Mechanical Properties and Microstructure of Fast – Fired Clinker Tiles Based on Wierzbka I Raw Material

The article presents results of research on microstructural and mechanical properties of floor tiles clinker manufactured on the basis of Wierzbka I raw material, which is part of the deposit Wierzbka, near Suchedniów. Wierzbka I clay was added in various volume fractions to the standard tile compositions used in industrial practice. The samples were pressed in a range of from 21 MPa to 42 MPa and fired in the laboratory furnace at 1130°C to 1190°C. Selected compositions were pressed at 28 MPa and fired in a standard industrial environment. The process of firing was conducted in an industrial kiln at temperature of 1160°C for 38 minutes, with holding for 4 minutes at maximum operating temperature. The samples, which were prepared in the laboratory and industrial conditions were evaluated for the effect of addition of the Wierzbka I clay on their microstructural and mechanical properties based on the measurement results of linear shrinkage, bulk density, open porosity, water absorption and flexural strength (Ϭ) of the tiles. Microstructural changes were observed with a scanning electron microscope (SEM). The results revealed that the tested tiles were characterized by a high degree of sintering, an apparent density of 2.5 g/cm³, an open porosity and water absorption below 0.5%. The measurement results of mechanical bending strength showed that the tested samples had a high strength of 50 MPa.