Molecular dynamics simulation on the rejuvenation effects of waste cooking oil on aged asphalt binder

Waste cooking oil (WCO) has received attention on rejuvenating aged asphalt binder widely in recent years. This study evaluated the rejuvenation effects of WCO on aged asphalt binder on the micro-scale using molecular dynamics (MD) simulation. First, the representative molecules of WCO and asphalt binders were selected. The molecular mixture model was then developed. The thermodynamic properties were investigated, including density, cohesive energy density, solubility parameter, and surface free energy. The results show that WCO can restore the thermodynamic properties of aged asphalt binder to some extent and WCO has different influences on electrostatic interactions and van der Waals effects. From the diffusion behavior and molecular structure of asphalt binder, WCO can improve the molecular mobility and restore the colloidal structure. Besides, the adhesion work and moisture susceptibility of asphalt binder-aggregate interfaces (calcite and quartz) were evaluated. The results show that WCO can improve adhesion work between asphalt binder and aggregates since WCO can change molecular structure of asphalt binders and certain adhesion work exists between WCO and aggregates. Also, it can mitigate the moisture susceptibility of asphalt binder-aggregate interfaces (calcite and quartz). The study demonstrates that the MD simulation can help to understand the rejuvenation effects of WCO on aged asphalt binder on the micro-scale.