摘要
为了从纳观层面分析沥青的自愈合行为,通过分子动力学(MD)方法构建沥青分子模型,模拟裂缝两侧材料间的扩散融合过程分析沥青的自愈合行为和扩散融合效率,并提出纳观尺度上描述沥青自愈合能力的表征方法和参数。研究结果表明,沥青材料的自愈合行为在纳观上主要分为2个阶段:运动至完全接触阶段和扩散阶段。运动至完全接触阶段是体积发生变化的主要阶段,当达到完全接触状态时,扩散融合后沥青材料自愈合模型的体积会达到一个稳定值。模拟结果表明,分子扩散在自愈合过程中起着重要作用,扩散能力和效率的增大能提高沥青的自愈合性能。自愈合过程中模型的体积和密度均会随着温度的变化而变化,随着温度的升高,材料自愈合效率提高。同时,在扩散融合过程达到稳定后,自愈合模型的密度与单个沥青模型在同温度下的密度十分近似,表明在这一温度条件下沥青材料的自愈合过程基本完成。由此表明采用模型的相对浓度、内聚能密度CED和自由体积分数FFV能够有效表征沥青材料的自愈合程度和效率。
In order to reveal the self-healing mechanism of asphalt at the nano scale, a model of the molecular structure of asphalt was constructed using the molecular dynamics(MD) method in the study. The diffusion process between different asphalt layer materials was analyzed to characterize the self-healing behavior and diffusion efficiency of asphalt, and the characterization parameters describing the self-healing ability of asphalt materials at the nanoscale were proposed. The results show that the self-healing behavior of asphalt materials at the nanoscale can be divided into two stages: the movement to complete contact stage and the diffusion and fusion stage. The movement to the complete contact stage is the main stage in which the volume changes. When the complete contact state is reached, the volume of the self-healing model would reach a stable value after diffusion and fusion. The results show that molecular diffusion plays an important role in the self-healing process,and the increase of diffusion capacity and efficiency improves the self-healing performance of asphalt. During the self-healing process, the volume and density of the model change with the temperature. As the temperature increases, the self-healing efficiency of the asphalt material increases. At the same time, after the diffusion and fusion process is stabilized, the density of the self-healing model is very similar to the density of a single asphalt layer at the same temperature, indicating that the self-healing process of the asphalt material is basically completed at this temperature. This indicates that the relative concentration, cohesive energy density CED, and free volume fraction FFV of the model can effectively characterize the self-healing ability and efficiency of asphalt materials.
作者
詹易群
吴昊
宋卫民
朱琳
ZHAN Yiqun;WU Hao;SONG Weimin;ZHU Lin(School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2023年第2期611-619,共9页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(52008405,51778638)
湖南省自然科学基金资助项目(2020JJ5744)。
关键词
自愈合
分子动力学
扩散行为
相对浓度
内聚能密度
self-healing
molecular dynamics
diffusion coefficient
relative concentration
cohesive energy density
