Study on the mechanism of time gradient pressure aging of crumb rubber modified asphalt

Crumb rubber modified asphalt (CRMA) is widely used in pavement engineering due to its superior performance. However, the aging mechanism of CRMA has not yet been fully elucidated. There is a lack of standardized classification for long-term aging stages, and the understanding of performance thresholds of CRMA at various aging stages remains unclear. This study employed time-gradient pressure aging (PAV 5-30 h) to simulate the evolution of CRMA (prepared by wet process) during typical long-term laboratory aging periods, systematically evaluated the variations in its performance across these aging stages, and investigated the changes in typical functional groups and interfacial compatibility via Fourier transform infrared spectroscopy and fluorescence microscopy. Integrated rheological analysis revealed the aging mechanism as a coupled process of “crosslinked network evolution – chemical composition transitions – interfacial interaction dynamics.” Key findings demonstrated that unaged CRMA primarily exhibited physical reinforcement; short-term aging enhanced elasticity through interfacial optimization; long-term aging progressed through swelling, de-crosslinking, and degradation, with PAV20h as the critical threshold for performance deterioration. This study systematically elucidates the aging mechanism of CRMA, establishes a four-stage aging framework, and elaborates on the effects of aging on the properties of crumb rubber modified asphalt, thereby providing reference value for the performance evaluation and service life prediction of this material.