Search Results (178)

Traffic noise is one of the main sources of environmental problems and a growing challenge for national traffic authorities. It is widely accepted that tire-pavement interaction is the main cause of traffic noise at speeds between 40 and 90 km/h. Typically, noise attenuation strategies include earthworks, tree belts, or noise barriers. However, a solution that is almost always viable is the use of low-noise pavements, which are characterized by their porous macrotexture, such as Stone Mastic Asphalt (SMA) mixtures. These mixtures are increasingly used for heavy traffic volumes because of their many advantages, including drainage properties and mechanical strength. Based on the experimental results obtained on different roads in southern Spain, this paper compares noise reduction in an SMA standard mixture due to the incorporation of different additives, such as crumb rubber and polymeric additives. According to the analysis, increasing the additives content by 1% reduces CPX by 1.18 decibels, approximately, and none of the analyzed sections shows increases greater than 3 dB within 24 months. Additionally, the paper proposes design recommendations regarding macrotexture and the percentage of voids for zones with warm, dry climates, such as Mediterranean Spain. Full article

This study investigated the noise reduction performance of porous asphalt concrete (PAC) pavement under tire–pavement coupling conditions, addressing the limitations of field measurements and laboratory testing. First, tire excitation amplitude parameters were determined based on vibrational contact operational scenarios. Then, finite element simulations were conducted to systematically analyzing the tire–pavement coupling noise characteristics of PAC pavement. The results indicate that PAC pavement effectively reduces the air pumping noise due to its highly porous internal structure, leading to significant noise attenuation. Furthermore, the study examined the key factors influencing the tire–pavement coupling noise in PAC pavement. When maintaining constant vehicle parameters (300 kg load, 60 km/h speed), pavement thickness became the critical noise-control variable, achieving minimum vibration at 6 cm surface layer thickness. Additionally, tire tread depth (5–17 mm) and mold release angle (0–30°) had a more pronounced impact on the air pumping noise compared to groove width (20–60 mm). Increasing the mold release angle and reducing tread depth effectively mitigated the air pumping noise. However, the tire–pavement coupling noise in PAC pavement increased considerably with increasing vehicle speed and load. Particularly, as the speed increased from 30 km/h to 60 km/h, the growth of the air pumping noise was most pronounced, revealing an acoustic transition of tire–pavement coupling noise from vibration-dominated to air-pumping-dominated mechanisms. Full article

To address the technical bottleneck of the coordinated improvement of high-temperature rutting resistance, low-temperature cracking resistance and environmental protection performance of road asphalt, and to address the existing problems in the research of sepiolite modified asphalt, such as the ambiguous microscopic mechanism of action, the lack of quantitative relationship between dosage and performance, and the unclear adaptability of modification processes, this study employed high-purity sepiolite as a modifier. After optimizing its microstructure through organic and surface modification, the sepiolite with the best compatibility with asphalt was selected. Four dosage gradients of 2%, 4%, 6%, and 8% were designed. Rheological tests were conducted to investigate the effects of sepiolite on the rutting resistance at high temperature, the cracking resistance at low temperature, and the fatigue durability of asphalt. Gas chromatography–mass spectrometry (GC–MS) was used to analyze changes in the organic components of asphalt fumes, while Fourier-transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) were applied to reveal the microscopic interaction mechanisms and smoke-suppression principles. Results show that pristine sepiolite exhibits the best compatibility with asphalt. Although modified sepiolite shows a 43–45% increase in specific surface area, the overall high–low temperature coordination of the modified asphalt decreases by 10–15%. The sepiolite dosage has a significant influence on asphalt performance: when the dosage is 4–6%, the rutting factor of asphalt increases by 25–30%, indicating the best high-temperature deformation resistance; at 4%, the asphalt creep stiffness decreases by over 15%, minimizing the low-temperature cracking risk; and at 2–4%, the fatigue life extends by 9–13%, with the most notable improvement at 2%. In terms of smoke suppression, the porous structure of sepiolite adsorbs 3–5% of the light volatile components in asphalt, while its metal oxides inhibit the release of aliphatic and aromatic hydrocarbons, reducing toxic fume emissions by 12–18%. Microscopically, the interaction between sepiolite and asphalt is dominated by physical adsorption without chemical functional group recombination. The fibrous network of sepiolite enhances the structural stability of asphalt, while the adsorption of small and medium molecular components optimizes the molecular weight distribution, achieving a dual effect of performance enhancement and smoke suppression. Full article

