Optimized formulation of waterproof coating based on polymer and sodium silicate-activated GGBS using Box Behnken design - Selection of additives

Abstract

Waterproof coating based on polymer and sodium silicate-activated ground granulated blast-furnace slag (PSS-GGBS waterproof coating) is a kind of new two-component waterproof coating, which is expected to have a promising application in building field because of simple construction, high strength, and good durability. Additives plays a vital role in determining the properties of PSS-GGBS waterproof coatings. Thus, the optimum proportion of various additives for the preparation of waterproof coatings was designed via the response surface methodology (RSM) to enhance mechanical properties. Results show that the optimal dosage of the defoamer, silicone leveling agent, and dispersant is accounted for 0.86 wt%, 0.56 wt%, and 0.56 wt% of the liquid phase, respectively. In this case, the tensile strength and breaking elongation of the waterproof coating reach 2.40 MPa and 108.84%, respectively. The experiment results are in full agreement with the corresponding predicted data, and the waterproof coating fulfills the criteria of type Ⅱ in standard GB/T 23445–2009. The crosslinking between polymer latex and sodium silicate activated GGBS was more sufficient after adding additives. The dense C–S–H gels and CaCO3 crystals with a strong mechanical bond, which is due to improvement of the degree of alkali-activated reaction induced by the addition of additives, contribute a high mechanical property to coatings.