Unveiling the structural and optical properties of fly ash and ceramic waste geopolymers for sustainable construction

This study investigates the potential of ceramic waste as a sustainable alternative to fly ash in geopolymer production, enhancing its mechanical, structural, and optical properties. Geopolymers, environmentally friendly substitutes for Portland cement, help reduce CO2 emissions and pollution. Ceramic wastes, including floor, roof, and sanitary tiles, were explored for their suitability in replacing fly ash. Structural analysis through X-ray diffraction and Fourier transform infrared spectroscopy showed changes in all geopolymers’ crystalline structure and bonding behavior. The study found differences in vibrational characteristics, dielectric properties, and optical behavior, with ceramic waste-based geopolymers exhibiting slightly lower compressive strength than fly ash-based ones. These differences are influenced by crystal defects, bonding strength, and particle size, which affect how the material interacts with heat and electromagnetic fields. The variation in dielectric response and energy loss behavior suggests ceramic waste incorporation can tune the material’s electromagnetic absorption and structural stability, offering potential in functional applications. Among all ceramic waste precursors, roof tile-based geopolymer exhibits the highest compressive strength (34 MPa), a denser microstructure with fewer defects, and higher LO and TO peak intensities, indicating a more extensive three-dimensional aluminosilicate network formation. The study highlights the potential of ceramic waste for improving geopolymer performance and advancing sustainable building materials.