Influence of Waste Polyethylene on the Performances of Asphalt before and after Oxidative Aging Based on the Molecular Dynamics Simulation

Waste polyethylene (WPE) is a common waste that easily pollutes the environment. WPE has been used as a modifier to improve the high-temperature stability of asphalt. However, the performance change of WPE modified asphalt during oxidative aging is still unknown. The purpose of this article is to study the effect of WPE on the performance of asphalt before and after oxidative aging by using the molecular dynamics method. First, the density, viscosity, glass transition temperature, and cohesive energy density (CED) of WPE modified asphalt before and after oxidative aging were calculated. WPE reduces the viscosity change of asphalt during oxidative aging. WPE reduces the CED value of asphalt, thereby weakening the force between asphalt molecules. In addition, the glass transition temperature indicates that WPE can alleviate the effect of oxidative aging on the reduction of the viscoelastic properties of asphalt. The viscoelasticity of 4wt% WPE modified asphalt remains almost unchanged before and after oxidative aging. In addition, WPE molecules can improve the self-healing ability of asphalt during oxidative aging.