A coupled chemo-mechanical phase field model of sulfate induced cracking in concrete with porosity evolution

Abstract

Understanding the crack patterns of concrete under sulfate exposure is essential for revealing the mechanisms of durability degradation caused by external sulfate attack. While previous models have contributed significantly to simulating sulfate-induced damage, the characteristic crack morphologies observed in practice have not been fully captured. This paper presents a chemo-mechanical phase field model to investigate cracking in concrete subjected to external sulfate attack. The developed model successfully reproduces the characteristic ring-shaped cracking pattern by capturing the coupled processes of sulfate diffusion, chemical reactions, porosity evolution, and damage development. The competing effects of the pore filling effect of expansion products and the pore enlargement effect of damage can be obtained by linking porosity with precipitation and cracking. The equivalent inclusion theory is employed to evaluate the eigenstrain induced by the formation of gypsum and ettringite. The phase field regularized cohesive zone model is used to track the crack propagation. The model is validated in terms of sulfate transport and sulfate-induced cracking, showing good agreement with the experimental data. A parametric study is conducted to investigate the effect of the C<inf>3</inf>A content, surface sulfate concentration, and aggregate volume fraction. Results indicate that damage degree in concrete increases with higher initial C<inf>3</inf>A content and surface sulfate concentration, while higher aggregate volume fraction localizes crack propagation near the surface. The proposed model provides insights into the mechanisms of sulfate-induced deterioration and can serve as a predictive tool for assessing concrete durability.