Wheel Tracking Test Research Articles

Long-term rutting prediction of gussasphalt steel bridge deck pavement based on comprehensive finite element modelling

ABSTRACT Gussasphalt is widely used for steel bridge deck pavements, but it is prone to rutting during the operational stage. This paper proposes a finite element-based method for predicting rutting in gussasphalt steel bridge deck pavements. Based on the Nanjing Yangtze River Fourth Bridge project, asphalt mixture specimens were prepared and tested in the laboratory. The viscoelastic-plastic constitutive model was fitted via dynamic modulus test and uniaxial repeated loading creep test results. Wheel track tests were conducted to validate the numerical model. The temperature gradient was obtained using actual environmental data and validated using actual data from buried thermocouples. Based on the equivalent conversion and simplification of traffic loads, the permanent deformation of the pavement layer was calculated using both the viscoelastic-plastic constitutive model and the time-hardening creep constitutive model. The viscoelastic-plastic constitutive model yields an average relative error of 25% and an absolute error of 0.57 mm, while the time-hardening creep constitutive model shows an average relative error of 40% and an absolute error of 1 mm. The results indicate that the viscoelastic-plastic constitutive model can more accurately predict the long-term rutting of the steel bridge deck pavement.

Sustainable application of recycled plastics in asphalt pavement: Case study of a trial in Newtonville, Ontario, Canada

Global research on using plastic waste in asphalt roads highlights its benefits: recycling waste, reducing greenhouse gas emissions, and providing an alternative to non-renewable asphalt binders. This study aims to bridge the gap between laboratory results and field performance of recycled plastic-modified asphalt in cold regions, promoting broader adoption. Laboratory analysis of core samples was performed as part of a quality assurance program. High-temperature rutting resistance was evaluated using the Hamburg wheel tracking test, while low-temperature cracking resistance was assessed through semi-circular bending testing. Results show that the impact of recycled plastics and fibers on rutting resistance varies with temperature, with the greatest benefit at the highest temperatures. For low-temperature cracking resistance, polyethylene terephthalate (PET) fibers outperform mixed plastics by delaying crack propagation. Low-temperature conditioning can induce thermal shrinkage in the asphalt mixture, slightly moderating the effects of recycled plastics and fibers.

Influence of Basalt Fiber Morphology on the Properties of Asphalt Binders and Mixtures.

Basalt fiber (BF) has been proven to be an effective additive for improving the properties of asphalt mixtures. However, the influence of basalt fiber morphology on the properties of asphalt binders and mixtures remains inadequately explored. In this study, chopped basalt fiber (CBF) and flocculent basalt fiber (FBF) were selected to make samples for testing the influence of the two types of basalt fibers on asphalt materials. Fluorescence microscopy was used to obtain the dispersion of fiber in asphalt binders. Then, a temperature sweep test and a multiple stress creep recovery (MSCR) test were carried out to appraise the rheological characteristics of the binder. Moreover, the performance of the fiber-reinforced asphalt mixture was evaluated by a wheel tracking test, a uniaxial penetration test, an indirect tensile asphalt cracking test (IDEAL-CT), a low-temperature bending test, a water-immersion stability test, and a freeze-thaw splitting test. The results indicate that the rheological behavior of asphalt binders could be enhanced by both types of fibers. Notably, FBFs exhibit a larger contact area with asphalt mortar compared to CBFs, resulting in improved resistance to deformation under identical shear conditions. Meanwhile, the performance of the asphalt mixture underwent different levels of enhancement with the incorporation of two morphologies of basalt fiber. Specifically, as for the road property indices with FBFs, the enhancement extent of DS in the wheel tracking test, that of RT in the uniaxial penetration test, that of the CTindex in the IDEAL-CT test, and that of εB in the low-temperature trabecular bending test was 3.1%, 6.8%, 15.1%, and 6.5%, respectively, when compared to the CBF-reinforced mixtures. Compared with CBFs, FBFs significantly enhanced the elasticity and deformation recovery ability of asphalt mixtures, demonstrating greater resistance to high-temperature deformation and a more pronounced effect in delaying the onset of middle- and low-temperature cracking. Additionally, the volume of the air void for asphalt mixtures containing FBFs was lower than that containing CBFs, thereby reducing the likelihood of water damage due to excessive voids. Consequently, the moisture susceptibility enhancement of CBFs to asphalt mixture was not obvious, while FBFs could improve moisture susceptibility by more than 20%. Overall, the impact of basalt fibers with different morphologies on the properties of asphalt pavement materials varies significantly, and the research results may provide reference values for the choice of engineering fibers.

