Title: Production of Glass and Glass Ceramics from Industrial Waste System by Using Phase Equilibrium Diagram of CaO-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> System
Abstract: The production of new materials by mixing together two or more raw materials is a useful method of reusing industrial waste. The purpose of this study is to produce glass-ceramics, with wollastonite with superior mechanical and chemical properties, from the industrial wastes of fly ash, concrete sludge, and glass cullet. First, two targets with different chemical compositions were selected from the wollastonite crystallization area in the phase equilibrium diagram of CaO-Al2O3-SiO2, and the mixing ratios of industrial wastes were determined. Some batches were prepared by mixing the wastes at the respective weight ratio. Glass samples were produced by melting the batches at high temperatures and then quenching the melt. The amorphous glasses produced were reheated in a range of crystallization temperatures to convert them to glass-ceramics. The results of SEM observation and X-ray diffraction (XRD) analysis of the produced materials showed wollastonite to be the main crystal, with other crystals of anorthite or calcium silicate. The mechanical and chemical properties of the produced glass-ceramics, i.e., hardness, fracture toughness, and acid resistance, were investigated. It was clarified that the properties were improved after the conversion of the amorphous glass to the glass-ceramic for both types of glass-ceramic, and the wollastonite precipitated glass-ceramic containing a small amount of anorthite crystal exhibited better mechanical and chemical properties than that containing calcium silicate.