Properties Of Asphalt Research Articles

Investigation of Adhesion and Stripping Properties in Asphalt–Aggregate Systems: Impact of NaCl Solubility and Freeze–Thaw Cycles

Investigation of Adhesion and Stripping Properties in Asphalt–Aggregate Systems: Impact of NaCl Solubility and Freeze–Thaw Cycles

Assessing pavement characteristics: An in-depth evaluation of waste engine oil and Buton rock asphalt composite modified asphalt and its mixture

To investigate the cooperative influence of waste engine oil (WEO) and Buton rock asphalt (BRA) on asphalt characteristics, the WEO/BRA composite modified asphalt and its mixture with varied dosages were prepared. The high-, moderate-, and low-temperature assessments of WEO/BRA composite modified asphalt were conducted through temperature sweep tests, multiple stress creep and recovery (MSCR), and bending beam rheometer (BBR) tests. The softening point difference was used to analyze the storage stability of composite modified asphalt. Based on the Fourier transform infrared spectroscopy (FTIR) and fluorescence microscope (FM) test, the microscopic feature and chemical constitution of WEO/BRA composite modified asphalt were analyzed. Rutting test, low-temperature bending test, immersed Marshall test, freeze-thaw splitting test, and four-point fatigue bending test were carried out to verify the pavement properties of the WEO/BRA composite modified asphalt mixture. The results indicated that WEO improved the capability in low-temperature conditions and fatigue properties of asphalt modified with BRA. BRA enhanced the high-temperature property of asphalt modified with WEO. The synergistic effect of WEO, BRA, and neat asphalt was a physical reaction, and these modifiers were uniformly distributed in the asphalt. Meanwhile, WEO/BRA composite modified asphalt had excellent storage stability for the single modified asphalt. The test results of the asphalt mixture verified the results, indicating that WEO/BRA composite modified asphalt can be considered a new green and durable asphalt pavement material.

Enhancing mechanical properties of hot mix asphalt with olive kernel ash: A sustainable modifier

The use of agricultural waste as a sustainable modifier with functional and environmental advantages has grown appealing. While conventional modifiers offer several benefits, utilizing biological modifiers generated from agricultural resources like ash can be more effective in both technical and economic aspects. This study examines the performance of hot mix asphalt (HMA) containing modified bitumen with olive kernel ash (OKA) collected from an olive canning factory. To accomplish this goal, the modified bitumen was subjected to kinematic viscosity testing and Fourier-transforms infrared spectroscopy (FTIR) analysis to assess its chemical characteristics. Additionally, the following tests were performed on HMA: Marshall, resilient modulus, indirect tensile strength, repeated load axial creep, and semicircular bending test. Research findings reveal that the addition of 20 % OKA increases the resistance to rutting by more than 1.3 times. This is attributed to the stiffening capabilities and high density of OKA within the bitumen mixture. Reducing the moisture sensitivity of the modified mixtures, especially in the samples containing 10 % OKA, is attributed to the reduction of air voids and the improved bonding between the bitumen and aggregate. This is due to the OKA's more absorbent and reactive surface. Furthermore, fatigue analysis at intermediate temperatures showed that limiting the OKA dosage to 5–10 % can increase resistance to fatigue cracking by 11 %. Additionally, incorporating OKA at 5 % and 10 % doses into modified asphalt mixtures significantly improves fracture energy and stress intensity factors by up to 24 %. However, when the OKA dosage exceeds 10 %, a decline in performance is observed at low temperatures. In summary, according to the desired performance and workability, OKA is considered a viable alternative for bitumen modification with technical, economic, and environmental goals.

