The effect of fluidized fly ash on the properties of dry pressed ceramic tiles based on fly ash–clay body

Abstract Stoneware clay (40 wt.%), classical high-temperature fly ash and fluidized fly ash from two different power plants used in various mixing ratios were the base raw materials for the mixture for production of dry pressed ceramic tiles of the BIII group according to EN 14411. The influence of an increasing addition of fluidized fly ash in the raw material mixture and the granulometry of fly ashes (milling) on the properties of the fired fly ash–clay body have been studied after firing at 1080 °C (water absorption, bulk density, apparent density, apparent porosity and bending strength). Fluidized fly ash reduces firing shrinkage and increases the porosity of the body, which is more remarkable when non-milled fluidized fly ash is used. It is possible to use max. 20 wt.% of fluidized fly ash in the fly ash–clay mixture so that the properties of the fired body meet the requirements of the BIII Group for a body of dry pressed ceramic tiles. The fluidized fly ash dramatically increases the content of sulphur dioxide in flue gases during the firing.