A coupled thermo-hygro-chemical model for characterising autogenous healing in ordinary cementitious materials

Experimental work has demonstrated that cracks can be healed in ordinary cementitious materials in the presence of water. The primary healing mechanisms are hydration of the unreacted nuclei of cement particles and the long-term formation of calcite. A mathematical model for simulating early-age autogenous healing of ordinary cement-based materials is proposed, which employs a coupled thermo-hygro-chemical (THC) framework and which uses a reactive water transport component to predict the movement of healing materials. A single concentration variable is employed for the healing component of the model that is derived directly from the quantity of unreacted cement and computed using a generalised cement hydration model component. The hydration component is directly linked to an expression for capillary porosity and for the porosity of the material within a healed crack. The results from a series of model simulations are in good general agreement with experimental data from tests on autogenous healing.