Weathering aging resistance in seasonal frozen regions: A comparative study of SBS- and SBR-modified asphalt binders through rheological and morphological characterization

In seasonal frozen regions, asphalt pavements face accelerated degradation due to extreme environmental stressors-including cyclic freeze-thaw transitions and intense ultraviolet radiation-that induce severe thermo-oxidative and UV aging effects. These compounded aging mechanisms lead to premature cracking, raveling, and functional failure of road surfaces, imposing significant economic burdens on infrastructure maintenance. To address this critical challenge, this study systematically investigates the alterations in the rheological properties of AH-90 base asphalt, SBR-modified asphalt, and SBS-modified asphalt under natural aging conditions over varying time intervals using temperature sweep tests, bending beam rheometer tests, and multi-stress creep recovery tests. The influence of natural weather conditions on the microstructure of asphalt binders was examined by Fourier transform infrared spectroscopy and fluorescence microscopy before and after different nature aging conditions. The findings demonstrate that the use of modifiers can modify the natural aging characteristics of asphalt binders. Compared to BA, SBS demonstrates superior resilience to natural aging, while SBR is more susceptible to aging. After natural aging, the stiffness modulus of BA, SBS, and SBR increased by 21%, 10%, and 39% respectively. T30 (The temperature at which the limiting phase angles grades reaches 30°) exhibits a robust association with the intrinsic aging features of asphalt binders, facilitating the assessment of natural aging impacts on asphalt qualities. Throughout natural aging, the modifier deteriorates due to the oxidation of the unsaturated polybutadiene component by chain scission, while SBS exhibits a more stable phase structure than SBR during the aging process.