沥青混合料界面黏附黏结效应分子动力学研究

Study on Molecular Dynamics of Interfacial Adhesion and Cohesion of Asphalt Mixture

采用四组分法建立沥青模型,通过密度比照,径向分布函数分析,内聚能密度和溶解度参数测算,验证沥青模型合理性。建立沥青-SiO_(2)晶体界面模型及沥青-沥青界面模型,通过不同温度下的动力学模拟,分析沥青混合料界面能。对微观状态下的沥青混合料界面能随温度升高的变化规律进行研究。结果表明:在升温过程中,沥青能量的变化是界面能量变化的主要影响因素;在相同温度下,沥青-SiO_(2)两相界面的黏附强度比沥青-沥青界面的黏结强度高,且两种界面能的变化规律相似。通过沥青胶体结构以及四组分随温度升高扩散系数变化的分析发现:温度升高对不同组分扩散速率的影响使得沥青胶体稳定性发生了改变,而分子动能增加使得分子间作用力的减小,是高温状态下黏附能和黏结能降低的影响因素之一。

The four-component method has been used to establish the asphalt model,and the rationalization of the asphalt model has been verified by density comparison,radial distribution function analysis,cohesion energy density and solubility parameter calculation.The asphalt-SiO_(2) crystal interface model and the asphalt-asphalt interface model have been established to analyze the interface energy of asphalt mixture through dynamic simulation at different temperatures.The change law of the interface energy of asphalt mixture with the increase of temperature has been studied under micro state.The result shows that the change of asphalt energy is the principal influencing factor of the interface energy change during heating process.And the bonding strength of asphalt-SiO_(2) two-phase interface is higher than that of asphalt-asphalt interface at the same temperature and the change rules of the two interface energies are similar.Through the analysis of the change of diffusion coefficient of asphalt colloid structure and four components along with temperature rising,it is found that the stability of asphalt colloid has changed due to the influence of temperature increase on the diffusion rate of different components and the decrease of intermolecular force due to the increase of molecular motion energy is one of the influencing factors for the decrease of adhesion energy and cohesion energy at high temperature.