Modelling of the hydration and moisture transfer coupling effects on the microstructure properties of the concrete cover

In this research, a model of the couplings between hydration and moisture transfer within cementitious materials is proposed. Based on taking into account the microstructure properties and the moisture transfer properties due to hydration, the model describes the couplings between the moisture transfer at early-age owing to external drying and the internal water depletion by hydration. Furthermore, the slowing down of the hydration kinetics caused by the decrease of relative humidity prevailing in the pores is also investigated. Experimental data, such as drying kinetics, as well as porosity and degree of hydration profiles, are used to verify the proposed modelling. The materials used here are three OPC cement pastes with different water-to-cement ratios. The agreement between observed and modelled results is considered satisfactory and confirms the possibilities of using the coupling model to simulate moisture transfer for cementitious materials at early-age.