Damaging effect of fine grinding treatment on the microstructure of polyurea elastomer modifier used in asphalt binder

The excellent elasticity and strength of polyurea elastomer could provide good potential in asphalt modification. In this paper, PUA materials were prepared by spraying and crushing technology. Using liquid nitrogen, PUA was ground into powders of different particle sizes. The size composition and characteristics of PUA powder were analyzed using laser particle size analyzer. The functional microstructures were identified through laser confocal scanning microscopy. The damaging effect of grinding on functional microstructures was investigated. The impact of PUA on the rheological property of asphalt was determined. The results showed that the size distribution of PUA powders presents the normal distribution characteristic, and the size distribution of 0.3 mm, 0.15 mm, and 0.075 mm PUA powders have intersection. The spherical microstructure distributed independently in PUA particle and some spherical microstructure distributed in the triangular shape. The width/length ratio of characteristic microstructure in 0.15 mm and 0.075 mm PUA powder were increased, which supposed that the spherical microstructure had been damaged by grinding effect. PUA could reduce the cumulative deformation of asphalt when suffering from repeated loads.

The effect of ultraviolet radiation on asphalt functional group through FTIR and EW method

Ultraviolet (UV) ageing is an important factor affecting the service performance of asphalt pavement. However, at present, the group transformation of asphalt under ultraviolet radiation is still need to be studied. The ageing mechanism of asphalt could be better revealed through studying the functional groups of asphalt. In this study, asphalt were aged by three kinds of ultraviolet light. The changes of characteristic functional groups of asphalt before and after ultraviolet ageing were analyzed by infrared spectroscopy. Finally, the entropy weight method was used to calculate the count of inter conversion. The results showed that the carbonyl index of asphalt increased after ultraviolet ageing, while the methylene index, aromatic index, aliphatic index, and sulfoxide index decreased. After the asphalt is aged by ultraviolet, the C-C, C-H and C=C bonds in the asphalt material will be converted to C=O, and S=O will be converted to SO2. The results could be used to simulate asphalt molecules in order to better understand the performance and properties of asphalt.

Toward understanding the surface morphology and microscopic mechanical properties of asphalt after experiencing tensile and compressive stress

Load-induced stress is a one of the major causes of asphalt pavement failure. It is, therefore, necessary to understand the changes in stress on the microscopic mechanical properties of asphalt in improving pavement design. While much research been carried out concerning effects brought about by tensile, the effects that compressive stress would have on the microscopic mechanical properties of asphalt remains less explored. In the current study, a custom-designed tension–compression device was developed and atomic force microscopy (AFM), complemented by molecular dynamics (MD) simulations, to investigate the microscopic properties of asphalt in both undeformed and deformed states. The findings reveal that asphalt exhibits significantly weaker compressive strength compared to tensile strength. Under tensile stress, the various components in asphalt align loosely in the direction of tension, while asphaltenes are affected the least. These changes in apparent morphology reflect different migration rates of the various components. Under compressive stress, the asphalt surface is more compact, and this reduces the area of the “bee” structure. Under varying stress conditions, asphalt exhibits a smoothing of the rough region with an associated loss in adhesion. Specifically, increased tensile strain leads to smoother topography and increased adhesion, while increasing compressive strain has the opposite effect. These results provide valuable theoretical insights for the design and maintenance of more durable asphalt pavements.

Research on the Rheological Properties and Modification Mechanism of Epoxy Resin/SBS Composite-Modified Asphalt

Both epoxy resin (ER) and SBS are considered effective pavement materials for avoiding ruts. However, epoxy resin asphalt suffers from poor low-temperate performance and a high material cost in practical applications. Aiming to tackle these issues, a new type of composite asphalt modifier (ER-SBS) has been fabricated by combining epoxy resin with SBS. This work prepared modified asphalt with different doping amounts using the above composite asphalt modifier (ER-SBS), intending to explore the properties of composite-modified asphalt and the modification mechanism of the modifier. Furthermore, the effects of the composite modifier at different doping amounts on the viscoelastic property of asphalt were explored through rheological tests, and then the prepared composite-modified asphalt was compared with matrix asphalt and SBS-modified asphalt. In addition, the modification mechanism of the composite modifier was investigated by fluorescence microscopy and infrared spectroscopy. The difference in pavement performance between the composite-modified asphalt and SBS-modified asphalt was compared by a rut test and dynamic modulus test. The research results showed that the composite modifier improved the high- and low-temperature performances and viscoelastic property of matrix asphalt. When the doping amount was raised to 9%, the composite-modified asphalt exhibited better a modification effect than SBS-modified asphalt. The rut test results indicated that composite-modified asphalt demonstrated a stronger deformation resistance than SBS-modified asphalt. The dynamic modulus test showed that the composite-modified asphalt has better viscoelastic properties and temperature sensitivity. Fluorescence microscopy suggested that the crosslinking between the composite modifier and asphalt forms a mesh structure which greatly improves its resistance to deformation. From infrared spectroscopy, the composite modifier clearly functions as a physical modifier.