Towards the high RAP dosage obtained by refined processing influence on comprehensive performance of recycled asphalt mixture

The severe agglomeration of Reclaimed Asphalt Pavement (RAP) particles not only leads to high gradation variability during recycling, but also impedes the miscibility between new-old binders. This phenomenon imposes significant limitations on maximizing the utilization of RAP with high content and value. This paper first realized the effective separation of asphalt milling material by the self-developed RAP refined processing equipment to obtain coarse RAP with low binder content and fine RAP with high binder content. The fine RAP with high binder content underwent a deep rejuvenation process, and the recovery efficiency of the asphalt mortar was evaluated by CT scanning test, microscope observation test, and dynamic shear rheology test. Moreover, to investigate the strength formation characteristics of recycled asphalt mixtures with high RAP content, specific tests including wheel tracking test, three-point bending test, Hamburg Wheel Tracking test, dynamic modulus test, and two-point bending fatigue test, were conducted. By using the refined processing equipment, the asphalt film on the RAP can be precisely removed, thereby addressing the issue of aged binder agglomeration. In the coarse RAP with low binder content, the binder content was reduced to 1.48 %, allowing it to be used as a direct substitute for new aggregate, whereas the binder content of fine RAP exceeded 10 %. It was found that the direct incorporation of unrefined RAP enhanced the high-temperature stability and dynamic modulus of recycled asphalt mixture, but impacted their low-temperature cracking resistance, moisture stability, and fatigue performance. After refined processing and differentiated recycling design, the agglomeration of aged binder was reduced and the miscibility of new-old binders was improved, effectively enhancing the comprehensive performance of the recycled asphalt mixture. It should be noted that the mixing homogeneity and miscibility decrease as the RAP content exceeds 75 %, resulting in the reduction of moisture stability, cracking resistance, and fatigue performance of recycled asphalt mixture.

Performance evaluation of the recycled asphalt mixture based on cold patch asphalt for pavement repair

ABSTRACT Compared with a hot recycle of asphalt pavement, a cold recycle is more friendly to the environment. Moreover, it is more economical and convenient if a cold recycled asphalt mixture is stored for pothole repair. This study aims to combine cold patch technology and recycling technology to produce a recycled cold patch asphalt mixture (CPAM) and evaluate its performance. To achieve this objective, the diffusion between aged asphalt and cold patch asphalt (CPA) is evaluated to prove the promotion of stored time for the recovery of aged asphalt. Then recycled CPAM is designed according to cold patch technology combined with treatment technology of the recycled asphalt mixture. Finally, comprehensive laboratory tests, including wheel tracking tests, trabecular bending tests, immersing Marshall stability tests, Hamburg wheel-tracking tests and rubbing tests, are conducted to evaluate and compare the performances of recycled CPAM. It is found that the proposed cold patch recycle method provided significantly better high-temperature performance, low-temperature performance, moisture susceptibility and working ability of recycled CPAM. In addition, the stored time of recycled CPAM significantly influences the diffusion of CPA and recycled asphalt, which is directly related to the recovery of aged asphalt and the performance of recycled CPAM.

Exploring the effects of waste plastic aggregate on styrene-butadiene-styrene-modified asphalt binders for sustainable rural pavements

In addressing the imperative need for sustainable and cost-effective solutions in rural pavement development, this study navigates the intricate balance of environmental and financial constraints to ensure the resilience of infrastructure in communities with limited resources. The focal point is the integration of waste plastic aggregate (WPA) into hot mix asphalt, augmented by the inclusion of styrene-butadiene-styrene (SBS) for an elevated level of performance. The findings underscore a gradual decrease in the tensile strength ratio, emphasizing a manageable impact, transitioning from 82.4% in the control to 73.7% at 6% WPA. Noteworthy is the observation of marginal reductions in indirect tensile strength and stiffness, particularly notable at higher WPA levels. Dynamic modulus testing highlights susceptibility to rutting at lower frequencies, while high-frequency results demonstrate stability up to 6% WPA. The Hamburg wheel tracking test signals heightened rutting at 3% and 6% WPA, indicating potential challenges in deformation resistance. Despite a slight dip in strength, the discernible magnitude of this reduction is not substantial. This affirms that the incorporation of WPA achieves a harmonious enhancement of sustainability without compromising critical mechanical properties.

