Hygro-Gradient Model for Permeability of Unsaturated Cementitious Composites

Abstract

A new method for predicting the water absorption process of unsaturated cementitious composites is proposed, and its functionality is experimentally verified. The mechanism of the capillarity on water absorption process is mathematically termed by a slip boundary condition of micro-flow of pore water, and employed to an unsaturated water permea-tion on the scheme of multi-scale modeling. The rapid sorption just after the exposure to condensed water is fairly simulated owing to the non-local formulation of hygro-gradient, which simply represents the thermodynamics of non-equilibrated states in dry pores. The proposed model of complexity of micro-pore connection is examined in terms of the initial water content, porosity and saturation of micro-pore structure and volume ratio of aggregate. It is further examined in terms of the intrinsic hydraulic profile by using the Boltzmann’s transform.