Effect of Ion Chelating Agent on the Ion Corrosion Resistance of Concrete Partially Immersed in Different Salt Solutions

Abstract

Concrete partially immersed in saline solutions suffers double damage from salt crystallization and harmful ion corrosion. The ion chelating agent (ICA) can stimulate the production of crystalline products to repair concrete damage and densify its structure. Based on this, this paper investigates the influence of ICA on the resistance of concrete partially immersed in different salt solutions ( Na 2 SO 4 solution, NaCl solution, and a composite solution of Na 2 SO 4 and NaCl) to ionic attack by means of mass loss, dynamic elastic modulus, compressive strength, pore size distribution, and internal micro-morphology of the concrete. The results revealed that the Na 2 SO 4 solution eroded the concrete structure most seriously, while the ICA could effectively inhibit the destruction of concrete by the salt solution. After 120 days of soaking in Na 2 SO 4 solution, the mass loss rate and total porosity of concrete with ICA decreased by 23.5% and 13.5%, respectively, while the relative dynamic elastic modulus and compressive strength increased by 8.4% and 25.9%, respectively, in comparison to control concrete. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analyses proved that, although a large amount of expansive ettringite (AFt) and gypsum formed in the concrete with ICA immersed in Na 2 SO 4 solution, leading to the damage of the pore structure of the concrete, crystalline products such as calcium silicate and calcium carbonate were still produced at the pores, slowing down the destruction of the concrete structure by the erosive ions.