Effect of Recycled Asphalt Mixture and Solid Waste-Based Solidification Materials on Performance of Cold-Regenerated Asphalt Mixture

In this study, an aging asphalt mixture was regenerated by a waste-based rejuvenator and cemented by solid waste-based solidification materials (SSMs). A splitting test, wheel tracking test, and three-point bending test were conducted to evaluate the properties of the regenerated asphalt mixture (RAM). The results reveal that the properties of the asphalt mixture were not diminished or were moderately enhanced by the 30% substitution of RAP. With the substitution of RAP to 100%, the splitting tensile strength, dynamic stability, and splitting strength ratio were decreased by 13%, 15%, and 5%, respectively. With the 100% substitution of SSMs for cement, the compressive strength, dynamic stability, flexural strain, and splitting strength ratios of the RAM were increased by 40%, 32%%, 14%, and 8%, respectively. The lightweight components can be supplemented, and low-temperature deformation and interlayer flowability can be improved by the incorporation of the rejuvenator. The generation of hydrated calcium silicate and ettringite for SSMs is greater than those of cement. The massive generation of ettringite has been observed to increase the solid phase volume by 120%, which may facilitate a more complete filling of the remaining pores in the RAM due to water evaporation. The regeneration and cement on green and the high performance of the rejuvenator and the SSM markedly enhanced RAM performance.

Impact of Nanocarbon-Coated Calcium Carbonate on Asphalt Rutting: Experimental and Numerical Analyses

Rutting is a significant form of pavement distress that arises from irreversible strains accumulating along wheel paths, directly impacting pavement safety. This research investigates the effectiveness of nanocarbon-coated micronized calcium carbonate powder as a modified filler to mitigate rutting, utilizing numerical methods via finite element software. The study specifically examines the addition of 5% by weight of this modified filler to the asphalt mix. To validate the numerical results, laboratory wheel-tracking tests were conducted on samples incorporating both conventional and modified fillers. The findings reveal that the modified calcium carbonate filler enhances the asphalt’s resistance to rutting, with the 5% inclusion demonstrating a marked improvement in durability and performance. The study also underscores the necessity of characterizing the elastic and visco-plastic properties of materials through rigorous testing methods, such as elastic modulus and dynamic creep tests, to better understand their behavior under load. Numerical analysis based on linear elastic conditions was prioritized over viscous conditions to effectively compare the results of these specialized materials. The strong correlation between the numerical simulations and laboratory results reinforces the effectiveness of finite element methods in predicting pavement behavior and optimizing asphalt mixtures.

Rheological and mechanical evaluation of a novel fast curing cold asphalt concrete made with asphalt emulsion, by-products and magnetic induction

This work studies the feasibility of a new cold asphalt concrete with 5 % voids with fast curing, developed with asphalt emulsion and magnetic induction. Until now, it was impossible to produce fast curing cold asphalt concretes due to the impossibility of compacting and evaporating the water in the asphalt emulsion quickly. Therefore, the aim of this work is to solve the impossibility of compacting the cold asphalt concrete and thus reduce the long curing times. For this purpose, at laboratory level, an experimental cold asphalt concrete was designed with magnetic induction and compared with two reference hot asphalt concretes manufactured according to Spanish standards without magnetic induction (one with 50–70 grade bitumen and another with a PMB45/80–65 type polymer-modified bitumen). The research was carried out in two stages. First, the new cold asphalt concrete was rheologically characterized, the binder recovered from the asphalt concrete was analyzed according to the tests of ring and ball, penetration, dynamic shear rheometer (DSR) and multiple stress creep and recovery (MSCR). Secondly, the new cold concrete asphalt was mechanically characterized, the mechanical performance of the cold asphalt concrete was analyzed by evaluating stability and deformation, dry and wet indirect tensile strengths (ITS), wheel tracking test, stiffness modulus and resistance to raveling dry and wet conditions. Based on the rheological analysis results, the asphalt emulsion recovered from the cold asphalt concrete is extremely soft with a low softening point and a high penetration rate. On the other hand, the values of viscosity, phase angle, stiffness and non-recoverable creep compliance are between those of the bitumen 50/70 and the PMB45/80–65, but closer to bitumen 50/70. As for their mechanical performance, the novel cold asphalt concrete studied presents better resistance to water damage and particle loss, both in dry and wet conditions, but also high permanent deformations and low ITS, probably due to the fact that the residual binder of the emulsion used is softer than the others.