This study presents a modification strategy to fabricate core–shell composite aggregates from reclaimed asphalt pavement (RAP), aligning with green chemistry principles for waste valorization. The method involves creating a porous cementitious shell on the surface of RAP particles through a controlled hydration process. This surface modification simultaneously addresses the inherent structural weaknesses and irregular morphology of raw RAP, enabling the design of materials with desired properties. A face-centered central composite design (FCCD) was employed to optimize the synthesis process, elucidating the nonlinear relationships between key synthesis parameters and the final material characteristics. The optimized synthesis yielded porous aggregates with significantly enhanced structural integrity, evidenced by a 43.9% reduction in crushing value. Furthermore, the surface modification effectively regulated the material’s morphology and particle size distribution, leading to a 3.6 mm increase in median particle size (D₅₀) and a 27.69% decrease in the content of fines (<4.75 mm). Microstructural characterization confirmed the formation of a rough, porous cementitious shell composed of hydration products, which provides the structural basis for the material’s enhanced performance. This work establishes a clear structure–property relationship, demonstrating a new pathway for the rational design and synthesis of functional porous materials from solid waste for application in high-grade pavements. Full article

To enhance the performance of reclaimed asphalt pavement and evaluate its suitability under severe environmental conditions, this study systematically assessed the reinforcing effects of two modifiers: styrene–butadiene rubber (SBR) and polyurethane (PU). The stability and mechanical properties of mixtures with varying recycled asphalt contents were tested, with a focus on the effects of water immersion and high-temperature (150 °C) aging. The underlying mechanisms were elucidated using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). Results indicate that recycled asphalt incorporation significantly degraded the mixture’s performance; stability and mechanical strengths decreased with recycled asphalt content following a cubic function, with maximum deterioration rates of 37.3%, 67.2%, 73.6%, and 72.1%. Water and thermal aging further accelerated performance decay, with deterioration rates reaching up to 61.2% and 63.9%, respectively. Modifiers effectively counteracted this trend: SBR and PU enhanced the aforementioned properties by up to 102.6%, 50%, 60.3%, and 56.9% and 139.5%, 81.4%, 113.2%, and 120.3%, respectively. Microstructural analysis revealed that RAP led to decreased C and O contents, increased Si and Fe presence, and a more porous structure. In contrast, the modifiers increased binder content and interfacial density. This research provides a theoretical foundation and technical pathway for the engineering application of high-performance recycled asphalt mixtures in complex environments. Full article

Tin-based materials have emerged as promising anode candidates for advanced lithium-ion batteries (LIBs) due to their high theoretical capacity (e.g., 994 mAh·g⁻¹ for Li₄.₄Sn), moderate operating potential, and natural abundance. However, Tin-based materials suffer from severe volume expansion (>300%) and rapid capacity decay during cycling. To mitigate these challenges, a composite composed of tin-based materials and porous carbon (PC), i.e., SnO₂/SnS₂@PC, was prepared by calcining a mixture of SnO₂, petroleum asphalt and calcium carbonate at high temperature, where petroleum asphalt acted as the carbon and sulfur resource, and calcium carbonate acted as a pore-forming template. The prepared SnO₂/SnS₂@PC composite had a specific surface area of 190 m²·g⁻¹ with total pore volume 0.386 cm³·g⁻¹, and delivered an initial specific capacity of 1431 mAh·g⁻¹ and retained 722 mAh·g⁻¹ at 100th cycle at 0.2 A·g⁻¹, which is nearly three folds that of the actual capacity (~260 mAh·g⁻¹) of commercial graphite. The novelty of this work lies in that the abundant sulfur element in petroleum asphalt was fully utilized to react in situ with nano SnO₂ to generate SnS₂ and form a composite with high specific capacity and good structural stability, along with greatly reducing the emission of the harmful element sulfur into the atmosphere. Full article

