Rate dependent self-healing model for cementitious materials

Abstract

A new micromechanics-based constitutive model for self-healing cementitious materials is proposed. The model is aimed at self-healing materials with distributed healing mechanisms, such as materials with embedded microcapsules and enhanced autogenous healing capabilities. The model considers anisotropic microcracking and time-dependent healing. In contrast to many existing models for self-healing cementitious materials, the new approach imposes no limitations on the number or timing of microcracking or healing events that can be simulated. The formulation ensures that the simulation of microcracking and healing is always consistent with the second law of thermodynamics. The model is implemented in a three-dimensional nonlinear finite element code that allows structural elements formed from self-healing materials to be simulated. A series of single-point simulations illustrate the versatility of the model. The experiments considered with the model encompass a set of cylindrical specimens formed from concrete with embedded microcapsules containing sodium silicate, and a notched beam test series that examined the self-healing potential of concrete formed with a crystalline admixture. The validations show that the model can capture the characteristic mechanical behaviour of these structural elements with good engineering accuracy.