Epoxy emulsion modified geopolymer coating for long-term corrosion protection of steel

Corrosion of steel in reinforced concrete usually occurs in marine environment. In this study, the fly ash-slag-based geopolymer coating of steel were modified by the epoxy emulsion (EP) as toughening agent. The influence of different EP contents on the interfacial properties of the coatings was investigated through adhesion test and scanning electron microscope (SEM) analysis. To evaluate the anti-corrosion behavior of the coatings, electrochemical measurement was conducted in five typical simulated solutions for three months. The anti-corrosion performance of the coatings was comprehensively assessed by considering the corrosion morphology and corrosion rate of the coated steel samples. The results demonstrated that the 5 % EP-modified geopolymer coating exhibited superior adhesion and corrosion resistance compared to the steel reinforcement. The rust inhibition mechanism of the modified geopolymer coating can be attributed to the dense structure of the geopolymer and the formation of Mg-Al LDH during the geopolymerization reaction.