Synergistic effect of ion chelating agent and magnesium fluorosilicate on self-repairing ability and microstructure of mortar

Abstract

Ion chelating agent (ICA) can stimulate the self-repairing of cracks and pores in concrete. In order to further improve the self-repairing capability of cement-based materials, the ICA and different dosage of permeable crystallization surface treatment agent (magnesium fluorosilicate) were mixed into the mortar. The compressive strength recovery, pore-size distribution, crack self-repairing and repair product of the mortar were studied. The results showed that after pre-loading 70% of the failure strength, the compressive strength recovery rate of mortar containing ICA and 0.50 wt% magnesium fluorosilicate was 24.4% higher than that of the control mortar. At 28 d, the ratio of harmful pores (pore diameter >0.1 µm) of mortar with ICA and 0.25 wt% magnesium fluorosilicate was decreased by 62.6% compared with the control mortar. The crack with a maximum width of 0.60 mm in mortar incorporating ICA and 0.5 wt% magnesium fluorosilicate could be completely repaired within 28 d. In addition, scanning electron microscope and energy dispersive spectrometer revealed that a lot of calcites in the crack of mortar mixed with ICA and magnesium fluorosilicate, which proved that the ICA and magnesium fluorosilicate had synergistic effect on the self-repairing properties of cement-based materials.