Molecular material modeling of cement paste composite in shock loading

The effects of molecular features such as phase composition and distribution on the macroscopic behavior of cement paste (CP) subjected to shock waves are still unknown. This study uses molecular dynamics simulations to predict CP’s constitutive material models with different compositions under longitudinal plane shock waves. The CP models are composites of two phases: the main hydrated phase calcium silicate hydrate (CSH) and one unhydrated calcium silicate phase (tricalcium silicate C₃S or dicalcium silicate C₂S). The Hugoniot pressure parameters are derived from isothermal pressure-specific volume relations, the bulk modulus, and the Grüneisen parameter, relative to phase compositions. These parameters are estimated using an isothermal hydrostatic compression model and thermal variations under constant volume. Further, predicted Birch-Murnaghan equations of state established that the bulk modulus of CP increases with the content of unhydrated phases. Also, the Grüneisen parameter of CP is reported for the first time in this research.