On the phase-field modeling of fully coupled chemo-mechanical deterioration and fracture in calcium leached cementitious solids

Abstract

As it is extremely difficult, if not impossible, to carry out fully coupled chemo-mechanical tests lasting several hundreds of years, a reliable modeling approach is thus indispensable in assessing the integrity, durability and safety of infrastructures under aggressive aqueous environments. In this work, we propose a multi-physical phase-field model for fully coupled chemo-mechanical deterioration and fracture in calcium leached cementitious solids, aiming to predict the long-term behavior of concretes structures. The chemical sub-problem is built upon the mass conservation of calcium ions in pore solution, representing the diffusion–dissolution equilibrium of the leached system. Regarding the mechanical process, the length scale insensitive phase-field cohesive zone model is substantially extended with the calcium dissolution induced deterioration of mechanical properties properly accounted for by a porosity-dependent damage variable. Vice versa, during the leaching process both the transport diffusivity of calcium ions and the dissolution rate of the skeleton are promoted with the crack phase-field incorporated into the chemical sub-problem. The resulting inter-field fully coupled model is validated by several representative numerical examples. Both the sequentially and fully coupled chemo-mechanical problems are studied to verify the detrimental effects of simultaneous chemical attack and mechanical loading on the structural behavior. Based on the fully coupled analysis, an extra example is presented to demonstrate the promising prospects of the proposed model in service-life predictions of concrete structures under concurrent mechanical loading and aggressive environmental attacks.