不同缺陷结构下水化硅酸钙单轴拉伸性能研究

混凝土作为一种核心建筑材料,其力学性能很大程度上取决于水泥水化产物中水化硅酸钙(C-S-H)的性能。文章基于Hamid提出的无水托贝莫来石结构,通过随机去除硅链中的桥接硅四面体(bridging tetrahedra,BT)和配对硅四面体(paired tetrahedra,PT),构建了具有不同缺陷结构的C-S-H模型。采用此类模型进一步构建了不同钙硅摩尔比的C-S-H扩胞模型,通过几何结构的优化和分子动力学模拟获得不同缺陷结构下C-S-H的拉伸性能,并对3种不同方向上的抗拉性能进行比较。结果表明,不同的缺陷类型对C-S-H的力学性能具有一定程度的影响,为构建更精确的C-S-H分子模型提供了参考。

Concrete, as a fundamental building material, largely owes its mechanical properties to the performance of calcium silicate hydrate(C-S-H), the principal product of cement hydration. Building upon the structure of anhydrous tobermorite proposed by Hamid, this study constructed C-S-H models with varying defect structures by randomly removing bridging tetrahedra(BT) and paired tetrahedra(PT) from the silicate chains. Subsequently, expanded cell models of C-S-H with different calcium-to-silicate ratios were developed based on these models. The tensile properties of C-S-H under different defect structures were obtained through optimization of geometric structures and molecular dynamics simulations, with a comparative analysis of tensile strength in three distinct directions. The results demonstrate that different types of defects have a significant impact on the mechanical properties of C-S-H, providing valuable insights for the development of more precise molecular models of C-S-H.