微观尺度下生物再生剂−沥青的融合扩散特性

Study on fusion diffusion characteristics of bio-based rejuvenator-asphalt at micro scale

运用分子动力学方法构建生物再生剂−沥青模型,通过微观模拟探究再生剂−沥青的融合扩散行为.首先采用FTIR试验结合SARA模型确定老化前后的12种沥青分子结构,选用动物废弃物生物再生剂的主要成分类固醇和羧酸,建立沥青−再生剂的扩散体系分子动力学模型.采用密度、相容性指标验证分子动力学模型的可靠性,分析不同温度、老化状态下生物再生剂在基质沥青与老化沥青中的融合扩散行为.结果表明:生物再生剂在老化沥青中的扩散系数高于在基质沥青中的扩散系数;在相同温度下类固醇的扩散性能优于羧酸;两种生物再生剂的扩散系数随着温度升高而升高,高温条件下体系动能更大,使体系分子更容易摆脱分子力的约束.

The molecular dynamics method was used to construct the bio-based rejuvenator-asphalt model,and the fusion diffusion behavior of bio-based rejuvenator-asphalt was investigated by microscopic simulation.Firstly,the FTIR test combined with the SARA model was used to determine the molecular structure of 12 kinds of asphalt before and after aging.And the main components of animal waste bio-based rejuvenators including steroids and carboxylic acids were selected to establish the molecular dynamics model of the asphaltrejuvenator diffusion system.Furthermore,the density and compatibility index were used to verify the reliability of the molecular dynamics model,and the fusion diffusion behavior of bio-based rejuvenator in virgin asphalt and aged asphalt were analyzed under different temperatures and aging conditions.The results show that the diffusion coefficients of bio-based rejuvenator in aged asphalt is higher than that in virgin asphalt.The diffusion performance of steroids is better than carboxylic acids at the same temperature.The diffusion coefficients of two bio-based rejuvenators increase with the increase of temperature,since the greater kinetic energy at high temperature makes it easier for the system molecules to get rid of the constraint of molecular force.