A macroscopic poromechanical model of cement hydration

摘要

This paper describes a macroscopic model of the chemo-thermo-poromechanical behaviour of a hydrating cement paste. The hydrating cement is viewed as an open hardening porous medium. The increments of elastic and viscoelastic strain, pore pressure, temperature and hydration degree are related to the increment in total stress and porosity during an infinitesimal transformation. The tangent material properties depend on the current degree of hydration. The. complex chemical reactions are lumped in a single macroscopic one with its kinetics modelled phenomenologically. The in-balance between the decrease of porosity and the consumption of water responsible for self-desiccation, if no water is provided to the paste, is consistently taken into account. A phenomenological relation between capillary pressure and saturation allows reproducing the shrinkage strain associated with self-desiccation. The resulting model is qualitatively calibrated on a set of experiments available in the literature and is shown to reproduce autogenous shrinkage.