Performance of plant-produced asphalt mixtures for balanced mix design implementation

ABSTRACT Several transportation agencies in Canada are currently relying on volumetric properties of asphalt mixtures to accept or reject the final mix design. The existence of various pavement defects on Canadian roads indicates that volumetric mix design procedure alone does not guarantee adequate long-term pavement performance. Therefore, transportation agencies are finding ways to increase durability of their asphalt mixtures to accomplish a road network that is more sustainable, safer and more economical. The balanced mix design (BMD) approach integrates two or more performance test criteria into mix design and acceptance to produce asphalt mixtures that are resistant to cracking and permanent deformation. The main objective of this study is to assess cracking and rutting performance of plant-produced asphalt mixtures to validate current volumetric mix design methods and investigate ways to optimise mix performance for moving towards an efficient BMD framework. Six plant-produced mixtures were collected from different pavement construction projects to prepare specimens for cracking and rutting evaluation. Cracking performance was determined using the Illinois flexibility index test and rutting performance was determined using the Hamburg wheel-tracking test. Results showed that polymer-modified binders, recycled materials and reduction of nominal maximum aggregate size contributed to better rutting performance. Nevertheless, limestone aggregates, recycled asphalt shingles and low asphalt content reduced cracking resistance and did not lead to an efficient BMD framework.

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.

The Production of Porous Asphalt Mixtures with Damping Noise Reduction and Self-Healing Properties through the Addition of Rubber Granules and Steel Wool Fibers.

Conventional asphalt roads are noisy. Currently, there are two main types of mainstream noise-reducing pavements: pore acoustic absorption and damping noise reduction. However, a single noise reduction method has limited noise reduction capability, and porous noise-reducing pavements have a shorter service life. Therefore, this paper aimed to improve the noise-damping performance of porous asphalt mixture by adding rubber granules and extending its service life using electromagnetic induction heating self-healing technology. Porosity and permeability coefficient test, Cantabro test, immersion Marshall stability test, freeze-thaw splitting test, a low-temperature three-point bending experiment, and Hamburg wheel-tracking test were conducted to investigate the pavement performance and water permeability coefficients of the mixtures. A tire drop test and the standing-wave tube method were conducted to explore their noise reduction performance. Induction heating installation was carried out to study the heating rate and healing performance. The results indicated that the road performance of the porous asphalt mixture tends to reduce with an increasing dosage of rubber granules. The road performance is not up to the required standard when the dosage of rubber granules reaches 3%. The mixture's performance of damping and noise tends to increase with the increase of rubber granule dosage. Asphalt mixtures with different rubber granule dosages have different noise absorption properties, and the mixture with 2% rubber granules has the best overall performance (a vibration attenuation coefficient of 7.752 and an average absorption factor of 0.457). The optimum healing temperature of the porous asphalt mixture containing rubber granules and steel wool fibers is 120 °C and the healing rate is 74.8% at a 2% rubber granule dosage. This paper provides valuable insights for improving the noise reduction performance and service life of porous asphalt pavements while meeting road performance standards.

High-quality utilization of reclaimed asphalt pavement (RAP) in asphalt mixture with the enhancement of steel slag and epoxy asphalt

Achieving high-quality utilization of reclaimed asphalt pavement (RAP) is challenging due to the subpar technical performance of aggregates and the aging of asphalt within RAP. This study investigates the use of epoxy asphalt (EA) and steel slag to enhance recycled asphalt mixtures (RAM) for superior performance and increased RAP content. The rheological performance of epoxy asphalt (EA) was evaluated using a dynamic shear rheometer (DSR), and its curing process was analyzed. Steel slag-epoxy recycled asphalt mixtures (SRAM) with 40 %, 80 %, and 100 % RAP were prepared, and their road performance was assessed through Marshall, wheel tracking, and semi-circular bending tests. Additionally, the effects of steel slag’s surface morphology and element distribution on moisture and skid resistance were examined. The volatile organic compound (VOC) emission characteristics were also studied. The results show that EA forms a uniformly dispersed structure, providing excellent high-temperature deformation resistance. EA and steel slag significantly enhanced the road performance of SRAM, with SRAM-80 (80 % RAP, 20 % steel slag) achieving a dynamic stability of 15027 times/mm. Steel slag improved SRAM-80’s skid resistance, with a British pendulum number (BPN) of 68 and a texture depth (TD) of 0.5889 mm. Compared to 60/80 asphalt, EA reduced VOC emissions by over 75 %. Incorporating 80 % RAP and 20 % steel slag into RAM effectively utilizes RAP while enhancing performance.

