Porcelain Stoneware Tiles Based on Clays Mixture and Recycled Waste Glass Powder: Effect of Soaking Time

The effect of soaking time on the properties of porcelain stoneware tiles based on clay mixture and recycled waste glass powder was studied. Mixture was prepared and fired at 1150 degrees C. During firing, raw mixture was subjected to various soaking times: 30, 60, 90 and 120 min. The by-products were characterized by their linear shrinkage, water absorption, bulk density, flexural strength, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results were modelled by using different mathematical expressions. The results demonstrated that physico-mechanical properties of ceramic probe are significantly affected by soaking time. After 30 min, products satisfied the ISO 13006 standard condition for porcelain stoneware wall and floor tiles: water absorption value was lowest (0.07%) and mechanical strength value was 44.4 MPa. Prolonged soaking time was undesirable due to its negative effect (bloating) on the products' physical and mechanical performance. The XRD patterns indicated the presence of mullite, cristobalite, enstatite, anorthite, hematite and quartz as the main crystalline phases. SEM images of the tiles fired at 1150 degrees C for 30 min display a very close texture and dense microstructure.