低密度和高密度水化硅酸钙的纳米压痕数值模拟

水化硅酸钙(C-S-H)是决定以硅酸盐水泥为主要组分的水泥基材料性能的关键组分，水化硅酸钙(C-S-H)是存在于水化产物中连续的固体物质，占水化水泥浆体体积的50%～60%，是水泥浆体中决定硬化水泥浆体物理结构和性能的主要成分，同时水化硅酸钙(C-S-H)也是混凝土结构宏观尺度的凝聚性和耐久性的重要影响因素．模型的建立对于预测水泥的体积性能如收缩、蠕变、渗透率和裂缝等方面越来越重要．通过将水化硅酸钙(C-S-H)分为低密度和高密度两种数值模型，并且将水化硅酸钙(C-S-H)视为在纳米尺度上具有实际微观粒子性能的离散颗粒的集合，运用分子动力学方法，通过控制水化硅酸钙(C-S-H)的紧密堆积体积分数和保持颗粒级别的其他材料属性不变来进行纳米压痕实验模拟，进而验证了压痕模量和硬度符合纳米压痕实验数据的规律．

Numerical Simulation of Nanoindentation for the LD and HD Calcium Silicate Hydrates

Calcium silicate hydrate(C-S-H) is the key component to determine the performance of the Portland cement based material C-S-H is a continuous solid material in hydration products. It accounts for 50%~60% of the hydrated cement slurry volume. C-S-H is the main ingredient to decide the hardened cement slurry’s physical structure and performance. At the same time, C-S-H is one of the important influential factors for concrete structure coherence and durability in macro view. Models became increasingly important to predict the bulk properties of cement and concrete, such as shrinkage, creep, permeability and cracking. Two numerical models were presented respectively for the low-density and high-density C-S-H gel phases in cement paste. C-S-H was introduced as an assemblage of discrete granular particles at nanoscale with realistic particle-level properties. With the molecular dynamics method, nanoindentation simulation was performed on each phase. Through control of particle volume fraction of C-S-H and with the other particle-level material properties kept constant, the results further show that the indentation modulus and hardness conform well to the law of the data from nanoindentation experiments in literature.