新-旧沥青界面再生流变特征及分子动力学模拟研究

Rheological Characteristics and Molecular Dynamics Simulation of Interface Regeneration Between Virgin and Aged Asphalts

为扩展研究新-旧沥青界面再生融合行为的方法,量化表征界面再生融合速率、融合程度等参数,通过构建新-旧双层沥青试样模型,分别基于动态剪切试验(DSR)测试试样界面的再生流变特征,基于分子动力学系统(MS)模拟试样界面的再生机制和过程,同时验证不同试验条件下试样界面再生流变特征测试结果。研究结果表明:随着新添沥青标号的增加,新-旧沥青界面再生融合程度显著增大,再生融合速率明显提高;随着加热时间的增加,新-旧沥青界面再生融合程度逐渐增大,但再生融合速率呈指数递减;随着加热温度的增加,高标号新添沥青的界面再生融合程度和界面再生融合速率均呈线性增大,而低标号新添沥青呈抛物线形增大;分子动力学系统模拟计算结果与动态剪切流变特征实测结果具有较好的关联性,表明选取的分子结构模型和计算参数合理,采用分子动力学技术模拟新-旧沥青界面再生融合行为的方法和思路是可行的。

To extend the research methods on interface regeneration characteristics and diffusion behaviors between virgin and aged asphalts, and to quantitatively describe parameters such as interface diffusion coefficient(D) and interface regeneration degree of blending(DOB) by building double layer specimens and models with virgin and aged asphalts, the rheological properties of specimens were measured using dynamic shear rheometry(DSR) tests. The interface regeneration mechanisms and processes of models were simulated using a molecular dynamics system(MS). Meanwhile, the rheological properties of specimens were verified by models under different test conditions. The results show that the DOB and D values of virgin-aged asphalt specimens both increase significantly with improvement in virgin asphalt grade. With prolonged heating time, the DOB values of virgin-aged asphalt specimens increase gradually, whereas the D values decrease exponentially. With the increase in heating temperature, the DOB and D values of virgin-aged asphalt specimens both increase linearly for higher grade virgin asphalt and parabolically for lower grade virgin asphalt. The simulation results of MS show excellent correlations with the measurement results from DSR, which indicates that the molecular structure models and calculation parameters that were selected are reasonable. Further, the molecular dynamics technique is a feasible method for simulating the interface regeneration characteristics and diffusion behaviors between virgin and aged asphalt binders.