Preparation of glass-ceramic materials from granitic rocks waste

Crystallisation of glasses based on the diopside-anorthite eutectic system, containing increased amount (10–50 wt.%) of wollastonite based on granite quarries waste, was investigated for the preparation of cheap technical glass-ceramic materials. Granite quarries waste consisted of about 52 wt.% of the batch constituents depending on composition. The granite quarries waste composition was sometimes modified by adding other ingredients such as dolomite, limestone and Al2O3. Batches were melted and then casted into glass, which was then subjected to heat-treatment to induce crystallisation. The resulting glass-ceramic materials (heat-treated at 1000 °C for 3 h) were mainly composed of diopside, anorthite, wollastonite and mullite. With increasing temperature (to 1050 °C for 3 h), diopside and anorthite transformed into akermanite and mullite. It has been found that increasing the content of the diopside-anorthite eutectic in the batch constituents, resulted in increased bulk crystallisation. Samples were characterised with different techniques including differential thermal analysis, polarizing microscope, X-ray diffraction and indentation microhardness testing. The obtained glass-ceramic materials possess very high hardness, indicating high abrasion resistance, making them suitable for many applications under aggressive mechanical conditions.