Waste glass and fly ash derived glass-ceramic

Crystallization behavior of a waste-based glass-ceramic was studied by means of X-ray diffraction analysis, and the surface morphological observations and chemical compositions were evaluated by field emission-scanning electron microscopy and energy dispersive X-ray spectrometry. Applying the mechanical milling method, the glass-ceramic was prepared by using fly ash from a thermal power plant mixed with waste glass cullet. Powder mixtures consisting of waste glass powder (70 wt%) and fly ash (30 wt%) were used to make glass-ceramic. Various heat treatment temperatures [900, 925, 950, 975, 1000 and 1025°C] were used to obtain a glass-ceramic of the optimum crystal phase, mechanical properties and chemical durability. The X-ray diffraction analysis showed that the crystalline phases in the glass-ceramic were diopside [Ca(Mg, Al)(Si, Al)₂O₆], augite [Ca(Mg, Fe)Si₂O₆] and wollastonite [CaSiO₃]. The crystallization of an acicular phase in the matrix was achieved in the heat treatment temperature range of 1000–1025°C, and the acicular type main crystal phase in the glass-ceramic was wollastonite [CaSiO₃]. The heat treatment temperature range [1000–1025°C] also showed much better mechanical properties.