基于分子动力学模拟的橡胶改性沥青在集料表面的扩散特征研究

橡胶改性沥青和集料之间的界面作用与沥青路面的耐久性、高温稳定性有着重要联系而现有研究对该界面作用的微观认知尚不够全面。基于分子动力学模拟,以Materials Studio软件为研究工具,构建由基质沥青、天然橡胶沥青、顺丁橡胶沥青、丁苯橡胶沥青（15%掺量）与集料的4种主要矿物组成（石英、方解石、钠长石、微斜长石）两两构成的界面模型,从分子尺度上探究不同沥青组分在4种矿物表面的扩散行为,分析得到不同橡胶类型对其扩散作用的影响规律。结果表明：轻质组分在各矿物表面的扩散作用强于重质组分,相对分子质量对沥青组分的扩散速率起到关键作用;在不同矿物表面,橡胶分子链的加入对于提升沥青各组分扩散系数多为积极作用,且不同类型橡胶作用规律有所不同。研究结果可为不同矿料类型制备适配的橡胶改性沥青提供参考依据。

Study on Diffusion Characteristics of Rubber-modified Asphalt on Aggregate Surface Based on Molecular Dynamics Simulation

The interfacial interaction between rubber-modified asphalt and aggregate has an important connection with the durability and high-temperature stability of asphalt pavements. The microscopic knowledge of this interfacial interaction is not comprehensive in the existing studies. Based on the molecular dynamics simulation, taking Materials Studio software as the research tool, an interfacial model consisting of matrix asphalt, natural rubber asphalt, butadiene rubber asphalt, styrene butadiene rubber asphalt (15% admixture) and four mineral components (quartz, calcite, sodium feldspar, microplagioclase feldspar) in a two-by-two composition is built to explore the diffusion behavior of different asphalt components on the surface of the four aggregates from the molecular scale and to analyze the influence law of different rubber types on the diffusion effects. The results show that the diffusion of light components on the aggregate surface is stronger than that of heavy components, and the molecular weight plays a key role in the diffusion rate of asphalt components. On the surface of different aggregates, the addition of rubber molecular chains has a positive effect on enhancing the diffusion coefficient of asphalt components, and the action pattern of different types of rubber is different. The research result can provide a reference basis for the preparation of suitable rubber-modified asphalt for different mineral types.