Influence of MgAl–NO2-LDHs on passivation of reinforcing steel in simulated geopolymer solution

Abstract

Because of ion exchange properties, the presence of layered double hydroxides (LDHs) influences passivation process of reinforcement embedded in geopolymer concrete. In this study, the ion exchange behavior of MgAl–NO-LDHs and its effect on the characteristics of passivation film and electrochemical behavior of passive reinforcement in simulated slag-fly ash-waste ceramic powders geopolymer solution (SGP) are extensively investigated. The results indicate that LDHs with layered structure improve the protection efficiency of adsorption layer in SGP. Further, the intercalated NO is efficiently exchanged with OH in SGP, thus increasing the thickness and corrosion resistance of the formed passivation film. However, because the adsorption layer halts NO release process, the beneficial effect is mainly observed during later immersion stage.