Molecular Dynamics Simulation of Asphaltic Material

Abstract

An attempt is made to understand the chemical composition, oxidation mechanisms, and property changes of asphalt binders before and after oxidative aging using molecular dynamics (MD) simulations. Unoxidized and oxidized asphalts are subjected to different compressive and tensile stress rates, and moisture contents at room temperature. Results show that density, energy, and viscosity of the oxidized asphalt are higher than the unoxidized asphalt, indicating hardening and rheological property changes of asphalt after oxidation. Both the unoxidized and oxidized asphalts deform more and fail faster with an increase in stress rates, especially under tensile stress. The oxidized asphalt is stronger than the unoxidized asphalt under mechanical stress. Moisture inclusion affects viscosity more by decreasing the viscosity of the oxidized asphalt faster compared to the unoxidized asphalt. The viscosity of the oxidized asphalt is lower than that of the unoxidized asphalt above 5% moisture inclusion. This indicates that oxidized asphalt pavement might be exposed to more moisture-induced damage.