Multiphasic model of early stage hydration in concrete using the theory of porous media

Abstract The aim of this paper is to model the behavior of concrete during the initial stage of maturing. Most models consider only thermo-mechanical phenomena assuming the hygral phenomena of less importance due to high liquid saturation. In order to grasp those effects, the proposed model is an extension of Gawin's model (D. Gawin, F. Pesavento, and B. A. Schrefler, Int J Numer Methods Eng 67(3), 299–331, 2006). The fresh concrete, modeled as porous material, is described within the well-founded framework of the Theory of Porous Media. The multiphase material consists of a solid phase representing, for example, cement, gravel, etc., and a fluid and gas phase representing the pores filled with water and dry air. Compared to Gawin's model, here, beside the effect of hydration-dehydration, the effect of evaporation-condensation will be taken into account. A new formulation for the evaporation process in the fresh concrete is proposed and validated by an experimental study. The presented model is implemented in the research code PANDAS. The proposed model investigates and proves the assumption of Gawin's model to have a linear connection between porosity and hydration degree.