Asphalt mixtures designed with an elevated air void content are intended to lower traffic noise as well as to improve traffic safety and quality by improving rainwater evacuation through the layer of the surface mixture, not just on top of it. While undoubtedly mixtures with high air voids have significant advantages, the durability of such mixes could be an issue. In the research presented in this paper, a performance evaluation case study of asphalt mixes with medium and high air void content was investigated, in both the laboratory and the trial section. The study assessed asphalt mixtures intended for so-called quiet pavements in terms of selected properties (such as water and frost resistance, low temperature cracking, fatigue life, and water permeability) that significantly impact the durability of the pavement surface course under traffic loads and climatic conditions. Five different mixtures were designed, which differed in the proportion of individual components, grain size, asphalt content, and void content. The conducted research indicates that mixtures with increased void content may exhibit lower durability parameters. In addition, the surface drainage performance can be effectively managed by selecting the appropriate mixture type, maximum aggregate size, and target air void content, depending on the functional requirements for macrotexture and pavement type. This should be considered both in the mix design process, by using the best possible materials and conducting additional testing, and also when selecting the mixture type to find an optimum between durability and acoustic parameters of the pavement layer. Full article

In winter, some roads face the problems of severe rain accumulation and ice formation, which pose major risks to traffic safety and result in substantial economic losses. With the development of hydrophobic materials, hydrophobic coatings have gradually gained attention as a novel anti-icing technology. In this study, utilizing vinyl triethoxysilane (VTES) as the monomer and benzoyl peroxide (BPO) as the initiator, a hydrophobic anti-icing coating for highway pavements was prepared through the free radical polymerization method. Through designing the icing rate test and ice–pavement interface adhesion strength test, combining the contact angle test technology, wet wheel abrasion test, and pendulum friction coefficient test, the anti-icing performance, durability, and skid resistance performance of the hydrophobic anti-icing coating under the three types of mixtures of asphalt concrete (AC-13), Portland cement concrete (PCC), and porous asphalt concrete (PAC-13) were evaluated. The results indicate that when the surface layer of the pavement was sprayed with anti-icing coating, the water was dispersed in a semi-spherical shape and easily rolled off the road surface. Compared to uncoated substrates, the anti-icing coating reduced the icing rate on the surface by approximately 25%. Comparing with the uncoated pavements mixtures, for AC-13, PCC, and PAC-13 pavements, the ice–pavement interface adhesion strength after the application of hydrophobic anti-icing coating reduced by 30%, 79% and 34%, respectively. Both cement pavements and asphalt pavements, after the application of hydrophobic anti-icing coating, expressed hydrophobic properties (contact angle of 131.3° and 107.6°, respectively). After wet wheel abrasion tests, the skid resistance performance of pavement surfaces coated with the hydrophobic anti-icing coating met the specification requirements. This study has great significance for the promotion and application of hydrophobic anti-icing technology on highway pavements. Full article

Due to the increasing volume of traffic on the world’s highways, researchers have been searching for new composite techniques and methods to develop durable and cost-effective pavement structures. The semi-rigid pavement is a composite pavement consisting of a porous asphalt mix with air voids between 25 and 30% and a high-fluidity cementitious grout. In this study, different cementitious grout mixes were prepared. Then a porous asphalt mix with almost 30% air void content was designed. After evaluating the workability, mechanical strength, and volume stability of the prepared grout mixes, the most suitable mix is proposed to fill the voids in the porous asphalt mix. Finally, the prepared semi-rigid pavement specimens were subjected to various tests to evaluate the performance characteristics of the designed pavement. The research concludes that the grout mixture ratio proposed in this study has good grouting ability and the semi-rigid pavement has superior performance characteristics. Full article

To evaluate the feasibility of a virtual overlay tester (OT), a modeling approach was proposed based on the discrete element method (DEM). Simulations were conducted on three types of asphalt mixtures across three different thickness conditions. Through the analysis of the load/displacement curves, crack propagation paths, force chains, and contact force characteristics, it was observed that the peak loads decrease with increasing thicknesses, indicating a notable size effect. The complexity of the crack path was positively correlated with the particle size along the path and the fractal dimension. Coarse aggregates can inhibit crack propagation to some extent. Prior to reaching the peak load, compressive force chains in asphalt concrete-13 (AC13) and large stone porous asphalt mixture-30 (LSPM30) exhibited a symmetrical and divergent distribution along the crack, while tensile force chains formed an arch-like pattern. After the peak load, compressive force chains were symmetrically distributed in an arch shape along the crack. In stone mastic asphalt-13 (SMA13), compressive forces were transmitted along coarse aggregates, forming several continuous vertical paths. The proportion of strong compressive force chains to total compressive force chains across the three gradations ranged from 0.74 to 0.83, while the corresponding proportion for tensile force chains ranged from 0.72 to 0.78. Full article

