Development of Alkali-Activated Tiles Based on Metakaolin and Ceramic Tile Waste by Uniaxial Pressing

This study aims to demonstrate the feasibility of transferring alkali activation technology to the ceramic tile production by developing tiles based on metakaolin and ceramic tile waste by uniaxial pressing. Optimization of the tile formulations was achieved by adjusting precursor composition (metakaolin or combination of metakaolin and ceramic tile waste), NaOH molarity, and overall water content. After uniaxial pressing at 50 MPa, alkali-activated tiles were consolidated at 50 °C for 24 h. Physical and mechanical properties were assessed following ISO test methods for ceramic tiles, allowing direct comparison with the ISO classification requirements. The more promising formulations highlight a water absorption by vacuum test method (ISO 10545-3) equal to 15%, thus allowing a BIII classification according to ISO 13006. Finally, thermal stability up to 850 °C was determined, thus allowing alkali-activated tiles to be industrially glazed.