Low-temperature flexural tensile performance degradation of asphalt mixture under coupled UV radiation and freeze-thaw cycles

The Qinghai-Tibetan Plateau in China experiences extreme climatic conditions, including intense ultraviolet (UV) radiation, frequent freeze-thaw cycles (FTCs). This study aims to investigate the degradation of low-temperature flexural tensile performance in asphalt mixtures subjected to UV radiation, FTCs, their coupled effects. An alternating two-factor laboratory procedure was designed to simulate these conditions, and three-point bending beam tests were conducted on asphalt mixture beams after exposure to various durations of UV radiation and FTCs. A comprehensive multi-indicator approach was employed to assess the performance degradation. The results revealed that UV radiation primarily reduced the low-temperature flexural tensile strain of asphalt mixtures, while FTCs mainly weakened the tensile strength. FTCs were the predominant factor in performance degradation. Their coupling effects resulted in a pronounced mutual enhancement of damage, with damage variables increment value under coupled conditions being more than seven times greater than those in the control group.