Upcycling glass wool and spodumene tailings in building ceramics from kaolinitic and illitic clay

With concerns related to the high cost and environmental footprint of energy, reducing the sintering temperature in the ceramic industry remains a key challenge. This study investigates the effect of glass wool waste on the sintering properties of kaolinitic and illitic clays, two types of clay commonly used in the ceramic industry. Both clays were substituted with 20 and 40 wt% glass wool, and the effect on sintering at 850, 950, and 1050 °C was investigated. The properties of the sintered materials were assessed with several techniques, including X-ray diffraction, scanning electron microscopy, bulk density, water absorption, dilatometry, and compressive and flexural strength. The water absorption of the prepared ceramics varied from 0 to 30 %, while compressive and flexural strength were in the ranges of 10–60 MPa and 2–15 MPa, respectively, depending on the glass wool content and sintering temperature. The addition of glass wool induced more glass formation, microstructure densification, and higher firing shrinkage at lower temperatures, which contributed to an increase of more than 100 % strength at 850 °C. The addition of 10–20 parts spodumene tailings was observed to mitigate the firing shrinkage at 950 °C with no significant effect on the mechanical properties.