C-A-S-H Thermoelastic Properties at the Molecular and Gel Scales

Abstract

Data on C-A-S-H (calcium aluminate silicate hydrate) thermoelastic properties is a critical input for multiscale approaches aiming at understanding the thermo-mechanical behavior of cement systems with partial substitution of ordinary Portland cement with supplementary cementitious materials. Molecular simulations at finite temperature are deployed to compute the elastic constants, coefficient of thermal expansion, and heat capacity of C-A-S-H. The heat capacity is calculated following a recently proposed hybrid approach well-suited for hydrated minerals. With this approach, quantum corrections are added for the dry mineral, whereas confined water heat capacity is accounted for through full classical computations. The coefficient of thermal expansion of C-A-S-H is estimated for the first time. Using homogenization theory, the effective properties are computed at the gel scale as a function of the packing density using as input the properties computed at the molecular scale. Our results show good agreement with available experimental data.