Study on preparation and properties of GA/h-BN modified road petroleum asphalt based on ball milling method

ABSTRACT Graphene (GA), a two-dimensional nanomaterial, is noted for its exceptional mechanical, thermal and electrical properties. The integration of GA with road materials can potentially develop high-performance composite road materials. However, its application in road engineering is limited by complex preparation processes and high costs. This paper presents a GA/h-BN composite material developed through mechanical stripping using flake graphite and hexagonal boron nitride (h-BN). A mathematical model was created employing uniform design methods and optimised through numerical analysis to identify the optimal process parameters. Microscopic techniques, including X-ray diffraction and atomic force microscopy, confirmed that the GA/h-BN product consists of approximately three layers, forming a ‘graphene-hexagonal boron nitride-graphene’ nanolayer structure. The composite was then used to modify matrix asphalt, with performance tests determining the optimal dosage. The results indicated that adding 0.3% GA/h-BN significantly improved the asphalt's high- and low-temperature performance, fatigue resistance and cracking resistance. Moreover, the evaluation of the physical properties of matrix asphalt modified solely with h-BN revealed that, despite h-BN comprising 70% of the mass fraction in the GA/h-BN modifier, it exerted a minimal impact on the performance of the asphalt. This study introduces a novel source of raw materials for the application of GA in road engineering.

Performance of natural asphalt as a paving material: A laboratory and field evaluation

The ever-growing need to build roads to meet the necessary transportation demands is challenging, especially for developing countries. Low-volume roads (LVRs) are usually the backbone of catalyzing economic growth in these countries. With impediments surrounding Petroleum bitumen (price fluctuations) and environmental concerns, scientists are putting their effort into finding an alternative. The presented research is an attempt to check if Natural asphalt can be used as a full or partial replacement of the Petroleum bitumen. To the best of the authors' knowledge, only limited studies have focused on characterizing and understanding the engineering properties of Natural asphalt. The available techniques do not provide reliable information to the road authorities and hence they are discouraged from using it in practice. Particularly for countries, where the Natural asphalt source is available, the overall dependence on importing the Bitumen could be substantially reduced. Empirical and experience-based design criteria may not be sufficient as the standards were never developed for such materials, hence, a scientific approach is required before bringing it into practice. In this research, Natural asphalt sourced from different locations in Nigeria was assessed. Before performing the mixture level tests using Marshall and Cantabro design methods, the rheological and fatigue properties of the extracted Natural bitumen were examined in the laboratory. In the design of the experiment, various percentages of Natural asphalt were added between 0 % and 20 % by total mix weight; implying that the remaining required fraction of binder was fulfilled by the addition of petroleum bitumen. By using a ranking system (supported by statistics), an optimal design of mixture was obtained which was used in the field (exposed to normal traffic) at 30 different sections. Overall, results showed a good correlation between laboratory and field performance as compared to the petroleum-based mixture which was used as a reference mixture

Influence of Variable Intensity Ultraviolet on the Performance of SBS Modified Asphalt

