Study on the aging performance of SBS modified asphalt in humid and hot environment.

This study focused on the aging issues of asphalt pavement in high-temperature and high-humidity climatic zones, using SBS-modified asphalt with different additive contents as research objects to systematically investigate the aging evolution mechanisms under coupled hygrothermal conditions. A dual-temperature control system (60°C and 70°C) was constructed to conduct thermal-oxidative aging and wet-dry cycle aging tests. Multidimensional indicators including penetration ratio, softening point ratio, and ductility ratio were utilized to characterize the time-dependent aging characteristics of materials. Additionally, dynamic shear rheology (DSR) tests and rutting tests were integrated to comprehensively evaluate the high-temperature performance degradation of asphalt and its mixtures with varying modifier contents under cyclic aging. The research aimed to reveal the hygrothermal-coupled aging mechanisms and provide theoretical foundations for durable pavement design in humid tropical regions. Experimental results demonstrated that after thermal-oxidative and wet-dry cycle aging at 60°C and 70°C, the performance indices of SBS-modified asphalt with different additive contents deteriorated significantly. Specifically, the penetration ratio decreased by an average of 29.1%, the ductility ratio declined by 14.6%, and the softening point ratio increased by 60.3%. Concurrently, high-temperature rheological performance exhibited progressive degradation. Notably, increased SBS modifier content was observed to mitigate the aging-induced performance attenuation of modified asphalt. Analytical findings suggested that while higher SBS content enhanced structural stability to some extent, the presence of elevated temperature and moisture accelerated the degradation of SBS modifiers and the aging of base asphalt, thereby exacerbating the overall aging of modified asphalt and leading to performance deterioration.