Molecular dynamics study of interfacial mechanical behavior between asphalt binder and mineral aggregate

This study aims to study the deformation and failure behavior of the asphalt-aggregate interface using molecular dynamics (MD) simulations. The 12-component asphalt molecular models and the hydrated silica substrate were employed to form a bi-material interface system. Physical properties of asphalt binder were predicted from MD simulations including density and glass transition temperature for model validation with experimental data. Tensile simulations were performed and the stress-separation responses were obtained to analyze the interfacial mechanical behavior. It was found that the interface failure was mainly adhesive failure although large air voids were formed in the bulk asphalt as the loading rate decreases to a certain level. The interface failure strength and post-peak deformation are affected by loading rate and temperature that is consistent the viscoelastic behavior of asphalt binder. The stress-separation responses match the cohesive zone model (CZM) model that is usually observed in the pull-off strength test at the macroscopic scale. The relationship between chemical compositions of asphalt binder and the interface failure parameters was investigated. The MD simulation shows promising results to understand mechanical failure of asphalt-aggregate interface at the atomistic scale.