Multiscale mechanistic analysis and graded regeneration strategy for aging degradation of high-content rubber-modified asphalt

This study investigated the aging degradation mechanisms and regeneration efficiency of high-content rubber-modified asphalt (HCRMA, ≥23% crumb rubber content). The analysis revealed the four-component evolution and functional group responses of asphalt with 20, 25, and 30% rubber content at different aging stages. The blending regeneration effects on macro-micro properties were systematically evaluated for the 30% system. Three key discoveries emerged: (1) Dose-dependent component evolution was observed, where the high-content CR system exhibited more significant asphaltene accumulation post-PAV aging compared to lower-content systems, with the degree of accumulation positively correlated with rubber content. (2) FTIR analysis revealed that thioether oxidation (C-S → S = O) and styrene-butadiene rubber (SBR) crosslinking dominated the aging mechanisms, accompanied by substantial increases in carbonyl index (CI) and sulfoxide index (SI).(3) Blending regeneration achieved excellent viscosity recovery for short-term aging but limited recovery for long-term aging, which was attributed to the accumulation of unswollen particles. Micro-mechanism analysis indicated sulfide stabilization governed short-term regeneration, while ester cleavage was critical for long-term recovery.