First-Principles Calculations on Polymorphs of Dicalcium Silicate - Belite, a Main Component of Portland Cement

We investigate systematically the polymorphism of stoichiometric dicalcium orthosilicates C2S using ab initio studies and interatomic potential functions. Apart from the structural data, here, we present the analysis of novel data on phonon dynamics in belite. The latter is related to the number and type of phase transitions in C2S, including the peculiar thermal hysteresis in the route between three low-temperature phases and inverse thermal expansion of the lowest temperature phase. The study on the polymorphism of stoichiometric C2S is the necessary step to understand the behavior of doped belite-based materials.