Soda-Lime and Borosilicate Glass Waste as Precursors for Sustainable Geopolymers

This study reports the synthesis and characterization of geopolymers produced by using borosilicate and soda-lime glass wastes as partial substitutes for conventional geopolymer raw materials. The glass wastes were characterized by XRF, XRD, FTIR, and SEM/EDS, revealing high silica content and predominantly amorphous structures, indicating their suitability for geopolymer applications. Geopolymer formulations were prepared by partially replacing sodium silicate and metakaolin with glass incorporation levels ranging from 14% to 25%. Compressive strength tests conducted after 7 days of curing showed that soda-lime glass-based geopolymers achieved compressive strengths of approximately 30 MPa at 14% glass incorporation, while borosilicate glass-based systems reached values of up to 32 MPa and maintained strengths comparable to that of the reference matrix at higher replacement levels. XRF, XRD, FTIR, and SEM/EDS analyses confirmed the formation of geopolymeric networks and consistent chemical compositions across the systems. Overall, the results indicate that waste glass can be effectively incorporated into geopolymer formulations under ambient curing conditions, enabling the partial replacement of conventional precursors and providing a comparative assessment of the influence of different glass types on mechanical resistance.