Previous scholars studied UV aged asphalt performance under constant UV intensity. This study proposed a method of UV aged asphalt based on the time-varying UV intensity, which is more capable of realistically simulating the UV aging of asphalt under natural conditions. The softening point, viscosity, and DSR tests were used to analyze changes in conventional and rheological properties of UV aged asphalt and compared them with RTFO (Rolling Thin-Film Oven) aged asphalt. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) tests were analyzed for the microscopic characteristics. The aging index was also used to evaluate the percentage of asphalt aging attributable to each UV aging cycle. The results show that the softening point is more susceptible to UV radiation, with UV-6 cycles exceeding the softening point increment of RTFO. On the contrary, the viscosity is more susceptible to thermo-oxidative aging, and the viscosity increment of RTFO is 39.3% higher than that of UV-12 cycles. Based on DSR's test results, the rutting factor magnitude of RTFO was between 9-12 UV aging cycles The phase angle results indicate that thermo-oxidative aging is more likely to convert asphalt to elastomer than RTFO asphalt. UV aging process of asphalt produced sulfinyl and, carbonyl and other polar functional groups, asphalt intermolecular forced to enhance the production of a harder oxidation layer, the asphalt surface began to appear cracks. As aging time increases, the cracks become longer and deeper. Practical image recognition technology can identify the areas of the cracks. The crack area follows a linear pattern during cycles 3 to 9, while the growth rate slows down during cycles 9 to 12.

Study on the low-temperature performance of chemically cross-linked polyethylene composite modified asphalt binder

The great disadvantage of polyethylene modified asphalt in terms of low-temperature performance has led to limitations in its large-scale application. The aim of this study was to investigate whether peroxides and silane coupling agents can significantly improve the low-temperature performance of modified asphalt through chemical cross-linking. Therefore, nine experimental groups were designed through orthogonal experiments, and the low-temperature properties of matrix asphalt, control asphalt, and nine modified asphalt groups were evaluated by using a bending beam rheometer, and microscopic analyses were carried out using FM, SEM, and FTIR tests. The experimental results showed that the 5 °C ductility increased to a maximum of 136.3 % and 166.2 % compared to the matrix asphalt and control asphalt, and the cross-linking between the polymer and the asphalt was enhanced microscopically. Chemical cross-linking of asphalt and polymer using peroxide and silane coupling agent provides a feasible method to expand the application of polymer in pavement engineering.

Study on the Microscopic Mechanism and Performance of TPU/SBR Composite-Modified Asphalt

To enhance the service life of traditional asphalt pavement and mitigate issues such as high-temperature rutting and low-temperature cracking, this study investigates the composite modification of matrix asphalt using thermoplastic polyurethane (TPU) and styrene-butadiene rubber (SBR). Initially, the study examines the conventional properties of the composite-modified asphalt from a macro perspective, analyzing the performance variations of asphalt before and after TPU and SBR modification. Subsequently, microscopic analysis is conducted to explore the microstructure, phase structure, and modification mechanisms of the composite-modified asphalt, with a focus on understanding the underlying reasons for performance changes. The influence of TPU and SBR on asphalt performance is evaluated comprehensively. It is found that TPU-modified asphalt demonstrates superior high-temperature performance, storage stability, and elastic recovery. Conversely, SBR-modified asphalt excels in ductility at low temperatures, though its storage stability decreases with increasing dosage. Based on a thorough analysis of the conventional properties of the two types of modified asphalt, the optimal dosages of TPU and SBR are determined to be 15% and 3.5%, respectively. In the composite-modified asphalt, TPU facilitates the even distribution of chemical components, creating a more stable cross-linked network structure. The compatibility of TPU, SBR, and asphalt contributes to the good storage stability of the composite-modified asphalt. While SBR effects physical modification, TPU induces chemical modification of asphalt. Consequently, the composite modification system benefits from both physical and chemical enhancements, resulting in excellent overall performance.

