基于分子动力学模拟的再生剂-老化沥青扩散机理

Diffusion Mechanism of Regenerant Aged Asphalt Based on Molecular Dynamics Simulation

采用Materials Studio(MS)分子动力学模拟软件对再生剂-老化沥青扩散体系进行研究.以沥青四组分试验为基础,选取12种分子模型构建再生剂分子组、复合水老化沥青分子组和复合紫外老化沥青分子组.针对在不同模拟时间、模拟温度和沥青成分条件下的老化沥青扩散体系进行模拟,得到扩散体系的扩散系数.结果表明:随着模拟时间的延长,再生剂在老化沥青扩散体系中的扩散系数变小,同时在复合紫外老化沥青扩散体系中的扩散系数小于复合水老化沥青扩散体系;随着扩散温度的增加,扩散系数增速逐渐变缓;再生剂中油性成分(芳香分和饱和分)的扩散系数大于极性成分(胶质和沥青质),芳香分由于多为链状且相对分子质量较小,其扩散速率在4种组分中最快.

The diffusion system of recycled asphalt was studied by using materials studio(MS)molecular dynamics simulation software.Based on the four component test of asphalt,12 molecular models were selected to construct the molecular groups of regenerator,the composite water aged asphalt and the composite UV aging asphalt.The diffusion coefficient of the diffusion system was obtained by simulating the aging asphalt diffusion system under different simulation time,simulated temperature and asphalt composition.The results show that the diffusion coefficient of the regenerator in the aging asphalt diffusion system decreases with the increase of the simulation time,and the diffusion coefficient of the composite UV aging asphalt diffusion system is smaller than that of the composite water aging asphalt diffusion system;with the increase of diffusion temperature,the growth rate of diffusion coefficient gradually slows;the diffusion coefficient of aromatic and saturated components of oil component in the regenerant is larger than that of polar component gum and asphaltene.Because the aromatic components are mostly chain and the relative molecular weight is small,the diffusion rate of the oil component is the fastest among the four components.