沥青自愈合阶段组分扩散的分子动力学研究

为了研究沥青在自愈合时各组分的扩散行为,采用分子模拟的方法,利用沥青四组分分析法建立沥青分子模型,并用沥青分子建立裂缝模型。模拟了不同温度、压强和老化条件下沥青四组分在愈合时的扩散过程,得到愈合模型的密度和均方位移曲线,并模拟计算了各组分的扩散系数。结果表明:沥青裂缝模型愈合分为3个过程,分别是密度恢复阶段、结构恢复阶段和愈合后分子自扩散阶段;沥青在愈合过程中的扩散系数从大到小排列分别为:饱和分、芳香分、沥青质、胶质;在沥青愈合时,升温升压能够促进沥青分子运动;相同条件下,老化沥青愈合时的扩散系数明显小于未老化沥青的扩散系数;在沥青四组分当中,胶质在愈合时的扩散系数受环境变化影响最小。

Molecular Dynamics Simulation on Fraction Diffusion in Asphalt Self-Healing

In order to study the self-healing process of asphalt, in molecular dynamics, the model of asphalt and the crack model were established by four-fraction analysis method. The diffusion process of the four fractions in the healing process was simulated with different temperature, pressure and aging content. The density and mean square displacement curves of the healing model were obtained and the diffusion coefficients of the healing stage were calculated. The results show that the self -healing process of asphalt can be divided into three stages of density recovery stage, structure recovery stage and self-diffusion stage; the diffusion coefficients of asphalt in the process of healing are ranked in the order: saturates>aromatics>asphaltenes>resins; in asphalt healing, temperature and pressure increase can promote the movement of asphalt molecules; in the same condition, the diffusion coefficient of aged asphalt healing is obviously lower than that of unaged asphalt. Among the four fractions of asphalt, the diffusion of resin during healing is least affected by environmental changes.