A model for coupling hydration-drying of concrete cover

After the formwork removal, the concrete is submitted to important early-age coupling between hydration, drying and heat transfer, which can lead to shrinkage and to the cracking of reinforced concrete structure. Firstly, a model is developed to predict the hydration process for several main species of clinker, taking into account three stages : induction, nucleation-crystal growth and diffusion of ionic species through the hydrated coating around the clinker grains. Secondly, this model is coupled with a model of moisture transfers in cement-based materials for examining the impact of premature drying on the porosity, the amount of hydrated products and the consumption of water. The model validation is conducted by a comparison between computed and experimental results from the literature as well as an experimental campaign in order to determine the evolution of physico-chemical characteristics of a cement paste during premature drying