Investigation of self-healing capability on surface and internal cracks of cement mortar with ion chelator

Abstract Ion chelator is a novel crystalline admixture which can promote the self-healing of cracks in cement-based materials. In this paper, the self-healing capability of the surface and internal cracks of mortars with ion chelator of different age were investigated by the change of crack width, water permeability, recovery of compressive strength and X-ray computer tomography test. The results indicated that the surface crack up to 0.4 mm on the mortars with 0.5 wt% ion chelator pre-cracked at different age can be repaired after standard curing for 30 d. According to the water permeability test, the mortars with ion chelator pre-cracked at 3 d and 28 d have excellent self-healing ability for internal cracks, and the relative permeability coefficient of the mortars with 0.5 wt% ion chelator decreases most significantly. The compressive strength recovery test of mortars shows that ion chelator can promote the self-healing of internal cracks within the mortars. After curing for 56 d, the compressive strength recovery ratio of the mortars with 0.5 wt% ion chelator pre-loaded at 28 d reached 99.5%. And the X-ray computer tomography displayed that the self-healing process of cracks in mortars was from outside to inside.