Utilization of porcelain tile polished waste as an alternative raw material in wall tile bodies

The manufacturing of ceramic tiles generates waste at different stages of the production process. A significant part of these wastes has not been properly used yet; therefore, implementing their use in the production of ceramic tiles as an alternative raw material will help in preserving natural resources, reducing the cost of production, and hence producing an ecofriendly ceramic tile at lower cost. This study examines the feasibility of using polishing waste (PW) coming from the porcelain tile polishing step, as an inert filler agent in a wall tile body mix. Starting from a standard body mix (prepared with 18 wt% pegmatite), several modified body mixes were prepared by adding 6 wt%, 12 wt% and, 18 wt% PW instead of pegmatite. The tile specimens were obtained from compacted uniaxial pressing and fired in air at various temperatures (1100–1140 °C) using a laboratory-scale electric furnace. The technological properties of the fabricated samples, such as linear shrinkage, water absorption, flexural strength, and colour properties, were measured. It was found that the samples containing up to 12 wt% PW and fired at 1140 °C had similar firing shrinkage to the standard wall tile body. The addition of PW does not change the water absorption values but causes an increase in the flexural strength, reaching up to 19.6 MPa. A similar strength value could be obtained at about 20 °C lower firing temperature when 100% of the pegmatite was replaced by PW.