Effect of MgO addition on sinterability, crystallization kinetics, and flexural strength of glass–ceramics from waste materials

In this work, the effect of MgO addition on the sinterability and crystallization of sintered glass–ceramics prepared from powder mixtures of waste glass and fly ash was investigated. The bulk density of the glass–ceramics decreased with increasing the MgO content, reaching the maximum value at the sintering temperature of 1000 °C. The amounts of the glass-ceramic crystalline phases, i.e., pyroxene and forsterite, increased with the MgO content. Furthermore, when the MgO content increased from 5 to 25 wt%, the crystallization mechanism changed from bulk to surface crystallization. The flexural strength was significantly influenced by three factors, i.e., porosity, crystallinity, and crystal shape anisotropy, and reached the maximum value of 78 MPa for a 10 wt% content of MgO. Fast sintering promoted the densification process, thus increasing the glass-ceramic flexural strength. As a result, owing to their high strength and relatively low density, these sintered glass–ceramics appear promising for potential applications in lightweight construction tiles.