Pemanfaatan Limbah Serbuk Kayu dengan Zat Aditif Anti Stripping Agent Terhadap Uji Durabilitas AC-WC (Asphalt Concrete–Wearing Course)

The increasing number of vehicles each year in Indonesia causes excessive repetition of loads that occur on road pavements, as well as extreme weather changes resulting in damage to the pavement layer, especially at the level of durability, especially in the AC-WC layer. The use of sawdust waste in the AC-WC mixture has met the marshall test values/characteristics, but it is necessary to test its durability; a high durability value indicates that the road is more durable and resistant to weather and water. Therefore, it is necessary to improve the quality of road pavement by adding anti-stripping agent additives at levels of 0.3%, 0.4%, and 0.5% to the AC-WC mixture of 25% wood powder waste substitution in order to improve the properties of asphalt in increasing the coating of asphalt with aggregates in a wet state to produce stronger bonds to extend the life of the road. This study aims to determine the effect of adding anti-stripping agent additives in AC-WC mixtures with sawdust waste on durability tests. Experimental tests were conducted using the research method at the Civil Engineering Laboratory of Diponegoro University Vocational School Semarang. The study results obtained a durability value based on the calculation parameters of the Residual Strength Index (IKS) based on the General Specifications of Bina Marga 2018 (Rev 2), which shows the durability of AC-WC asphalt. The results of marshall testing obtained based on averages include VIM 4.11%, VMA 13.15%, VFA 77.33%, Stability 1893.73 Kg, Flow 2.17 mm and MQ 1070.03 kg/mm from 25% wood powder waste variation with anti-stripping agent additives 0.3%; 0.4%; 0.5% in AC-WC wear layer has met the General Specifications of Bina Marga 2018 (Rev 2). The average durability values of IKS with sequential soaking time are 24 hours 92.24%, 48 hours 88.87%, and 72 hours 80.08%.

Study on the Performance of Modified Qingchuan Rock/Rubber Asphalt

This paper developed a new environmentally friendly composite modified asphalt material and studied the composite modification of Qingchuan rock asphalt (QRA) and waste tire rubber powder (RP) was studied in this paper. QRA/RP composite modified asphalt was prepared by adding these two materials as modifiers into matrix asphalt and compared with matrix asphalt and QRA modified asphalt. The basic properties of asphalt before and after aging were evaluated by the rotating thin film oven test. The high-temperature performance and permanent deformation resistance at different temperatures and frequencies were analyzed by the dynamic shear rheological test. The bending creep stiffness test was used to evaluate the low-temperature performance. In addition, the microstructure and modification mechanism of composite-modified asphalt were analyzed by scanning electron microscopy and infrared spectroscopy. The results show that QRA-modified asphalt is superior to matrix asphalt in terms of mass loss, viscosity ratio, and residual penetration, while QRA/RP composite-modified asphalt is further improved on this basis, QRA/RP composite modified asphalt can effectively improve the high and low temperature performance of asphalt.. Although the addition of RP is mainly based on physical modification, it also causes weak chemical reactions and enhances the adhesion of asphalt. The interaction between Qingchuan Rock asphalt and rubber powder significantly improves the overall stability of asphalt structure.

Research on the Rheological Performance of Fast-Melting SBS-Modified Asphalt under Complex Environmental Factors

Currently, fast-melting SBS (Styrene-Butadiene-Styrene)-modified asphalt is widely used in pavements. However, in practical applications, complex environmental factors accelerate the deterioration of asphalt material properties, significantly affecting the service life of roads during their operational period. This study aims to examine the effects of complex environmental factors, including thermal oxidation, ultraviolet radiation, and various concentrations of salt solutions, on the high and low-temperature rheological properties of fast-melting SBS-modified asphalt (abbreviated as SBS-T-modified asphalt). Pressure aging–ultraviolet aging coupling and pressure aging–ultraviolet aging different concentration salt solution coupling were selected as the aging groups to simulate complex environmental conditions. Additionally, base asphalt and pressure-aged asphalt were used as control groups. The rheological properties of SBS-T-modified asphalt were evaluated using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The results indicate that multiple-factor coupling aging reduces both the high-temperature and low-temperature performance of SBS-T-modified asphalt compared to single-factor aging, although the impact on rheological properties is not consistent across all conditions. After the combined effects of UV aging and pressure aging, the rutting resistance and high-temperature performance of SBS-T-modified asphalt are most severely impacted. However, when coupled with salt-solution aging, the rutting resistance of SBS-T-modified asphalt improves, with the complex modulus increasing by approximately 30%. This indicates that the presence of the salt solution enhances the high-temperature performance of the asphalt. An analysis of the low-temperature rheological properties of SBS-T-modified asphalt based on Burgers model shows that the low-temperature rheological performance of SBS-T-modified asphalt worsens under three-factor coupling aging compared to two-factor or single-factor aging, leading to poorer crack resistance. Notably, after adding salt solutions, the thermal sensitivity of SBS-T-modified asphalt increases significantly, with the ΔTc value decreasing approximately sixfold for every 2% increase in salt concentration.