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.

Visco-plastic deformation characteristics of accelerated-aging asphalt mixture containing reclaimed asphalt pavement regenerated with crumb rubber based on Hamburg Wheel-Track test

The regeneration of the reclaimed asphalt pavement (RAP) with incorporation of crumb rubber was a cleaner alternative for reducing the fossil and ore resources consumption. For the desert area like Egypt, the rut of reclaimed pavement was principal contradiction during a long service. This work mainly characterized the visco-plastic deformation of accelerated-aging rubberized reclaimed asphalt mixture based on Hamburg Wheel-Track test. Four mixtures were designed by two contents of RAP (15% and 30%), two contents of crumb rubber (5% and 15%), and two asphalts (pen-#70 and pen-#90). Specifically, this work focused on the determination of accelerated aging effect, and analysis of rutting deformation fitting including overall deformation and visco-plastic deformation. Then, effect of accelerated aging time and material compositions on visco-plastic deformation was analyzed. In addition, the correlation analysis among indicators evaluating rutting deformation of mixture was conducted, and the correlation analysis between rutting deformation of mixture and average recovery rate at 3.2 kPa of extracted bitumen was completed. The results demonstrated that the accelerated aging equivalent factor of sunlight was approximately 6, meaning that one day of accelerated aging was equivalent to six days of natural aging in Cairo. With the accelerated aging time increased, resistance to rutting deformation of rubberized reclaimed asphalt mixture was promoted with the incorporation of RAP, crumb rubber and soft matrix binder. Meanwhile, dynamic stability, derived from fitting curve of visco-plastic deformation, was positively correlated with accelerated aging time, and it could accurately evaluate visco-plastic deformation characteristics of reclaimed mixture. Finally, visco-plastic deformation characteristics of reclaimed mixture was closely related to the permanent deformation resistance of binder at high temperature.

Recyclability potential of waste plastic-modified asphalt concrete with consideration to its environmental impact

The use of waste plastic into asphalt concrete paving mix (ACP) has been explored in recent literature to improve the functional properties of the mix. However, exploration on their recyclability potential at the end of its service life remains scarce. This study explores the potential of recycling aged waste plastic-modified asphalt concrete (AACP) for road pavements, with focus on four commonly disposed household plastics: high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS) and polyethylene (PET). Marshall stability test, Cantabro abrasion test, indirect tensile strength test, resilient modulus (MR) test, Hamburg’s wheel tracking test and stripping test were performed to evaluate the engineering properties of recycled waste plastic-modified asphalt concrete (RACP) containing proportions ranging from 20 % to 100 % aged component (AACP) blended with virgin mixtures. This paper highlights significant engineering performance of RACP, and most notably for RACP containing PP with 20 % aged content which exhibits 1.6 times greater resistance to moisture damage compared to conventional recycled asphalt concrete (RAPA). Although RACP with HDPE and PP (consisting of 20 % and 40 % AACP in mix) yield improvements in resilient modulus over RAPA, this improvement is less pronounced for RACP with PS and PET. Overall, RACP with 40 % aged components exhibits better rutting, moisture damage and abrasion loss performance, along with improved stability and flow value. Environmental impact in terms of water leachability was also found to be negligible in this study and RACP can be considered a feasible sustainable pavement material, with potential for second and more lives.

