Study of the Mixing between Asphalt and Rejuvenator in Hot In-Place Recycled Layer
Yajing Zhu, Tao Ma, Guangji Xu, Jianwei Fan, Yiming Zhang, Meng Wu
Abstract
Ideal mixing between the asphalt and rejuvenator is the key to ensure the performance of the recycled asphalt mixture in hot in-place recycling. In this paper, the undetermined temperature and thermal parameters in the finite-element (FE) model of pavement were back calculated by the backward method of regression. The temperature field of the recycled asphalt layer after paving was obtained by FE simulation, and was applied to set the temperature in the subsequent molecular dynamics (MD) simulation. Molecular models of virgin asphalt, aged asphalt, and the representative rejuvenator components were applied to establish a three-layer model. New indicators were defined to analyze the interdiffusion between the virgin asphalt, aged asphalt, and rejuvenator, and the microstructure, interdiffusion, and interaction states between the asphalt and rejuvenator in the asphalt miscibility zone were analyzed. Results show that the parameter transferring from the macro FE simulated temperature field to the micro temperature setting of MD model is feasible. There is an obvious difference between the temperature fields on the surface and the inside hot in-place recycled asphalt layer during the cooling process, which causes different interaction and interdiffusion states between the asphalt and rejuvenator as well as the uneven performance of the recycled asphalt mixture. The effects of chain and aromatic rejuvenator on different interdiffusion and interaction indicators are different, so the combination of the two could have a better rejuvenation effect. The results can offer reference in aspects including prescreening the recycling temperature, the proportion of rejuvenator, virgin asphalt and aged asphalt, the rejuvenator component composition, and other parameters in hot in-place recycling.