Tracking the Aging-Induced Evolution in Self-Healing Capacities of Asphalt Binder: Microstructure and Rheology Analysis

Asphalt pavement inevitably undergoes aging and deterioration of service performance under atmospheric and solar radiation conditions. This study developed an efficient and durable self-healing asphalt based on the designability of the polymer chemical structure and reversible recombination of covalent bonds. Moreover, the effect of long-term thermal oxidative aging and ultraviolet (UV) aging on self-healing promotion by polymers (PUS) containing dynamic disulfide bonds was investigated through a nonthixotropic evaluation system. Subsequently, the reasons for the changes in self-healing capacities of PUS-modified asphalt (PUS-MA) and PUS/styrene butadiene styrene block copolymer-modified asphalt (PUS/SBS-MA) after aging were analyzed from the perspectives of microstructure and rheology using fluorescence microscopy, Fourier transforms infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and dynamic shear rheometer (DSR). The results showed that UV aging is an unfavorable factor for the self-healing promoting effect of PUS, which is attributed to the distribution of modifiers, changes in chemical structure, and decomposition of macromolecules in asphalt after aging. The mobility of molecular chains and the number of hydrogen bonds in polymer modifiers containing dynamic disulfide bonds are important factors in the self-healing capacities.