Multi-scale evaluation of asphalt-aggregate adhesion and failure behaviour under oxidative aging and moisture coupling
Guojing Huang, Zixuan Chen, Shuai Wang, Xibo Wang, Wenxin Huang, Jianzhong Pei, Jiupeng Zhang
Abstract
The durability of asphalt pavements is significantly affected by the deterioration of asphalt-aggregate adhesion caused by oxidative aging and moisture exposure. This study investigates their individual and synergistic effects through a multi-scale approach combining molecular dynamics (MD) simulations and laboratory experiments. The results show that oxidative aging enhances asphalt cohesion and asphalt-aggregate adhesion. However, water infiltration reduces the high concentration distribution of asphalt on the aggregate surface and disperses asphalt distribution, thereby weakening interfacial adhesion. The incorporation of activated crumb rubber improves both interfacial bond strength and the raveling resistance of the mixture, with alkaline aggregates (high in CaO content) exhibiting superior adhesion to the asphalt compared to acidic aggregates (high in SiO2 content). Oxidative aging improves asphalt-aggregate adhesion in dry conditions, while moisture adversely affects interfacial adhesion, and the coupling of moisture and aging exacerbates the degradation of interfacial adhesion. Statistical analysis confirmed that the interaction between aging and moisture has a significant detrimental effect on interfacial adhesion. These insights advance the understanding of the degradation mechanisms of asphalt-aggregate adhesion under oxidative aging and moisture conditions and provide valuable guidance for the design of highly durable asphalt mixtures.