A multi-scale approach for simulation of capillary absorption of cracked SHCC based on crack pattern and water status in micropores

Abstract

Strain-hardening cement-based composites (SHCC) under cracked condition exhibit distinct behaviour of capillary absorption because of multiple fine cracks and complicated crack patterns. Past studies for estimating capillary absorption of cracked SHCC mainly focused on evaluating the results by total gravimetric weight. In addition, the average values of crack width and crack spacing were often used to characterize crack patterns. In this study, a multi-scale approach for numerical simulation of the capillary absorption of cracked SHCC is proposed by considering the detailed crack patterns such as the width and location of each crack. Water flows in bulk matrix and multiple cracks are simulated using two individual transport equations. Water absorbed from a crack to its adjacent matrix is treated as the mass exchange of the two equations, taking into account pore structure and water status in the bulk matrix as well as the damage level of the crack surfaces. Analysis is firstly carried out for SHCC with uniform crack width and crack spacing, showing consistent results with test data of previous studies in which the total absorption increased with decreasing crack spacing. Analysis for SHCC with non-uniform crack widths and locations, furthermore, exhibit significant water penetration at crack zones. Other factors, such as relative humidity for pre-drying, specimen height, water-to-binder ratio, and fibre content, are also discussed in the analysis. This approach enables the estimation of water profile of cracked SHCC, so can be used for further crack-linked process, for example, chloride penetration or self-healing.