Effect of calcined kaolin clay on mechanical and durability properties of pet waste-based polymer mortar composites

This study attempted to prepare a novel polymer mortar (PM) composite comprising unsaturated polyester resin (UPR) derived from polyethylene terephthalate (PET), as a replacement for cement; calcined kaolin clay as a filler; and silica sand as an aggregate. The UPR resin was synthesized by depolymerizing PET waste using propylene glycol and modifying it with styrene (UPR1) and methyl methacrylate (UPR2) monomers. Most previous studies have focused on the effect of kaolin clay filler on the properties of Portland cement concrete, whereas the effect of kaolin clay filler and sand grading on the properties of UPR resin PM has not been examined. In this study, the effects of UPR1 (UP:styrene) resin, UPR2 (UP:MMA) resin, calcined kaolin clay, and silica sand (zones I, II, and III) on the mechanical and durability properties of a PM composite were investigated. The polymer mortar (PM) mixture design was optimized through the design of the experiment (DOE) using Taguchi and ANOVA analyses. The compressive, tensile, and flexure strengths of the UPR2 PM formulation increased by 19.48, 25, and 28.21 %, respectively, compared to UPR1 PM. In addition, UPR2 PM with 20 % kaolin clay and sand (II) exhibited a decrease in water absorption, mass loss, and loss in compressive strength by 28.20, 15.90, and 7.31 %, respectively, compared to PM containing 18 % kaolin filler and sand (I). Moreover, the experimental results indicated that sand grading significantly influenced the properties of the UPR PM composite. The UPR resin prepared from waste PET and modified using MMA can be successfully used as a binder in PM composites to prepare mortar for interior decoration, repairing, grouting, and lightweight precast products in construction applications.