LAUSR

Abstract Destabilization and release of bound chloride ions in reinforced concrete structures can cause accelerated corrosion of steel bars, posing an attendant risk to the durability of the whole structure and this problem is exacerbated by the combined effect of SO42− and electric field. In this paper, electrochemical chloride removal (ECR) method was used to remove chloride ions from mortar specimens and the influence of four cations (Mg2+, Ca2+, Na+ and K+) on the stability of bound chloride ions in cement mortars simultaneously under an electric field and SO42− attack was investigated. The results showed that bound chloride ions were prone to converting into free chloride ions under the combined effect of electric field and SO42− attack. Moreover, divalent cations (Mg2+ and Ca2+) exerted a more negative effect on the stability of bound chloride ions than monovalent cations (Na+ and K+). X-ray diffraction (XRD) analysis and thermal gravimetric and differential thermal gravimetric (TG-DTG) analysis demonstrated that the destabilization of bound chloride ions under an electric field was mainly attributed to the decomposition of the C-S-H gels and Friedel’s salts. Findings from this research shed new light on the fate of bound chloride ions in reinforced concrete structures under an electric field in chloride-sulfate coexistence environments.