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 900 degrees C 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 (similar to 2 g cm(-3)), accompanied by a Young's modulus of similar to 40 GPa and a bending strength of similar to 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.