Editorial: Asphalt pavement performance under complex service conditions

Editorial on the Research Topic Asphalt Pavement Performance under Complex Service Conditions The performance of asphalt pavements often deteriorates under complex service conditions, as evidenced by reduced mechanical integrity, weakened interfacial bonding, and the emergence of secondary damage. These issues can significantly escalate maintenance costs and undermine operational safety and efficiency. While recent technological advances have improved the durability of asphalt materials, the combined effects of moisture, temperature variations, and traffic loading continue to present substantial challenges to long-term performance. Therefore, the development of advanced testing and characterisation methods tailored to these multifactorial service conditions is essential for uncovering failure mechanisms and extending the service life of asphalt pavements. "Frontiers in Materials" is an internationally recognised journal with high visibility, dedicated to publishing rigorously peer-reviewed studies that cover a wide spectrum of topics in materials science and engineering. The research topic "Asphalt Pavement Performance under Complex Service Conditions" emphasises recent advances and emerging technologies related to asphalt pavement. Specifically, this topic addresses multiscale investigation of asphalt pavement materials, performance evaluation under complex service conditions, and intelligent maintenance of asphalt pavement. (1) Multiscale investigation of asphalt materials: As a typical multiphase composite material, asphalt materials exhibit scale-dependent mechanical properties. Integrating investigations across multiple scales can provide valuable insights and explanations for its failure mechanism. At the microscopic scale, the physical, chemical, and mechanical properties of asphalt binder are governed by the interaction among molecules of varying polarity and size. The effects of Sasobit and Evotherm warm mix agents on Karamay 90# asphalt and Tahe 90# asphalt in Xinjiang were evaluated by using Fourier transform infrared (FTIR) and molecular dynamics simulation. The results showed that Sasobit has good compatibility with Karamay 90# asphalt, while Evotherm has a good modification effect on Tahe 90# asphalt (Hu et al.). Rheological and microscale chemical indicators were proposed to evaluate the ageing extent of polymer-modified asphalt binder, including complex shear modulus |G*| at 52℃, the derivative of creep compliance J′ at -18℃, and the carbonyl index ICA (Chen et al.). At the mesoscopic scale, the adhesive property between aggregates and bitumen directly affects the performance of asphalt mixture. The surface roughness, chemical composition, and surface adhesion properties of limestone were better than those of diabase, which resulted in limestone fine aggregate showing better adhesion performance with bitumen than diabase fine aggregate. It was recommended that diabase coarse aggregate and limestone fine aggregate be used to improve the asphalt-aggregate interface (Zeng et al.). In addition, an innovative asphalt mixture design method based on the binder film thickness (BFT) was developed, which, compared with the conventional Marshall and Superpave methods, may achieve superior rutting resistance and balanced durability while reducing binder content (Khan et al.). At the macroscopic scale, a new method of mineral aggregate gradation optimisation based on the fuzzy analytic hierarchy process and a comprehensive evaluation method was put forward to obtain the optimal gradation for road performance (Zhu et al.). The polyacrylamide (PAM) can significantly enhance the mechanical properties of cement stabilised construction waste slurry under varying moisture contents, with an optimal content of approximately 0.5%, thereby improving unconfined compressive strength, elastic modulus, and shear strength, and providing valuable insights for the resource utilisation of waste slurry (Guo et al.). Overall, by integrating microscopic, mesoscopic, and macroscopic investigations, multiscale research not only deepens the fundamental understanding of the physical, chemical, and mechanical behaviors of asphalt materials, but also provides practical guidance for material modification and mixture design, thereby improving pavement performance and durability. (2) Performance evaluation under complex service conditions: The effective determination of working stress and service performance of asphalt pavement under complex service conditions is fundamental to analysing its failure mechanism. The incorporation of recycled concrete aggregate (RCA) and freeze-thaw cycles had a significant impact on the fatigue performance of asphalt concrete, where increasing freeze-thaw cycles accelerate fatigue damage, while appropriate recycled aggregate content can mitigate strength loss and enhance durability under coupled environmental and mechanical loading conditions (Yan et al.). Salt erosion markedly deteriorated the mechanical strength and drying shrinkage resistance of cement-stabilized macadam. As the salt solution concentration increased, the cement-stabilised macadam transitions from shrinkage to expansion, thereby causing arching distress (Wang et al.). Furthermore, the temperature-load coupling effect had a significant influence on the permanent deformation behavior of steel-concrete composite beam bridge deck pavement, in which thermal stress and repeated loading jointly accelerate rutting development, thereby compromising structural durability and service performance (Yang et al.). In summary, the coupled effects of environmental and mechanical factors exert a critical influence on asphalt pavement performance and should be thoroughly addressed in durability-oriented pavement design. (3) Maintenance materials and schemes: For maintenance materials, SBS/CR-modified asphalt binder with C9 petroleum resin exhibited superior rheological properties and 3D printability, which enhanced its adaptability as a crack filling material by providing improved deformation resistance at high temperatures and flexibility at low temperatures (Niu et al.). For intelligent maintenance, a pavement dynamic monitoring data processing approach based on wavelet decomposition and reconfiguration was proposed, which effectively filters noise and enhances feature extraction, thereby improving the accuracy and reliability of pavement condition evaluation (Shang et al.). Overall, advances in maintenance material development and intelligent monitoring technologies offer promising approaches to improving the effectiveness, reliability, and efficiency of asphalt pavement maintenance. A total of eleven manuscripts were received for possible publication in this special issue. Each manuscript underwent a rigorous, fair, and anonymous peer-review process. The quality and originality of every paper were thoroughly evaluated. Ultimately, all eleven research articles were accepted for publication.