Waste derived glass ceramic composites prepared by low temperature sintering/sinter-crystallisation

Glass-ceramics based on iron rich wastes were produced by direct sintering and by following an innovative approach, combining direct sintering and sinter-crystallisation processes. According to the second method, a layered tile was manufactured by single firing at 9008C using a selected combination of wastes for both the porous body and the dense coating layer. The coating layer ('glaze') results from the sinter-crystallisation of a waste derived glass mixed with zircon and recycled borosilicate glass. The glaze sealed the porosity of the body and enhanced both mechanical properties and chemical stability. The results show a near to zero water absorption rate, despite a low geometric density (∼2 g cm-3), accompanied by a Young's modulus of ∼40 GPa and a bending strength of ∼30 MPa. The chemical stability of the glass-ceramics thus developed was assessed by the application of a toxicity control leaching procedure. Furthermore, cell culture tests were carried out to evaluate the potential cytotoxicity of the materials