Heterogeneous Nature of Calcium Silicate Hydrate (C-S-H) Gel: A Molecular Dynamics Study
Heterogeneous Nature of Calcium Silicate Hydrate (C-S-H) Gel: A Molecular Dynamics Study
复制标题
硅酸钙水合物 (C-S-H) 凝胶的非均质性质：分子动力学研究
DOI：
10.1007/s11595-020-2275-8
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发表时间：
2020-04-01
影响因子：
1.6
通讯作者：
Ding, Qingjun
中科院分区：
文献类型：
--
作者：
Jin, Shucheng;Li, Jinhui;Ding, Qingjun
水化硅酸钙（C-S-H）的结构和力学性能在分子水平上充当水泥基建筑材料的“DNA”。为了解C-S-H凝胶的抗加载能力，采用分子动力学（MD）方法对C-S-H凝胶模型进行了沿着x、y、z方向的单轴拉伸试验模拟。由于层状结构的结构和动力学差异，C-S-H模型表现出非均匀的力学行为。在XY平面上，结合力可达4GPa，主要由Ca-O和Si-O离子-共价键提供。硅酸钙板良好的塑性归因于硅酸盐分支结构的形成和层间钙原子的恢复作用。而在z方向上，C-S-H层之间由不稳定的氢键网络连接，其抗拉强度最低，为2.2GPa。这导致在z方向上的脆性破坏模式。相对较低的拉伸强度和在z方向上的塑性差提供了在宏观水平上对水泥材料的拉伸弱点的分子见解。
Structure and mechanical properties of Calcium silicate hydrate (C-S-H) at a molecular level act as "DNA" of cement-based construction materials. In order to understand loading resistance capability of C-S-H gel, research on molecular dynamics (MD) was carried out to simulate the uniaxial tension test on C-S-H model along x, y, and z directions. Due to the structure and dynamic differences of the layered structure, the C-S-H model demonstrates heterogeneous mechanical behavior. On an XY plane, the cohesive force can reach 4 GPa which is mainly provided by the Ca-O and Si-O ionic-covalent bonds. The good plasticity of calcium silicate sheet is attributed to the silicate branch structure formation and the recovery role of interlayer calcium atoms. However, in z direction, C-S-H layers connected by the unstable H-bonds network, have the weakest tensile strength 2.2 GPa. This results in the brittle failure mode in z direction. The relatively low tensile strength and poor plasticity in z direction provides molecular insights into the tensile weakness of cement materials at macro-level.