Inhibition resistance and mechanism of migrating corrosion inhibitor on reinforced concrete under coupled carbonation and chloride attack

Abstract

Corrosion of steel bars in the marine environment is an important reason to reduce the service life of reinforced concrete structures. In this study, an amino alcohol migrating corrosion inhibitor (MCI) was coated on the concrete surface, which was then subjected to a simulated marine atmospheric environment by carbonation and salt spraying. The carbonation depth, chloride concentration of concrete, electrochemical performance of steel bars and mass loss rate of steel bar were determined to evaluate the corrosion inhibition performance of MCI. NELD-BS610 hardened concrete bubble spacing coefficient analyzer and scanning electron microscopy (SEM) were applied to analyze the pore structure parameters in concrete and the corrosion behavior of steel bar, respectively. The test results showed that MCI could alleviate the deterioration of concrete induced by accelerated carbonation and chloride attack, and delay the carbonation effect. After 7 days of accelerated carbonation and 35 days of chloride attack, the carbonation depth and chloride concentration of concrete coated with MCI were 16.07% and 16.93% lower than those of concrete uncoated with MCI, respectively. MCI could migrate to the steel bar surface of steel bar to form a protective film, significantly improving the electrochemical performance of the steel bar, and the inhibition efficiency of MCI was about 66.07 ∼ 97.91%. Besides, MCI could also reduce the mass loss rate of steel bars and porosity of concrete induced by carbonation and chloride attack. For the specimens coated with MCI, the mass loss rates of steel bar decreased by 20.31 ∼ 39.78%, and pores with sizes of 1.0 ∼ 0.2 μm in concrete reduced by 59.10 ∼ 76.38%. The results of this research are purposeful for alleviating the corrosion damage problems of reinforced concrete in marine areas.