The effect of anionic emulsifiers’ diversity and manufacturing processes on the stability and mechanical properties of the water-based epoxy-emulsified asphalt

Emulsified asphalt mixtures’ cold mix and paving features facilitate asphalt pavements in fulfilling dual-carbon and energy-saving demands. Anionic emulsifiers can enhance emulsion stability, ensure uniform dispersion of oil and water, possess good decompression viscosity, thickening, and lubricating properties, and maintain good stability under acidic conditions. Nevertheless, anionic emulsified asphalt is restricted in engineering applications due to problems like its storage stability. In this paper, eight anionic emulsifiers and two preparation procedures were chosen for stability tests. Through static tests, storage tests, sieve residue tests, and laser particle size tests, the impacts of emulsifiers on the storage stability and dispersion of asphalt were analyzed. Waterborne epoxy resin exhibits excellent adhesive properties, mechanical properties, chemical resistance, and heat stability. A fluorescence microscope test, static and storage test, laser particle size test, and cementation test were employed to explore the effects of different preparation processes and waterborne epoxy mixing ratios on emulsified asphalt’s storage stability, dispersion stability, and structural stability. The results showed that: (1) the emulsified asphalt prepared with the BWH-02 emulsifier exhibits the best storage stability, and blending with 20% of the waterborne epoxy modifier can notably enhance the bonding properties; (2) the shear strength of the BWH-02 waterborne epoxy emulsified asphalt prepared can reach 1.543 MPa, and the tensile viscosity can reach 0.848 MPa; (3), The emulsified asphalt prepared by the process of modification has better storage stability than that prepared by the side of the emulsification process. Moreover, the storage stability of emulsified asphalt prepared by emulsification and modification is superior to that of the emulsification and modification process. This research provides theoretical and technical support for popularizing and applying cold-mixed cold-paving asphalt mixtures.

Evaluation on the diffusion-fusion properties and interfacial mechanical behavior of virgin and aged asphalt

To investigate the regeneration mechanisms of rejuvenated asphalt mixtures, molecular simulation techniques were employed to research virgin and aged asphalt's fusion characteristics and interface mechanical properties. The blended zone was identified based on relative density distribution, and a molecular-scale calculation method for the Degree of binder Blended (DOB) between virgin and aged asphalt was proposed. Finally, the influence of DOB on the mechanical properties of the asphalt-aggregate interface was evaluated through interface pull-out tests. The results revealed that the proposed molecular-scale DOB calculation method effectively assessed the blending effectiveness between virgin and aged asphalt. Higher degrees of asphalt aging made it more challenging for aged asphalt to fuse with virgin asphalt, while elevated temperatures facilitated diffusion fusion between them. Under tensile loading, initial cracks were primarily initiated from the rejuvenated asphalt's blended zone. This region represented the weakest area within the interface system and was prone to fracture under load. The increase in DOB significantly improved the interfacial properties of recycled asphalt, with the increase in DOB the interfacial tensile strength increased by 4%–14% and the fracture energy increased by 10%–19%. However, this enhancement effect diminished with an increased degree of asphalt aging. At the molecular scale, increasing DOB improved the interface strength and deformation resistance of rejuvenated asphalt. The molecular simulation results provide theoretical guidance for evaluating the fusion degree of aged asphalt in RAP materials and determining the utilization efficiency of aged asphalt.

