Assessment of self-healing performance of cement-based materials incorporating ion chelator and industrial wastes

Ion chelator can enhance the self-healing of cracks and pores in concrete. To further improve the self-healing capability of cement-based materials, different industrial wastes (i.e. fly ash, limestone powder and blast furnace slag (BFS)) and ion chelator were mixed into mortar. The crack closure index, water permeability, water absorption, impermeability, compressive strength recovery and healing products of mortar were studied. The results showed that the mortar mixed with BFS and ion chelator possessed the best repair ability on cracks, the crack with a maximum width of 0.55 mm can be closed within 14 d. Meanwhile, the water permeability and water absorption of mortar incorporating ion chelator and BFS were obviously smaller than that of control mortar. After curing for 56 d, the chloride diffusion coefficient of mortar containing ion chelator and BFS was reduced by 73.7% compared with control mortar. The compressive strength recovery ratio of mortar containing ion chelator and BFS was 63.7% greater than that of control mortar after pre-loading 80% of the failure strength. In addition, scanning electron microscopy and energy dispersive spectroscopy displayed a large number of calcites at the edge of crack section in mortar containing ion chelator and BFS, the inside of crack was mainly repaired by the combined effect of calcium carbonate precipitation and hydration product.