Oxygen Diffusion Behavior in Asphalt Film Based on Molecular Dynamics Simulation
Asphalt aging is one of the most important concerns during the use of asphalt pavement.However,asphalt usually exists in the form of a film in the mixture.Oxygen diffusion is an important factor affecting asphalt aging.To investigate the oxygen diffusion behavior in asphalt film under different working conditions,an oxygen-asphalt-aggregate(OAA)model was developed in this study to simulate the state of the asphalt film on the aggregate surface under real conditions.Oxygen diffusion and asphalt component migration in the OAA model were investigated under different conditions of time,temperature,oxygen concentration,and aggregate type.The influence of each factor on the molecular behavior of the model was compared by calculating the relative concentration of molecules,radial distribution function,mean square displacement,and diffusion coefficient,and the connection between the parameters was further analyzed.From the molecular simulation results,it is clear that the oxygen concentration increases with the increase in diffusion time,and the oxygen concentration at the interface between aggregate and asphalt increases significantly.Higher temperature promotes the diffusion of oxygen into the asphalt film,and oxygen concentration varies nearly linearly with temperature.Increasing the number of oxygen molecules can make the relative concentration of oxygen molecules within the asphalt film increase overall,and the CaCO3 aggregate is more favorable for oxygen diffusion into the asphalt film.
NETL
NSTL
万方数据