Polydopamine‐modified black phosphorus/microcapsule composite material used to enhance the solar thermal conversion and self‐healing performance of SBS modified asphalt

AbstractThis study developed UV‐responsive microcapsules to enhance the self‐healing properties of asphalt, addressing the limitations of low survival rates and single‐release mechanisms in current encapsulated rejuvenators. The microcapsules, featuring a urea‐formaldehyde shell embedded with polydopamine‐coated black phosphorus nanosheets (BP/DA) and microalgae bio‐oil as the core, can convert solar energy into thermal energy, promoting proactive self‐healing in asphalt materials. BP/DA expands the microcapsules' light absorption range, enhancing their photothermal conversion efficiency. When incorporated into styrene‐butadiene‐styrene (SBS)‐modified asphalt at a 1.5% dosage, the microcapsules (BP/DA/MC) improved the mechanical properties: ductility increased by 13.7%, softening point rose by 2%, and penetration decreased by 3.3%. The storage modulus (G′) at 46 and 64°C increased by 35.9% and 24.3%, respectively, compared to SBS asphalt. Additionally, the ductility self‐healing rate of BP/DA/MC/SBS asphalt improved by 209.7%, with a healing index (HI) of 78.16%. The microcapsules also demonstrated excellent photothermal conversion, increasing the asphalt's temperature by 22.6% under identical lighting conditions. This research offers a new method for developing intelligent self‐healing asphalt with multi‐mechanism activation, providing theoretical support for future third‐generation microcapsule‐based asphalt with remote‐controlled release and activation response.

Characterizing the Self‐Healing Asphalt Materials: A Neutron Imaging Study

Given the significant role of asphaltic pavement in surface transportation systems, even minor enhancements in asphalt materials hold the potential for cost savings and reduced environmental impacts. The healing properties of asphalt have drawn interest for sustainability, yet much remains unknown about the causes and influencing factors. To leverage self‐healing for extending pavement life, understanding the mechanisms and conditions that stimulate microcrack healing is essential. This study aims to investigate the dynamic progress of microcrack closure in asphalt mastics. The time‐series evolution of crack closure led by self‐healing is tracked by neutron computed tomography, with image processing facilitating volumetric analysis over a 7 h period. The study examines the healing process in mastic samples with three different sand filler contents (10, 20, and 30%). Results show that for all the investigated samples, the healing rate declines exponentially over time, with 100% recovery not achieved after 7 h at room temperature. Filler content‐influenced healing speed and 20% sand demonstrate the best performance. Meanwhile, the healing performance varies within the 10% and 30% groups, depending on initial crack size. Additionally, the study finds that initial crack size influences healing behavior in the samples.

Effect of Moisture on the Fatigue and Self-Healing Properties of SiO2/SBS Composite Modified Asphalt.

Moisture accelerates the degradation of asphalt properties, significantly impacting the service life of roads. Therefore, this study uses simplified viscoelastic continuous damage theory and employs frequency scanning, linear amplitude scanning, and fatigue-healing-fatigue tests with a dynamic shear rheometer. The objective is to investigate the effects of aging time, moisture conditions, and aging temperature on the fatigue and self-healing performance of SBS (Styrene-Butadiene-Styrene block copolymer)-modified asphalt, nano-SiO2-modified asphalt, and nano-SiO2/SBS composite modified asphalt in a moisture-rich environment. The results indicate that nano-SiO2 powder enhances the low-temperature performance of modified asphalt, whereas the SBS modifier reduces temperature sensitivity and increases the recovery percentage after deformation. Compared to SBS-modified asphalt, the deformation resistance of nano-SiO2/SBS composite modified asphalt has increased by about 30%, while nano-SiO2-modified asphalt shows relatively poor deformation resistance. The fatigue performance of SBS-modified asphalt deteriorates under moisture, whereas the addition of nano-SiO2 powder improves its fatigue life. Nano-SiO2/SBS composite modified asphalt exhibits strong self-healing capabilities. Although self-healing can enhance the fatigue life of modified asphalt, moisture inhibits this improvement after self-healing.