Study on the Effect of Natural Aging and PAV Aging on Asphalt Binder Based on Rheology and Microstructural Composition

Laboratory-simulated aging fails to fully replicate the complex aging behavior of asphalt binder under actual environmental conditions. This study aims to analyze the differences between natural aging and PAV aging of asphalt binder. In order to achieve the goal, in-door and natural environments were used to age the asphalt binder. The divergence in asphalt binder aging behavior was systematically investigated through encompassing low-temperature performance, chemical structure, elemental composition, molecular weight, and macroscopic and microscopic performance correlation analyses. Key findings include: The harsh environmental conditions in cold-arid region resulted in inferior low-temperature performance of naturally aged asphalt binder (12 months) compared to PAV-aged counterparts. Natural aging induced more significant asphalt binder’s chemi-cal structural changes than PAV aging, but exhibited less prominent oxidative reactions and macromolecular structure formation. Whether macroscopic or microscopic perfor-mance, hot oxygen was the main reason for the natural aging behavior of asphalt binder. The influence of other factors on the aging behavior of asphalt binder was not significant. The forced aging of PAV aging affected the cross-scale behaviors between oxygen content, molecular weight, and low-temperature performance in asphalt binder. This diminished the influence of oxygen content and molecular weight on the degradation of low-temperature performance, resulting in discrepancies compared to natural aging.