The dissolution process of calcium hydroxide into solution and the precipitation process of calcium carbonate are controlled by a solute concentration field that is continuous at solid-liquid interface. Then, a model is developed by incorporating the chemical reaction kinetics, diffusion and thermodynamics, and numerically implemented by the finite element method (FEM) within the MOOSE framework. We further investigate the microscopic crack morphology by performing multiple simulations with the parameter informed from the experimental tests.
By using this method, the concrete healing interface can be easily tracked, and the geometry of the interface can be accurately described. This has important guiding significance for the implementation and optimization of self-healing technology in practice.
There are already several modelling approaches available for simulating the self-healing behaviour of concrete, but only a few models simulate the evolution of self-healing products from the perspective of the prevailing reaction mechanisms, thermodynamics and chemical kinetics. The phase field method has been applied to various phenomena in materials research, such as, solidification, solid-state phase transformation, recrystallization, grain growth, and fracture. The classical phase-field method is formulated based on the theory of thermodynamics and can be employed to solve morphological evolution processes, which are rather difficult to achieve through traditional sharp interface models. It is worth noting that, solidification and precipitation processes are quite similar to many solute-solvent systems, like self-healing process in cement based composites actually are. There are various studies on self-healing mechanisms and microstructure evolution, which provide an overview of the use of phase-field methods.