Multiscale Chemico-Thermo-Hydro-Mechanical Modeling of Early-Stage Hydration and Shrinkage of Cement Compounds

Abstract

The early-stage cement hydration is critical to the strength and durability of cement-based materials. Due to the complex processes involved, holistic multiphysics and multiscale simulation is challenging. This paper introduces the concept of a water characteristic curve (WCC) used in unsaturated soils to cement-based materials. The WCC characterizes the internal structure of cement and essentially relates the pore morphology and physical chemistry of solid-liquid interface in microscale to the concepts of suction and water content in macroscale. A thermo-hydro-mechanical model was developed based on this multiscale technique. A modified Fourier’s heat equation for the thermal field, a modified Richard’s equation for the hydraulic field, and an extended Navier’s equation for the mechanical field were employed for developing the theoretical multiphysics framework. Auxiliary relationships, e.g., temperature-induced flow and chemical-reaction information of cement components, were adopted for the completeness of the formulation. This simulation framework was implemented with the finite-element method. Phenomena such as shrinkage, which is typical of early-stage cement hydration process, were reproduced. The methodology of this model provides a solid cornerstone for the simulation-based prediction of concrete performance.