Influence of Inorganic Compounds on Self-Repairing Capability and Frost Resistance of Concrete Incorporating Ion Chelating Agent

Abstract

An ion chelating agent (ICA) is a penetrating crystalline additive that can facilitate the closure of concrete cracks. To boost the self-repairing capability of internal damage in concrete and increase its frost resistance, ICA and different types of inorganic compounds (sodium silicate and magnesium fluosilicate) are added. Visual crack closure, water permeability rate, compressive strength loss and reserved ratio, pore structure change, and chloride diffusion coefficient increase rate were used to investigate the influence of ICA and inorganic compounds on the self-repairing capability and frost resistance of concrete. The sodium silicate and ICA had been proven to have the greatest effect on improving the self-repairing capability and frost resistance of concrete. After 28 d of curing, the 0.49 mm-wide surface crack on the concrete containing sodium silicate and ICA was fully repaired, and the water permeability rate was reduced to 0. After 300 freeze-thaw cycles, the compressive strength loss ratio, chloride diffusion coefficient increase rate, and harmful pores proportion of the concrete mixed with sodium silicate and ICA were reduced by 44.3%, 51.7%, and 76.6%, respectively, as compared to the control concrete. Curing for 28 d after freeze-thaw damage, in comparison to the control concrete, the compressive strength reserved ratio of concrete incorporating sodium silicate and ICA increased by 38.5%, and the chloride diffusion coefficient increase rate and the harmful pores proportion decreased by 68.5% and 84.9%, respectively. Furthermore, SEM-EDS revealed that concrete containing ICA and sodium silicate had a large amount of calcium carbonate and a small amount of sodium silicate on the crack surface, and that the internal damage was repaired primarily by a combination of calcium carbonate and hydration products, such as ettringite and calcium silicate.

Keywords: Ion chelating agent, Self-repairing capability, Inorganic compound, Frost resistance, concrete