Debonding of asphalt-aggregate interface under coupled moisture and temperature conditions: An atomistic study

Moisture and temperature are the primary factors contributing to the premature degradation of asphalt pavement. This study systematically investigated the debonding behaviors at the asphalt-aggregate interface under coupled moisture and temperature conditions using molecular dynamics simulations. The cohesive and adhesive behaviors of asphalt-water-aggregate systems were assessed through tensile testing, and the interaction details among asphalt, water, and aggregate were characterized. Results indicated that moisture and temperature synergistically promoted the debonding of the asphalt-aggregate interface. Water layers significantly weakened the interfacial bonding between asphalt and aggregate, primarily due to the accelerated formation of voids and diffusion behaviors at the interface. Temperature notably affected the cohesive and adhesive performance of asphalt-aggregate interfaces, with failure modes shifting from adhesive to cohesive as temperature increased. The reduction in cohesive capability was mainly attributed to weakened interactions between polar and nonpolar components, as well as interactions within the nonpolar components at elevated temperatures. A deeper understanding of the debonding behaviors at the asphalt-aggregate interface can provide valuable insights into failure mechanisms, aiding in the design of durable asphalt pavement through nano-engineering.