Ceramics-Silikáty 65, (1) 90 - 97 (2021)

Calcium silicate hydrate (C-S-H), as the main product of cement hydration, has an important influence on the cement s structure and properties. In this study, the molecular dynamics method was used to simulate the adsorption process of water molecules on C-S-H. The chemical bond and chemical formula structure of the C-S-H model were analysed. The adsorption characteristics of the water molecules on the C-S-H and the influence of water molecules on the structure of the C-S-H were investigated when the calcium-silicon (C/S) ratio range was 0.67-1.67. The results show that the C/S ratio has a great influence on the adsorption of the C-S-H. When the C/S ratio ˃ 1, the maximum number of adsorbed water molecules increased with an increase in the C/S ratio, but decreased when the C/S ratio ˂ 1. This law was related to the degree of the charge balance of the C-S-H. The C/S ratio has little effect on the adsorption rate of the water molecules. The molecular dynamics behaviour of the C-S-H was analysed on an atomic scale, which laid the foundation for selecting cement-based materials with an optimal C/S ratio in practical engineering.