Effects of styrene-acrylic emulsion on mechanical properties and hydration characteristics of polymer-cement waterproofing coatings prepared with various cement types

The mechanical properties of polymer-cement waterproofing coatings (JS waterproof coatings) are significantly impacted by the type of cement employed. In this study, three JS waterproofing coatings were developed by integrating styrene-acrylic emulsion (SA) with Portland cement (PC), white Portland cement (WPC) and sulfoaluminate cement (CSA), respectively. The tensile properties and water absorption of these coatings were evaluated. In addition, the effect of SA on the hydration processes and products of the various cements was investigated using calorimetry, X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The results indicate that JS waterproofing coatings formulated with PC and WPC exhibited superior elongation at break, while those incorporating CSA demonstrated significantly higher tensile strength and reduced water absorption. The addition of SA was found to significantly inhibit the dissolution of C3A and C3S phases in PC and WPC, thereby prolonging the induction period of cement hydration and reducing the formation of ettringite (AFt). In contrast, CSA exhibited rapid reactivity, with ion dissolution rates surpassing the adsorption capacity of SA, resulting in extensive AFt formation within JS waterproof coatings. These AFt crystals integrated into the coating’s organic matrix, forming a reticulate network that enhanced tensile strength and significantly improved waterproofing performance.