Enhancing densification and mechanical performance of extruded red ceramics through flat glass waste incorporation

The incorporation of industrial waste into structural ceramic materials represents a relevant strategy for improving resource efficiency in the construction sector. This study assesses the influence of flat glass waste (FGW) incorporation on the thermo-physical behavior, densification mechanisms, and mechanical performance of red ceramic bodies. Specimens were manufactured by extrusion under industrially representative conditions with FGW contents of 0%, 10%, 15%, and 20%, and sintered at 800 °C, 900 °C, and 1000 °C. Raw materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS) to correlate chemical composition and microstructural features with macroscopic properties. FGW incorporation promoted liquid-phase formation during sintering, enhancing vitrification and accelerating densification. As a result, apparent porosity and water absorption decreased consistently with increasing glass content and firing temperature, while bulk density and mechanical strength increased. The formulation containing 20% FGW sintered at 1000 °C exhibited the highest strength values, exceeding standard requirements for structural ceramic bricks and complying with specifications for roofing tiles. Although higher glass contents and firing temperatures led to increased linear shrinkage, the presence of FGW reduced clay plasticity and improved drying stability, indicating favorable processing behavior. Overall, the results demonstrate that waste flat glass can be effectively incorporated into red ceramic bodies to produce higher-performance building components, with clear implications for structural ceramic applications. • Flat glass waste (WFG) acts as an effective fluxing agent in extruded red ceramics • WFG incorporation promotes early liquid-phase formation and accelerates densification • Ceramics with 20% WFG meet both structural brick and roofing tile requirements • WFG addition reduces clay plasticity and improves the stability of the drying stage • Optimal performance is achieved at 1000 °C with 20% WFG via microstructural consolidation