Microstructure, Fatigue, and Self-Healing Properties of SBS-Modified Asphalt under Ultraviolet Radiation

Asphalt gradually deteriorates under the influence of ultraviolet light, especially at high altitudes or low latitudes, significantly shortening the service life of pavements. In this study, styrene-butadiene-styrene copolymer–modified asphalt was selected to investigate the effects of ultraviolet aging on the basic indexes and micromorphology of asphalt, as well as on the fatigue performance and self-healing ability of asphalt mixtures. The experimental results indicate that ultraviolet radiation exposure increased the content of polar molecules in the asphalt, which gradually aggregated, and the surface roughness of the asphalt increased. With the prolongation of irradiation time, the average value and dispersion degree of Young's modulus associated with the asphalt surface gradually increased. Moisture accelerated the aging of asphalt, increasing penetration and surface roughness; however, it prevented the aggregation of polar molecules. Ultraviolet light weakened the fatigue properties of asphalt mixtures, and the self-healing effect after fatigue gradually deteriorated. The self-healing effect of the asphalt mixture was inversely proportional to the degree of aging and damage, and was proportional to the healing temperature and healing time.