ values in both original and RTFO-aged states. TLA-modified binders demonstrate superior rheological properties, including improved Jnr and percentage recovery, indicating enhanced resistance to permanent deformation and reduced fatigue cracking. However, an increase in TLA content correlates with higher G*·sin δ values, suggesting a trade-off with fatigue resistance and a higher susceptibility to cracking. Additionally, while TLA initially improves binder flexibility at low temperatures, excessive content can increase stiffness, adversely affecting stress relaxation properties. Notably, TLA enhances storage stability, ensuring minimal phase separation and excellent homogeneity. These insights underscore the need for the precise control of TLA content to optimize pavement durability. Future research should focus on fine-tuning TLA incorporation with additives like crumb rubber to maximize the structural integrity and longevity of asphalt pavements.

Influence of preparation parameters on rheological properties and relation analysis of waste rubber modified bitumen mastic

Waste rubber modified bitumen has gained significant attention as a sustainable and innovative material in the field of pavement engineering. This study aims to evaluate the performance of rubber modified bitumen mastic by considering its rheological properties, specifically focusing on preparation parameters, i.e., rubber content, mesh number, and filler to bitumen ratio. From the experimental results, the rheological properties of rubber modified bitumen mastic were significantly influenced by preparation parameters. Increasing the rubber powder content in bitumen mastic results in higher viscosity. Increasing the rubber content improves high-temperature rutting resistance to a certain extent, however, excessive rubber powder content would result in weakened high-temperature performance improvement. The rutting factor decreases gradually with an increase in the rubber mesh number. A ratio of filler to bitumen of 0.95 exhibits the best resistance to rutting at high temperatures. Higher rubber content and larger mesh number correspond to stronger low-temperature crack resistance in bitumen mastic. As the ratio of filler to bitumen increases, the low-temperature deformation capacity gradually decreases, resulting in weaker low-temperature crack resistance. Based on the grey relation analysis, the ratio of filler to bitumen has the greatest impact on the high and low-temperature rheological properties of bitumen mastic, followed by the rubber content. The rubber mesh number has a relatively lower impact. It is crucial to control the ratio of filler to bitumen to avoid excessive values. When possible, a higher rubber powder content should be used while meeting process requirements. These findings provide valuable insights into the design and optimization of rubber modified bitumen mastic, which can contribute to the development of sustainable and high-performance bitumen mixtures, promoting the use of recycled rubber in pavement engineering.

The Rejuvenation Effect of Bio-Oils on Long-Term Aged Asphalt.

Generally, rejuvenators are used to supply missing components of aged asphalt, reverse the aging process, and are widely used in asphalt maintenance and recycling. However, compared with traditional rejuvenators, bio-oil rejuvenators are environmentally friendly, economical and efficient. This study looks into the effect of the three different bio-oils, namely sunflower oil, soybean oil, and palm oil, on the physical properties, rheological properties and chemical components of aged asphalt at different dosages. The asphalt physical properties and Dynamic Shear Rheological (DSR) test results show that with the increase in bio-oil, the physical properties and rheological properties of rejuvenated asphalt are close to those of virgin asphalt, but the high-temperature rutting resistance needs to be further improved. The results of Fourier Transform Infrared Spectroscopy (FTIR) show that the carbonyl and sulfoxide indices of rejuvenated asphalt are much lower than those of aged asphalt. Moreover, the rejuvenation efficiency of aged asphalt mixed with sunflower oil is better than that with soybean oil and palm oil at the same dosage.

Assessing the impact of discarded plastic bottles on the resistance to rutting in hot mix asphalt

Undoubtedly, the damage to the upper layer of road pavement caused by the tremendous load of vehicles and climate factors is alarming and challenging to both the government and researchers in the respective field. Addressing these challenges requires innovative solutions to enhance pavement durability and sustainability. In this context, the authors seek to assess the impact of incorporating waste polyethylene terephthalate (PET) as a modifier on asphalt mixture properties. This study investigates the potential of PET, a commonly discarded plastic, to improve the performance of asphalt pavements. The authors conducted evaluations on the rutting performance of asphalt blends containing different PET percentages (0%, 0.2%, 0.6%, 0.8%, 1%) and diverse PET sizes (12 × 3 mm, 20 × 3 mm, and 30 × 4 mm). The experimental approach included dynamic creep tests and the use of a Hamburg wheel tracking device to simulate real-world traffic conditions and measure the mixtures' resistance to deformation. The findings revealed that incorporating PET into asphalt mixtures significantly enhances rutting resistance. Specifically, the addition of PET content improved the viscoelastic properties of the asphalt, making it more resistant to permanent deformation under load. However, the size of PET particles was found to play a crucial role in performance. Larger PET sizes were associated with a decrease in rutting resistance, suggesting an optimal particle size must be determined to maximize benefits. These results support the idea that the careful selection of PET content and size can significantly improve the performance and longevity of asphalt pavements. This approach not only addresses the issue of plastic waste but also contributes to the development of more sustainable infrastructure. By incorporating PET, the research highlights a viable method for enhancing road durability and supporting environmental sustainability, offering a promising solution for future road construction projects.