This study investigates the permeability performance and engineering performance of porous asphalt concrete (PAC) mixtures. PAC-10 and PAC-13 mixture specimens with various porosities were prepared. The relationships among porosity, effective porosity, and effective porosity proportion were analyzed, and the pavement engineering performance was evaluated. Moreover, the effects of nominal maximum aggregate size (NMAS) and porosity characteristics on the permeability coefficient were also examined. The results indicate that both the effective porosity and the effective porosity proportion increase with total porosity for both the PAC-10 and PAC-13 mixtures. PAC-13 consistently exhibits a higher effective porosity than PAC-10, suggesting enhanced drainage performance. The designed PAC mixtures satisfy the requirements of high-temperature stability and moisture resistance for asphalt pavements, while the large porosity is contradictory with high-temperature stability and moisture resistance. Additionally, the permeability coefficient significantly increases with larger NMAS, and a strong linear correlation is observed between permeability and both total and effective porosity, where the coefficient of determination (R²) is larger than 0.9. These findings demonstrate that porosity parameters can serve as reliable indicators for assessing the permeability performance of PAC mixtures with different gradations. Full article

Polymer-modified bitumen is difficult to produce and often separates during storage and transport. In contrast, granular bitumen modifiers offer wide applicability, construction flexibility, and ease of transport and storage. This study involved preparing a multipolymer granulated bitumen modifier with a styrene–butadiene–styrene block copolymer, polyethylene, and aromatic oil. To elucidate the modification mechanism of a multipolymer granulated bitumen modifier on bitumen, the elemental composition of bitumen A and B, the micro-morphology of the modifiers, the changes in functional groups, and the distribution state of the polymers in the bitumen were investigated using an elemental analyzer, a scanning electron microscope, Fourier-transform infrared spectroscopy, and fluorescence microscopy. The effects of the multipolymer granulated bitumen modifier on the physical, rheological, and viscoelastic properties of two types of base bituminous binders were investigated at various dosages. The test results show that the Z_H/C ratio of base bitumen A is smaller than that of base bitumen B and that the cross-linking effect with the polymer is optimal. Therefore, the direct-feed modified asphalt of A performs better than the direct-feed modified asphalt of B under the same multipolymer granulated bitumen modifier content. The loose, porous surface structure of styrene–butadiene–styrene block copolymer promotes the adsorption of light components in bitumen, and the microstructure of the multipolymer granulated bitumen modifier is highly coherent. When the multipolymer granulated bitumen modifier content is 20%, the physical, rheological, and viscoelastic properties of the direct-feed modified asphalt of A/direct-feed modified asphalt of B and the commodity styrene–butadiene–styrene block copolymer are essentially identical. While the multipolymer granulated bitumen modifier did not significantly improve the performance of bitumen A/B at contents greater than 20%, the mass loss rate of the direct-feed modified asphalt of A to aggregate stabilized, and the adhesion effect reached stability. Image processing determined the optimum mixing temperature and time for multipolymer granulated bitumen modifier and aggregate to be 185–195 °C and 80–100 s, respectively, at which point the dispersion homogeneity of the multipolymer granulated bitumen modifier in the mixture was at its best. The dynamic stability, fracture energy, freeze–thaw splitting strength ratio, and immersion residual stability of bitumen mixtures were similar to those of commodity styrene–butadiene–styrene block copolymers with a 20% multipolymer granulated bitumen modifier mixing amount, which was equivalent to the wet method. The styrene–butadiene–styrene block copolymer bitumen mixture reached the same technical level. Full article

