Thermodynamic properties analysis of warm-mix recycled asphalt binders using molecular dynamics simulation

Abstract

This study aims at investigating the effect of warm-mix recycled on the thermodynamic properties of aged asphalt binders using molecular dynamics simulation. The molecular models of asphalt binders in the virgin, long-term aged, recycled and warm-mix recycled states were developed based on the proportional relationships between the asphalt components as well as oxidation functional indicators. The mean square displacement, molecular radial distribution function and fractional free volume were used to evaluate the molecular structure variations in different asphalt states. Based on this study, it is found that the composite regenerator cannot completely degrade the oxidation functional groups in the aged asphalt, but rather mainly rely on small molecular structures penetrating and filling the intermolecular aggregation spaces of the asphaltene to reduce asphalt brittleness and hardness. The warm mix recycling processes mainly depend on increasing the activity of the lighter components to improve the diffusion properties of the aged asphalt.