Preparation and thermal performance testing of diatomite-modified asphalt pavements

In this study, the efficacy of diatomite as a modifier in asphalt pavements is thoroughly examined. The research primarily focuses on evaluating the thermal performance of asphalt mixtures modified with varying diatomite contents. Key findings indicate significant improvements in the rutting resistance, with the dynamic stability of the 15% diatomite mixture being 3.4 times higher than the control mixture. Additionally, the 10% diatomite mixture shows a 20% increase in bending strain energy density, enhancing low-temperature performance. However, a diatomite content beyond 10% tends to diminish these benefits. Fatigue life at 10% diatomite content is improved by 18%–24%, demonstrating the material’s potential in extending pavement longevity. Water stability tests also reveal notable improvements, with the 15% diatomite mixture exhibiting a 15% increase in tensile strength ratio post-water conditioning. These results collectively establish diatomite as a cost-effective and efficient modifier for asphalt pavements, promoting enhanced durability and performance.

Performance Evaluation and Modification Mechanism Analysis of High-Viscosity Modified Asphalt

Abstract High-viscosity modified asphalt (HVMA) has important application potential in pavement engineering, such as porous asphalt pavements and ultrathin overlays. To comprehensively study and evaluate the overall performance of HVMA, five HVMA samples were prepared using modifier with dosages of 6 %, 9 %, 12 %, 15 %, and 18 %, respectively. The basic physical properties of HVMA were evaluated according to standard physical asphalt performance tests. The overall rheological properties of HVMA were assessed using temperature sweep tests, frequency sweep tests, and multiple stress creep recovery tests. Fluorescence microscopy was employed to analyze the microscopic characteristics and the modification mechanism of HVMA. The results show that the high-viscosity modifier could improve the overall rheological properties of HVMA at both high and low temperatures, with approximately 9 % determined as the optimal dosage. HVMA had better performance than matrix asphalt in high-temperature rutting resistance, permanent deformation resistance, temperature sensitivity, and elastic characteristics. At an appropriate dosage of the high-viscosity modifier, the modifier absorbed the light components in the asphalt, causing them to swell and dissolve. As a result, the modifier could be uniformly dispersed in the asphalt, thereby significantly improving the high-temperature stability of HVMA. The results of this paper may be helpful to the mechanism research and application of HVMA.

Laboratory performance and field demonstration of asphalt overlay with recycled rubber and tire fabric fiber

The escalating number of vehicles has precipitated a surge in tire production, resulting in an increased accumulation of waste materials such as ground tire rubber (GTR) and tire fabric fibers. Integrating recycled materials into asphalt pavement stands as a viable solution to mitigate the issue of waste accumulation. The objective of this study was to assess the durability and aging resistance of hot mix asphalt (HMA) enhanced with GTR and tire fabric fibers, in contrast to traditional HMA. A high-quality pavement incorporating GTR, and tire fibers was constructed in Michigan. Findings indicated that the inclusion of tire fabric fibers markedly bolstered the rutting and cracking resistance of HMA. Viscoelastic testing further confirmed the superior rutting and cracking resistance of the asphalts modified with GTR alone and in combination with tire fibers, relative to conventional asphalt. Additionally, field evaluations of noise levels showed a 2–3 dB decrease in noise with GTR-modified asphalt pavements, and after two years in service, the overlays modified with GTR and fibers exhibited no cracking. Ultimately, asphalt pavements modified with both rubber and tire fibers demonstrated enhanced performance over traditional pavements, offering a quieter and more durable roadway solution.

Investigating the influence of stress dependency on the evaluation of high-temperature deformation resistance in SBS-modified asphalt

The rheological responses of Styrene-Butadiene-Styrene (SBS) modified asphalt are stress-dependent, yet the underlying mechanisms and their relationship to the phase structures formed by SBS in the asphalt matrix remain unclear. To address this issue, this study utilized varying dosages of SBS to prepare binders (SBSMA), which were then characterized through fluorescence microscopy, FTIR, and rheological tests including temperature sweeps and Multi-Stress Creep Recovery (MSCR) at four stress levels. Additionally, rutting resistance of the mixtures was evaluated using wheel tracking tests, correlating the results with rheological data. The test results indicate that the formation of a three-dimensional SBS network structure within the asphalt significantly increases the Stress Sensitivity Index (SSI) by 69.5 %, thereby enhancing the binder's stress sensitivity. Based on the theory of entropic elasticity, the stress sensitivity of SBSMA is explained. The cross-linked network structure exhibits superelastic behavior under low stress but may be overstretched and reorganized under high stress, leading to weakened entropic elasticity. Furthermore, the Jnr values obtained at higher stress levels show stronger correlation (r > 0.9) with the Dynamic Stability (DS) from the wheel tracking test results. This finding suggests that entropic elasticity does not significantly improve the rutting resistance performance at the mixture level. Consequently, increasing the stress level in MSCR tests is recommended to more accurately predict the binder’s rutting performance by inhibiting the network's entropic elasticity.