氧化石墨烯改性沥青与表面各向异性集料界面相互作用研究

Study on Interface Interaction Between Graphene Oxide Modified Asphalt and Surface Anisotropic Aggregate

在原子尺度上探究了干燥与水分入侵环境下氧化石墨烯(GO)改性沥青与表面各向异性集料界面黏附性能.采用分子动力学模拟方法研究了GO改性12组分沥青分别与典型弱碱性集料方解石和酸性集料α-石英的各向异性晶面的分子相互作用.在验证模型密度、热力学参数合理的基础上,以径向分布函数和相对浓度表征了沥青组分与GO在集料表面的分布和浓度情况.另外,计算体系黏附能分析了不同条件下GO改性沥青-集料界面黏附性能的差异.结果表明,GO分子由于其较大的比表面积和表面修饰活性位置,相比沥青其他组分大量聚集在沥青-集料界面之间,结合矿物不同表面原子密度和离子活性,无论是集料处于干燥状态或被水分入侵时,GO改性均显著提高了沥青与集料之间的黏附性能.由于Si原子在GO分子表面的高负载量,使得GO改性沥青与石英(一种酸性集料)比方解石(一种碱性集料)有更强的黏结强度.

In this study,the interfacial adhesion properties of graphene oxide(GO) modified asphalt to surface anisotropic aggregates were investigated at atomic scale in dry and water intrusion environments. Molecular dynamics simulation was used to study the molecular interaction between GO modified 12 component asphalt and the anisotropic crystal planes of typical weak alkali aggregate,calcite,and acid aggregate,α-quartz,respectively. On the basis of verifying that the density and thermodynamic parameters of the model are reasonable,the distribution and concentration of asphalt components and GO on the aggregate surface are characterized by Radial Distribution Function and Relative concentration Profile. In addition,the adhesion energy was used to calculate the difference of the adhesion performance of GO modified asphalt aggregate interface under different conditions. The results show that GO molecules,due to their large specific surface area and active sites of surface modification,are more concentrated in the interface between asphalt and aggregate than other components of asphalt.Combined with different surface atomic density and ionic activity of minerals,GO modified asphalt can significantly improve the adhesion between asphalt and aggregate in both dry and water intrusion environments.Due to the high loading of Si atoms on the surface of GO molecules,GO modified asphalt has stronger bond strength with quartz(an acidic aggregate)such as calcite(an alkaline aggregate).