Moisture movement in early-age concrete under cement hydration and environmental drying

Abstract

This paper focuses on improving the knowledge of moisture movement and simulation of concrete at early age. In the modelling, self-desiccation due to cement hydration and the non-linear moisture capacity of cementitious materials are considered. A model based on the degree of cement hydration is used to model the reduction in internal relative humidity due to cement hydration. A three-parameter model that is suited to a wide range of water-to-binder ratios of concrete is used to simulate moisture capacity. To verify the model, a series of tests to measure the internal relative humidity of three kinds of concrete under drying and sealing conditions is conducted. Through comparing the model and test results of humidity profiles, the moisture-dependent diffusivity of the three concretes is obtained. Owing to adequate consideration being given in the model to both moisture loss resulting from cement hydration and moisture capacity, the moisture diffusivity of the concrete obtained is less than that determined in previous investigations. The developed moisture movement model and finite-difference method can predict well the moisture distribution and its variations with time.