Interfacial adhesion properties and debonding mechanisms in rejuvenated asphalt mixtures

The interfacial strength between asphalt and aggregate significantly affects the macroscopic properties of rejuvenated asphalt mixtures. Investigating the interfacial properties of rejuvenated asphalt mixtures contributes to understanding the adhesion mechanisms and debonding behavior, enhancing the service life of rejuvenated asphalt mixtures. In this study, molecular dynamics methods were utilized to construct interface models of virgin, aged, and rejuvenated asphalt-aggregate systems, subsequent to which asphalt-aggregate interface pull-out tests were conducted. The findings revealed that the exponential-type cohesive zone model (CZM) effectively characterize the stress-strain correlations during asphalt-aggregate interface pull-out tests. The combination of adhesive and cohesive failure is the typical damage modes at asphalt-aggregate interface. Cohesive failure tended to be the main failure mode between aged asphalt-aggregate interface, while asphalt oxidation aging notably reduced the interface tensile strength and hence the cracking resistance of asphalt mixtures. The interface failure patterns between rejuvenated and virgin asphalt were similar, demonstrating an adhesive failure at lower temperatures and a shift towards cohesion failure at higher temperatures. The interface failure usually occurred at lower temperatures especially for aged asphalt, while the incorporation of rejuvenator could effectively mitigate the cracking potential asphalt mixtures. This study simulated the interfacial failure behavior for rejuvenated asphalt mixtures, which can be a theoretical basis of using rejuvenator in recycled asphalt mixtures.