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The effects of CaO/SiO 2 ratio (basicity) and CaCl 2 addition amount on the properties of CaO–MgO–Al 2 O 3 –SiO 2 –CaCl 2 glass-ceramics (GC) were investigated. When sintered at 825 °C, the increase in basicity from 0.35 to 0.75 reduced the porosity of GCs from 1.1 to 0.8 vol%, but the increase of CaCl 2 addition amount from 5 to 10 wt% increased the porosity from 0.8 to 7.0 vol%. The main crystalline phase of GC changed from augite (Ca(Mg 0 · 7 Al 0.3) (Si 1 · 7 Al 0.3)O 6) to Ca 10 Al 12 Cl 2 Si 5 O 37 by increasing the CaCl 2 addition amount to 7.5 wt%. The increase in CaCl 2 addition had adverse effects on the bending strength and Vickers hardness, while the rise in basicity deteriorated the bending strength but had little impact on the Vickers hardness. This study may have a guiding significance for preparing slag-based GCs and treating CaCl 2 -containing wastes. [ABSTRACT FROM AUTHOR]

CaCl 2 can dissolve in the silicate glasses, and thus, using the CaCl 2 -bearing glass for the preparation of glass-ceramic could be a potential method for treating CaCl 2 -bearing wastes. In this work, two kinds of glass powders, CaO-MgO-Al 2 O 3 -SiO 2 and CaO-MgO-Al 2 O 3 -SiO 2 -CaCl 2 , were sintered at 825–850 ℃ to prepare the glass-ceramic. Besides, a low-pressure (19.1kPa) hot-pressing sintering technology was applied to reduce the porosity and pore size of the glass-ceramic. The addition of CaCl 2 (5 wt%) reduced the polymerization degree, glass transition temperature, crystallization peak temperature, and crystallization activation energy of the glass. Augite was the main crystalline phase of the glass-ceramic, and the addition of CaCl 2 promoted the precipitation of anorthite. The glass-ceramic prepared from the Cl-containing glass always exhibited a higher bending strength than that obtained from the Cl-free glass. When sintered at 825 ℃ for 8 h, the glass-ceramic showed the highest bending strength of 171 MPa. [ABSTRACT FROM AUTHOR]