Thermal-ultraviolet-humidness Coupling Aging Mechanisms of SBS Modified Asphalt Considering Actual Climatic Conditions

Styrene-butadiene-styrene (SBS) modified asphalt is susceptible to aging due to the combined effects of environmental factors, including temperature, ultraviolet radiation, and humidness. However, existing studies primarily focus on single aging conditions, neglecting the synergistic effects of thermal, ultraviolet, and humidness factors on the aging properties of asphalt. Given the vast territory and significant environmental variations in China, this study selects five representative cities as subjects for research. The research utilizes the Rolling Thin Film Oven Test (RTFOT) in combination with a coupled aging chamber to simulate the aging process. This study analyzes the effects of varying temperature, duration of ultraviolet radiation exposure, and humidness conditions on the macroscopic performance of asphalt, specifically through ductility and softening point tests. Additionally, it elucidates the aging mechanisms of SBS modified asphalt using Fourier Transform Infrared Spectroscopy (FTIR) and fluorescence microscopy (FM). The results indicate that high humidness and temperature environments significantly accelerate the aging of asphalt, with temperature playing a dominant role in hastening the aging process of SBS-modified asphalt. Microscopic analysis reveals that the primary mechanisms of SBS degradation and oxidation reactions occur during the aging process. Notably, the change in the functional group index of SBS-modified asphalt under high humidness and temperature conditions is most pronounced. The decomposition of the SBS network crosslinking structure is most severe, resulting in the weakest fluorescence intensity.