Influence of Carbon Fibers on the Rutting Susceptibility of Sustainable HMA Mixtures with Untreated Recycled Concrete Aggregates

This paper focuses on achieving sustainability to reduce the detrimental effect on the environment and the economic aspects by including several ratios of coarse recycled concrete aggregates (RCA) (25, 50, 75, and 100%) in asphalt mixtures. The methodology included testing all raw materials, the wheel tracking test to assess mechanical performance, and the Marshall design approach to determine the appropriate asphalt content. The outcomes demonstrated no discernible difference between the volumetric characteristics of the asphalt mixtures containing RCA and the control mix. Marshall's stability rose by 14.2% when 50% of the mixture contained RCA compared to the control combination. All combinations containing RCA were performed inferiorly to the control mixture regarding rutting. 19.63% was the greatest increase in rut depth for combinations made entirely of recycled concrete aggregate. Several percentages of 0.2, 0.25, and 0.3% carbon fibers were added to the total weight of the asphalt mixture to enhance rutting performance. Marshall's stability and resistance to rutting have significantly increased, attributable to the carbon fibers; nonetheless, the volumetric properties of the asphalt mixture have only slightly altered. The combinations with 0.3% carbon fiber reinforcement and 50% RCA showed the largest gain in Marshall stability, up 34.6% above the control mixture. The same combination had the strongest resistance to rutting, which was —39.08% higher than the control mixture.

Damage characterization of high- and low-temperature performance of porous asphalt mixtures under multi-field coupling

Porous asphalt (PA) have attracted considerable interest due to their functional advantages such as significant water permeability and noise attenuation properties. Nevertheless, its vulnerability to damage significantly hinders its widespread application. Therefore, this paper aims to investigate the damage characteristics of PA's high- and low-temperature performance under the coupled effects of moisture and temperature. Firstly, Hamburg Wheel-Tracking Test (HWTT) and three-point bending tests were conducted on PA under different coupling conditions. Subsequently, its damage characteristics were analyzed using the three-stage permanent deformation model, logistic model, and two-way analysis of variance (ANOVA) method. The findings indicate that under dry conditions, PA-13 exhibits a linear decrease in rutting resistance within the temperature range of 40–60 °C, followed by a significant decrease at 70 °C. During immersion in water, PA-13 undergoes a second and third-stage rutting evolution process, with an accelerated creep rate observed at 70°C. High temperatures exacerbate the viscoelastic damage of PA-13, while multi-field coupling promotes the simultaneous occurrence of viscoelastic damage and stripping damage. Furthemore, the results of the two-way ANOVA indicate that moisture has a more significant impact on high-temperature performance damage. In addition, in a dry environment, the low-temperature crack resistance of PA-13 deteriorates with decreasing temperature, but there is little difference at −20 °C and −30 °C. This is attributed to PA-13 exhibiting flexible cracking at 0 °C and −10 °C, while undergoing brittle cracking at −20 °C and −30 °C. Additionally, the coupled effect of temperature and moisture reduces the damage tolerance of PA-13 and accelerates its cracking process. The results of the two-way ANOVA indicate that both low temperature and treatment methods have a statistically significant impact on low-temperature performance, with treatment methods having a higher degree of influence. The findings of this paper contribute to an in-depth understanding of the damage mechanism of PA-13.

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.

Advancing Sustainability and Performance with Crushed Bottom Ash as Filler in Polymer-Modified Asphalt Concrete Mixtures.

Amid the growing demand for sustainable pavement solutions and the need to incorporate recycled materials into construction practices, this study explored the viability of using crushed thermal power plant bottom ash as a filler in polymer-modified asphalt concrete mixtures. Conventional lime filler was replaced with bottom ash at varying levels (0%, 25%, 50%, and 75%), and the resulting mixtures were evaluated using several performance tests. The optimal replacement level was determined to be 25%, based on the results of the indirect tensile strength (ITS) test. Comparisons between the control mixture and the 25% bottom ash-modified mixture were conducted using the dynamic modulus test, Cantabro test, Hamburg wheel tracking (HWT) test, and tensile strength ratio (TSR) test. The findings indicate that the 25% bottom ash-modified mixture demonstrated improved performance across multiple parameters. The HWT test showed enhanced rut durability, with a recorded depth of 7.56 mm compared to 8.9 mm for the control mixture. The Cantabro test results revealed lower weight loss percentages for the modified mixture, indicating better abrasion resistance. The dynamic modulus test indicated higher resilience and stiffness in both high- and low-frequency stages. The TSR test highlighted improved moisture resistance, with higher TSR values after 10 wet-drying cycles. These improvements are attributed to the fine particle size and beneficial chemical composition of bottom ash, which enhance the asphalt mixture's density, binder-aggregate adhesion, and overall durability. The results suggest that incorporating 25% crushed bottom ash as a filler in polymer-modified asphalt concrete mixtures is a viable and sustainable approach to improving pavement performance and longevity.