Sinai basaltic rocks and bypass cement dusts from the Misr Beni Suef plant in Egypt were examined for use in the preparation of technical glass-ceramic materials. Cement kiln dust generated during the manufacturing of Portland cement was used in glass batches, in amounts ranging between 10-50% of the batch constituents. Batches were melted and then cast into rod and disc shapes and subjected to heat treatments. Techniques used in the present study included differential thermal analysis, x-ray diffraction, microhardness indentation, and assessment of bending strength, water absorption, density and chemical durability. The obtained glass-ceramic materials were mainly composed of diopside, gehlenite, magnetite and anorthite with a uniform crystal size of less than 150 nm as shown by SEM. The final materials possessed high values of mechanical properties, hardnesses ranging from 4•1-6•8 GPa, bending strengths ranging from 75-135 MPa, with high chemical durability and zero water absorption, which would allow them to be used in many applications, such as building materials, ceramic tiles, etc.

The effect of CaO∖SiO 2 molar ratio on the electrical properties of some glass materials was examined, using the impedance spectroscopy, at different frequency ranges, from 100 Hz up to 5 MHz. Also, a trial was accomplished to study the influence of CaO∖SiO 2 molar ratio on some physical properties such as density, micro-hardness and bending strength. Six glass batches, based on Sinai basaltic rocks and bypass cement dust, were prepared with different CaO/SiO 2 molar ratios (0.2–0.93 mol %). Accordingly, the electrical properties (conductivity dielectric constant and dielectric loss) of these samples show noticeable change. Electrical results show that the samples with relatively low (CaO/SiO 2 ) molar ratio have relatively higher electrical conductivity, compared to the other samples with higher (CaO/SiO 2 ) molar ratios, at different frequencies. Also, at the same time, the bending strength and Vickers micro-hardness show a gradual increase from 56 to 118 MPa and from 4020 to 6120 MPa, respectively, with decreasing CaO/SiO 2 molar ratio. The density of the samples shows a successive increase from 2.79 to 2.96 gm/cm 3 with the successive additions of bypass cement dust.

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Fiber glass waste (FGW) was subjected to alkali activation in an aqueous solution with different concentrations of sodium/potassium hydroxide. The activated materials were fed into a methane–oxygen flame with a temperature of around 1600 °C. X-ray diffraction analysis confirmed the formation of several hydrated compounds, which decomposed upon flame synthesis, leading to porous glass microspheres (PGMs). Pore formation was favored by using highly concentrated activating alkali solutions. The highest homogeneity and yield of PGMs corresponded to the activation with 9 M KOH aqueous solution.