Analysis of Regional Differences in Asphalt Binder Under All-Weather Aging Based on Rheological and Chemical Properties

Asphalt binder aging under natural exposure critically determines pavement durability, though current research inadequately captured performance evolution across diverse regional climates. This study investigated climate-driven degradation mechanisms through 12-month all-weather aging (AWA) tests in Gansu, Shandong, and Beijing via rheological (<i>G-R</i> parameter, stiffness modulus <i>S</i>-value) and chemical analyses (carbonyl index <i>I</i>_C=O, sulfoxide index <i>I</i>_S=O). The results demonstrated significant region-dependent aging disparities beyond laboratory simulation. In Gansu, extreme thermal fluctuations and UV radiation accelerated hardening via thermal stress cycles and photo-oxidation, yielding 52.4% higher <i>G-R</i> parameter than PAV. In Shandong, humid saline environments triggered sulfur oxidation-driven electrochemical corrosion, increasing <i>I</i>_S=O by 4.2% compared to PAV. In Beijing, synergistic UV-thermal oxidation elevated <i>I</i>_C=O and <i>S</i>-value by 8% and 40.7%, respectively versus PAV. Critically, <i>I</i>_C=O exhibited strong positive correlations with rheological degradation across regions (r > 0.90, <i>p</i> < 0.01). Based on <i>I</i>_C=O, the 12-month all-weather aging rate in Beijing exceeded Gansu and Shandong by 18.5% and 68%, revealing UV-thermal coupling as the most severe degradation pattern. Novelty lies in quantifying region-specific multi-factor coupling effects (UV-thermal, hygrothermal-salt, etc.) and demonstrating their superior severity over PAV (Beijing > Gansu > Shandong). Dominant environmental factors showed distinct regional variations: UV radiation and temperature difference dominated in Gansu (<i>I</i>_C=O, r = 0.76) and Beijing (0.74), while precipitation-<i>I</i>_C=O correlation prevailed in Shandong (0.76), yet multi-factor coupling ultimately governed aging. These findings provide theoretical foundations for region-tailored and climate-resilient asphalt pavement design.