Meso-scale simulation of thermal fracture in concrete based on the coupled thermal–mechanical phase-field model

Abstract

Temperature-induced concrete fracture is a multi-field coupled process and the propagation of crack is complex because of the nonhomogeneity of materials. In this paper, the mesoscale concrete containing aggregate, interfacial transition zone (ITZ), and mortar is established using the random generation algorithm. The governing equations of the coupled thermal–mechanical phase-field model are established, and the finite element method is implemented to solve these equations. Several representative numerical samples are solved by the proposed coupled model, such as concrete under tension after high temperature, concrete spalling caused by high temperature, concrete cracking caused by the temperature rise of a circular hole, and cracking of confined concrete. Numerical results have shown that concrete cracks first appear at the ITZs and eventually develop into one or more major cracks. Most numerical results indicate that the influence of the length scale in the proposed phase-field model on crack propagation is little. It has shown that the application of the phase-field model to simulate mesoscale concrete fracture problems under multi-field coupling is feasible.