Effect of Partial Replacement of Fly Ash by Decoration Waste Powder on the Fresh and Mechanical Properties of Geopolymer Masonry Mortar

This study aims to investigate the feasibility of using decoration waste powder (DWP) as a partial replacement for fly ash (FA) in the preparation of geopolymer masonry mortar, and to examine the effect of different DWP replacement rates (0%–40%) on the fresh and mechanical properties of the mortar. The results showed that each group of geopolymer masonry mortar exhibited excellent water retention performance, with a water retention rate of 100%, which was due to the unique geopolymer mortar system and high viscosity of the alkaline activator solution. Compared to the control group, the flowability of the mortar containing lower contents of DWP (10% and 20%) was higher. However, as the DWP replacement rate further increased, the flowability gradually decreased. The DWP could absorb the free water in the reaction system of geopolymer mortar, thereby limiting the occurrence of geopolymerization reaction. The incorporation of DWP in the mortar resulted in a decrease in compressive strength compared to the mortar without DWP. However, even at a replacement rate of 40%, the compressive strength of the mortar still exceeded 15 MPa, which met the requirements of the masonry mortar. It was feasible to use DWP in the geopolymer masonry mortar. Although the addition of DWP caused some performance loss, it did not affect its usability.