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.