Effect of Iron Oxide on Self-Healing and Thermal Characteristics of Asphalt Based on Molecular Dynamics Simulation Perspective

To compare the effects of two powders, iron oxide and mineral, on the healing process of asphalt molecules, Fe2O3-asphalt and SiO2-asphalt were constructed by Material Studio software (MS). The mean square displacement, diffusion coefficient, concentration distribution of the asphalt layer, and the thermal conductivity of the two models were analyzed to evaluate the influence of two powders on the diffusion behavior of asphalt molecules on a microlevel. The results show that the effect of Fe2O3 on the diffusion rate of asphalt molecules is greater than that of SiO2 at high temperature, but the effects are similar at low temperature. The diffusion coefficient of the Fe2O3-asphalt model increases faster than that of the SiO2-asphalt model with increasing temperature. Compared with SiO2, Fe2O3 is more conducive to the model’s reaching a state of uniform concentration, which is manifested as the rapid repair of cracks on a macrolevel. The thermal conductivity of the Fe2O3-asphalt model is higher than that of the SiO2-asphalt model.