Effects of salt solution-aging coupling on viscoelastic, fatigue and self-healing properties of asphalt binder

Asphalt binder pavements in saline regions encounter multifaceted challenges in the high-temperature, high-humidity, and high-radiation settings of summer, significantly impacting pavement durability. This study presents an indoor simulation of a coupled salt solution-aging environment, designed to mirror the climatic characteristics of saline regions. Through meticulous experimentation, the dynamic modulus and phase angle master curves of asphalt binder were meticulously constructed via frequency sweep tests, leveraging the time-temperature equivalence principle. The outcomes revealed notable enhancements in the high-temperature performance of asphalt binder following the combined influence of saline-alkali environments and Rolling Thin Film Oven Test (RTFOT) aging. Conversely, the high-temperature performance experienced a decline subsequent to coupling the saline environment with Pressurized Aging Vessel (PAV) and Ultraviolet (UV) aging. To assess fatigue performance after saline-aging coupling, Linear Amplitude Scanning tests, guided by the viscoelastic continuum damage theory, were conducted. Remarkably, it was found that asphalt binder's fatigue life decayed most rapidly under alkaline salt environments, with the saline setting exerting the most significant influence during PAV aging. Comparative analysis indicated that SBS modified asphalt binder displayed greater resistance to saline effects than the 70# asphalt binder. However, SBS modified asphalt binder exhibited limited advantages in resisting alkaline salt environment action under substantial strain. Evaluation of asphalt binder's self-healing capability, employing fatigue-healing-fatigue tests and guided by the viscoelastic continuum damage theory model, revealed intriguing insights. Aging led to a reduction in the asphalt binder's self-healing ability, with sodium sulfate environments imposing the most substantial hindrance. Surprisingly, the sodium carbonate environment exhibited partial promotion of the asphalt binder's healing efficiency. Furthermore, the fatigue life of the healed asphalt binder exhibited increments, albeit with diminishing increases correlating to deeper salt solution-aging. This comprehensive study elucidates the multifaceted impacts of coupled saline-aging environments on asphalt binder performance. Insights into high-temperature behavior, fatigue resistance, and self-healing dynamics provide valuable foundations for advancing asphalt binder formulations tailored for