Effect of Powder-Liquid Ratio and Admixture on Properties of Metakaolin-Based Geopolymer Coating

Protective coating is one of the effective ways to help concrete structures resist environmental erosion. However, most of the existing coating materials are organic compounds, which have the disadvantages of poor durability and high energy consumption. In this study, metakaolin with excellent durability was used as the main raw material, and a flexible and waterproof ethylene-vinyl acetate emulsion was added to improve the high brittleness characteristics of metakaolin, resulting in a metakaolin-based geopolymer coating material. Through tests such as water absorption, hardness, gloss, and tensile properties, we investigated the effects of the powder-liquid ratio and the type and amount of admixture on the properties of the coating. The results show that the coating exhibits better performance when the powder-to-liquid ratio is 0.6. Based on this, it was found that the optimal dosage of water-reducing agent, coupling agent, and defoamer was 0.7%, 0.3%, and 0.3%, respectively.