Preparation and characterization of vitrified tiles from kaolinite clay – waste container glass mixture by sintering method

In this study, vitrified ceramic tiles were made by sintering a mixture of recycled waste container glass powder (RWGP) and kaolinite clays sourced from Nigeria. Initially, waste container glass (transparent color) was obtained from a municipal waste deposit, washed, and crushed before fine milling and sieving to obtain RWGP of approximately 75 µm. Prior to use, the as-received kaolinite clays were also beneficiated and sieved. Three body mixes (VT1, VT2, and VT3) containing 80 – 90 wt. percent RWGP with kaolinite clays and feldspar were homogeneously blended and compacted in a steel mould measuring 200 x 180 x 10 mm. The green compacts were allowed to dry at room temperature before sintering at 1200oC for 2 hours. To evaluate the properties of the developed vitrified tiles, physical, mechanical, phase, and microstructure investigations were carried out. The results showed that bulk density increases across the series, while porosity was 0.5 percent for all tested samples, which is in accordance with ISO 13006. VT2 had higher hardness (6.71 MPa) and compressive strength (2.44 MPa). Quartz and wollastonite were the major phases identified by XRD, with albite, orthoclase, and calcite also present. The microstructure revealed a densified morphology typical of a clay–quartz structure, with little glassy phase resulting from the limited reaction of glass with the clay during sintering.