Molecular dynamics simulations of Calcium Silicate Hydrates under hydrostatic compression

Ingrid M. Padilla Espinosa and Ram Mohan

Calcium-Silicate-Hydrates (CSH) is the major component in cement paste, representing about 50-60% by volume of the solids. It is the binding phase and it is responsible for strength in cement. However, despite the widespread use of cement paste and the efforts to comprehend its molecular structure and properties, a fully understanding of this material has not been reached. This study aims to investigate the impact behavior of CSH under isothermal hydrostatic compression using molecular dynamics simulations. The response of the material to hydrostatic compression allows to investigate the material behavior under shock wave conditions as expected from earthquakes, explosions or impact. A modified tobermorite structure with calcium/silicon ratio equal to 1.7 was the molecular model representing CSH, and the ReaxFF was used to describe the molecular interactions. The isothermal pressure-specific volume (P-υ) and internal energy-specific volume (ε-υ) relationships were found. The results of the present work show a reasonable agreement with experimental results and can be used to understand the deformation response of CSH, and consequently cement paste, to shock wave conditions.