Chloride transportation and electrochemical behavior of concrete containing corrosion-inhibiting admixture and its inhibition mechanism under compound salt and drying-wetting cycles

Abstract

The purpose of this study is to provide an ecological corrosion-inhibiting admixture (CIA) for retarding the degradation of reinforced concrete under compound salt attack and drying-wetting cycles. The effects of CIA on the mechanical behavior, chloride transportation, and electrochemical behavior of concrete under compound salt and drying-wetting cycles were investigated. The pore contents with different sizes in concrete and the micro-morphology of rebars were analyzed by the bubble spacing coefficient analyzer and the scanning electron microscopy (SEM), respectively. The findings showed that the addition of CIA retarded the deterioration of concrete under compound salt and drying-wetting cycles. After exposure for 150 d, the weight loss rate and average free chloride concentration of concrete containing 5 % CIA decreased by 74.14 % and 51.53 % respectively, and the compressive strength was 1.49 times that of concrete without CIA. Chloride transportation was primarily dominated by diffusion and convection. Additionally, CIA significantly reduced the content of larger pores, prevented the diffusion of chloride and sulfate into the interior concrete, and formed adsorption films through a combination of physical and chemical effects, thus improving the electrochemical performance of rebars. This study is of great significance to provide new perspectives and improvement measures for mitigating the deterioration of reinforced concrete under compound salts and drying-wetting cycles.