Xu Haoping, Xu Wenyuan, Zheng Xuewen, Cao Kai
School of Civil Engineering, Northeast Forestry University, Harbin 150040, China.
College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China.
Polymers (Basel). 2022 Aug 30;14(17):3581. doi: 10.3390/polym14173581.
In order to study the characteristics and laws of nanocrack generation and self-healing behavior of asphalt materials under tensile action, the molecular dynamics (MD) method was used to simulate the continuous "tensile failure-self-healing" process, and this study remedies the shortcomings of existing experimental and observational methods. It is found that the MD-reproduced formation process of asphalt binder nanocrack contains four stages: "tensile extension", "nanocrack generation", "crack adding, expanding and penetrating" and "cracking failure". The influence of tensile conditions on the tensile cracking simulation of an asphalt binder model was analyzed, and it was found that low temperature and high loading rate would increase the tensile strength of the asphalt binder model. In addition, the MD-reproduced healing process of asphalt binder nanocracks can be divided into four stages: "surface approach", "surface rearrangement", "surface wetting" and "diffusion", which is similar to the healing process of polymers. Finally, from the perspective of energy change, the change rule of dominant van der Waals energy in the self-healing process was studied. Based on the existing research, the influence of damage degree on the healing performance of asphalt binder and its mechanism were further analyzed. The research results further enrich the theoretical research on microlevel cracking and healing of asphalt materials, and have certain theoretical value for the further development of self-healing asphalt materials.
为研究沥青材料在拉伸作用下纳米裂纹产生及自愈合行为的特征和规律，采用分子动力学（MD）方法模拟连续的“拉伸破坏-自愈合”过程，该研究弥补了现有实验和观测方法的不足。研究发现，MD模拟的沥青结合料纳米裂纹形成过程包含“拉伸扩展”“纳米裂纹产生”“裂纹增加、扩展及贯穿”和“开裂破坏”四个阶段。分析了拉伸条件对沥青结合料模型拉伸开裂模拟的影响，发现低温和高加载速率会提高沥青结合料模型的拉伸强度。此外，MD模拟的沥青结合料纳米裂纹愈合过程可分为“表面靠近”“表面重排”“表面润湿”和“扩散”四个阶段，这与聚合物的愈合过程相似。最后，从能量变化的角度，研究了自愈合过程中主导范德华能的变化规律。基于现有研究，进一步分析了损伤程度对沥青结合料愈合性能的影响及其机理。研究结果进一步丰富了沥青材料微观开裂与愈合的理论研究，对自愈合沥青材料的进一步发展具有一定的理论价值。
