水化硅酸钙动态力学性能的分子动力学模拟研究

Molecular Dynamic Simulation for Mechanical Properties of C-S-H

对水泥主要水化产物——水化硅酸钙的力学特性进行了分子动力学模拟。采用Hamid 1.1纳米托贝莫来石作为水化硅酸钙的初始结构,通过分子动力学模拟,获得水化硅酸钙的拉伸和压缩应力应变关系,并考虑了应变率和原子数对力学特性的影响。分子动力学模拟研究发现,计算峰值应力、峰值应变都较宏观试验结果高出很多;拉伸峰值应力较压缩峰值应力要小;峰值应力、峰值应变和弹性模量随着应变率的增加而增加,随着模拟晶胞体积(原子数)的增加而降低。研究表明采用分子动力学模拟能获得原子尺度水化硅酸钙动态力学性能,为揭示水泥基材料动态力学性能微观机理奠定了基础。

A molecular dynamic simulation for mechanical properties of calcium silicate hydrate （C S H） is carried out in this paper. C-S-H is the most important products from cement hydration. Hamid 1.1 nm tobermorite is used as the initial structure of C-S-H. Stress-strain relationships of both compressive and tensile behavior are calculated, and the effect of strain rate and number of atoms on the mechanical properties during the simulation is further investigated. Research results show that both the peak stress and peak strain at nano-scale are much higher than that obtained from macro scale experiments. Further simulation of different strain rates and volumes shows that the peak stress, peak strain and elastic modulus increase with the increasing strain rate, while decrease with the increase of volume （atom numbers）. Research results indicate that the mechanical properties of C-S H at atomic scale can be achieved by molecular dynamic simulation. This research also produces a fundamental achievement to reveal the mechanism for dynamic strength increasing of cement based materials at micro scale.