不同钙硅比水化硅酸钙力学性能的分子动力学模拟

Molecular Dynamics Simulations of Mechanical Properties of C-S-H Structures with Varying Calcium-to-Silicon Ratios

基于Pellenq等的建模思路,构造了不同钙硅比(C/S)的水化硅酸钙(C-S-H)原子模型,采用分子动力学方法模拟了C-S-H在轴向拉伸载荷作用下的力学性能。重点比较分析了不同钙硅比的C-S-H在无水及含水情况下的拉伸应力-应变曲线。模拟结果表明:(1)与钙硅比为1.0的情况相比,钙硅比大于1.0时C-S-H结构的抗拉强度显著下降;(2)钙硅比大于1.0时,钙氧间的相互作用在承受载荷方面起重要作用,有效弥补了结构中因SiO_2基团缺失引起的缺陷,使得C-S-H的强度下降程度趋缓;(3)当应变达到一定程度时,水分子能够切断钙氧间的相互作用,使得C-S-H结构的强度进一步降低甚至引起断裂失效。

The atomic structures of calcium silicate hydrate(C-S-H)with varying calcium-to-silicon(C/S)ratios were constructed by the cCSH models of Pellenq et al.,and the mechanical properties of C-S-H structures under tensile loading were investigated using molecular dynamics(MD)method.The results from the molecular dynamics simulations showed that the tensile strength was decreased significantly when the C/S ratio was greater than 1.0,compared to the case of C/S=1.0.The interaction between calcium atoms and oxygen atoms played an important role under loading,which made up the shortfall caused by the lack of SiO_2,and the decrease of the strength of C-S-H in the case of C/S>1.0 became slow.The water molecules helped to cut off the interaction between calcium atoms and oxygen atoms at a certain deformation degree,which reduced the strength of C-S-H till to the failure mode.