In order to investigate the influence of different tire textures, pavement types, and vehicle parameters on the tire/road noise level and its spectrum characteristics, 19 kinds of asphalt pavement main structures of RIOHTrack full-scale test track were tested by the close-proximity trailer (CPXT) tire/road noise detection method. Considering investigated parameters such as tire texture, vehicle speed, and trailer axle weight, and relying on multi-functional road condition rapid detection vehicle and laboratory tests to collect a variety of road surface information and material parameters, a multiple-linear-regression model of tire/road surface noise level of RIOHTrack (Research Institute of Highway Full-scale Test Track) asphalt pavement was constructed. Finally, the causes of noise level differences among different influencing factors were further analyzed through spectrum characteristics. The results show that vehicle speed is the most important factor affecting tire/road noise. The noise level of different tires varies due to different textures, but the noise level among different trailer axle weights is roughly the same. Vehicle speed (v), FWD center deflection (D₀), surface asphalt mixture air voids (VV), sensor-measured texture depth (SMTD) and international roughness index (IRI) were selected to establish the noise prediction models of different tire textures. Noise spectrum analysis shows that the spectrum of different vehicle speeds is significantly wide in the full frequency range, and the spectrum variation of differently textured tires is mainly concentrated in a certain range of the peak frequency. The noise spectrum curve of porous asphalt concrete (PAC13) is significantly lower than that of other asphalt mixtures in the full frequency range above 800Hz, indicating a greater noise reduction effect. Full article

Traffic-induced noise pollution is a significant environmental issue, driving the development of advanced noise-reducing pavement materials. Semi-dense graded asphalt mixtures (SDAMs) present a promising compromise, offering enhanced acoustic properties compared to conventional dense-graded asphalt mixtures while maintaining superior durability to porous asphalt mixtures. However, the mechanism underlying the relationship between the energy dissipation characteristics and noise reduction effects of such mixtures remains unclear, which limits further optimization of their noise reduction performance. This study designed and prepared semi-dense graded noise-reducing asphalt mixtures SMA-6 TM, SMA-10 TM, and SMA-13 TM (SMA TM represents noise-reducing SMA mixture) based on traditional dense-graded asphalt mixtures SMA-6, SMA-10, and SMA-13, and conducted tests for water stability, high-temperature performance (60 °C), and low-temperature performance (−10 °C). Subsequently, energy loss parameters such as loss factor and damping ratio were calculated through dynamic modulus tests to characterize their energy dissipation properties. The mechanism linking the energy dissipation characteristics of semi-dense graded asphalt mixtures to noise reduction was investigated. Finally, the noise reduction effect was further verified through a tire free fall test and a close-proximity (CPX) method. The indoor test results indicate that the semi-dense mixtures exhibited a trade-off in performance: their dynamic stability was 11.1–11.3% lower and low-temperature performance decreased by 4.2% (SMA-13 TM) to 14.1% (SMA-6 TM), with moisture stability remaining comparable. Conversely, they demonstrated superior damping, with consistently higher loss factors and damping ratios. All mixtures reached peak damping at 20 °C, and the loss factor showed a strong positive correlation (R² > 0.91) with energy dissipation. Field results from a test section showed that the optimized SMA-10 TM mixture yielded a significant tire–road noise reduction of 3–5 dB(A) relative to the SMA-13, while concurrently meeting key performance criteria for anti-water ability and durability. This study establishes a link between the energy dissipation in SDAM and their noise reduction efficacy. The findings provide a theoretical framework for optimizing mixture designs and support the wider application of SDAM as a practical noise mitigation solution. Full article

Urban waterlogging due to sudden rainfall leads to critical issues. This study aims to develop sustainable porous asphalt pavement by incorporating different proportions of recycled coarse aggregate. Recycled coarse aggregate from waste laboratory-tested concrete in 19, 12.5, and 9.5 mm sizes was prepared for a porous asphalt mix series (Mix-Types 1-9). The study showed that optimal aggregate ratios performed well in porous asphalt mixes. Mix-Type-3 with the aggregate ratio of 19:12.5:9.5 mm (1:1:0.5) achieved an optimal stability of 8.88 kN at the minimum flow rate. The movement of water flow results revealed that permeability decreases with time. The Mix-Type-3 permeability reductions were found to be 16.75% and 30.14% at 6 and 12 months, compared to the permeability of fresh mixes. The study results revealed that the Mix-Type-3 retained the highest stability level, and the permeability fell within the standard values. Hence, it is concluded that Mix-Type-3 balances in all parameters and is a viable choice for effective and sustainable urban water management. Full article