Wang Xianfeng, Xie Wei, Li Taoran, Ren Jun, Zhu Jihua, Han Ningxu, Xing Feng
Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China.
School of Science, Harbin Institute of Technology, Shenzhen 518055, China.
Materials (Basel). 2020 Sep 12;13(18):4054. doi: 10.3390/ma13184054.
Microcapsule based self-healing concrete can automatically repair damage and improve the durability of concrete structures, the performance of which depends on the binding behavior between the microcapsule wall and cement matrix. However, conventional experimental methods could not provide detailed information on a microscopic level. In this paper, through molecular dynamics simulation, three composite models of Tobermorite (Tobermorite 9 Å, Tobermorite 11 Å, Tobermorite 14 Å), a mineral similar to Calcium-Silicate-Hydrate (C-S-H) gel, with the linear urea-formaldehyde (UF), the shell of the microcapsule, were established to investigate the mechanical properties and interface binding behaviour of the Tobermorite/UF composite. The results showed that the Young's modulus, shear modulus and bulk modulus of Tobermorite/UF were lower than that of 'pure' Tobermorite, whereas the tensile strength and failure strain of Tobermorite/UF were higher than that of 'pure' Tobermorite. Moreover, through radial distribution function (RDF) analysis, the connection between Tobermorite and UF found a strong interaction between Ca, N, and O, whereas Si from Tobermorite and N from UF did not contribute to the interface binding strength. Finally, high binding energy between the Tobermorite and UF was observed. The research results should provide insights into the interface behavior between the microcapsule wall and the cement matrix.
基于微胶囊的自修复混凝土能够自动修复损伤并提高混凝土结构的耐久性，其性能取决于微胶囊壁与水泥基体之间的粘结行为。然而，传统的实验方法无法在微观层面提供详细信息。本文通过分子动力学模拟，建立了三种与硅酸钙水化物（C-S-H）凝胶相似的矿物——雪硅钙石（9 Å雪硅钙石、11 Å雪硅钙石、14 Å雪硅钙石）与微胶囊外壳线性脲醛（UF）的复合模型，以研究雪硅钙石/脲醛复合材料的力学性能和界面粘结行为。结果表明，雪硅钙石/脲醛的杨氏模量、剪切模量和体积模量均低于“纯”雪硅钙石，而雪硅钙石/脲醛的拉伸强度和破坏应变则高于“纯”雪硅钙石。此外，通过径向分布函数（RDF）分析发现，雪硅钙石与脲醛之间的连接在Ca、N和O之间存在强烈相互作用，而雪硅钙石中的Si和脲醛中的N对界面粘结强度没有贡献。最后，观察到雪硅钙石与脲醛之间具有较高的结合能。研究结果应为深入了解微胶囊壁与水泥基体之间的界面行为提供参考。
