Study on the anti-aging performance of O-Pal/SBS composite modified asphalt under multifactor coupling conditions

High-performance composite asphalt is widely used in drainage asphalt pavements in rainy environments; however, in long-term service, complex environmental conditions have different degrees of impact on road performance. Therefore, in this study, a coupled aging test with immersion-ultraviolet irradiation cycles was designed to investigate the effects of thermal oxygen, ultraviolet irradiation and immersion conditions on the long-term aging process of O-Pal/SBS composite asphalt. The rheological properties, microstructure, modification mechanism and water stability of the composite-modified asphalt before and after aging were evaluated by DSR, FM, FTIR and SFE experiments, respectively. The results show that UV irradiation accelerates the physicochemical reactions on the surface of the asphalt film with immersion in water, acid rain and salt solution, which results in the rapid occurrence of different degrees of damage, such as roughening and cracking. Moreover, coupled aging treatments also have different degrees of negative effects on the high- and low-temperature performance, viscoelastic ratios and antifatigue properties of the asphalt during long-term aging. At the microstructural level, O-Pal at a content of 3 wt% can produce a stable crosslinked chain structure, addressing the problem in which asphalt molecular chains break and oxidize due to ultraviolet rays during long-term aging. The conclusions of this study provide new ideas for subsequent research on the aging resistance and water damage resistance of composite-modified asphalt in complex environments.