Effect of polymer type and sand/cement ratio on the performance of two-component ceramic tile back side adhesive

The enhancing effect of two-component ceramic tile back side adhesives (BSAs) with the change of polymer type, sand ratio, and cement ratio on the tensile bond strength of cementitious tile adhesives (CTAs) under four curing conditions was investigated. Through optical microscope and scanning electron microscope (SEM) observation, the functioning mechanism of BSA was also investigated. The results show that two-component BSA overwhelms one-component BSA in improving the tensile bond strength of CTAs to tiles. Polymer type plays a key role in achieving high performance BSA, where styrene-acrylate ester (SAE) copolymer is more preferred than styrene-butadiene (SB) copolymer. Both sand and cement additions help promote tensile bond strength under certain curing conditions. Their effectiveness and efficiency show a strong correlation with the choice of polymer type. Through using two-component SAE-based BSA with the right combination of cement and sand ratio, it is possible to strengthen a low-quality adhesive mortar into one with around 1.0 MPa or above tensile bond strength under different curing conditions. The phenomenon is explained by the microstructure change at interfaces.