Foam glasses made from waste flat glasses and sugar beet factory lime with the addition of borax and water glass

Abstract

Foam glass is a lightweight and high-strength material that can be used for thermal and acoustic insulation. Foam glass with suitable properties for use as an insulating material was prepared using waste flat glass, a glass waste not normally used for the production of glass foam, and sugar beet factory lime (S), a CaCO3-rich waste, as a novel foaming agent.Three mixtures were prepared: Glass powder mixed with S (FG-S), glass powder mixed with S and borax (FG-S-B), and glass powder mixed with S and water glass (FG-S-WG). The mixtures were homogenized, pressed into pellets in a hydraulic press, and foamed at 800 °C for 30 min. The prepared samples were characterized mechanically, thermally, and microstructurally. All samples exhibit very low crystallinity. FG-B has the lowest total porosity but much higher compressive strength than FG-S and FG-S-WG. In addition to the total porosity, the pore size distribution of the samples also has a strong influence on the compressive strength. FG-S-B has smaller pores compared to FG-S and FG-S-WG, where the intense foaming of S and water glass leads to the rupture of the pore walls and their coalescence. The thermal conductivity follows the same trends as the total porosity. FG-S and FG-S- WG have a thermal conductivity of 0.044 W/m.K and FG-B has 0.059 W/m.K. All samples have good thermal properties as insulators, but FG-S-WG has poor mechanical properties.