Glass–ceramic foams from waste glass and natural red soil

Abstract

In this study, waste glass obtained from a discarded green glass bottle and unexploited natural red soil (RS) were prepared to get glass–ceramic foams. Red soil is an earthy material, which is used as a foaming agent. A mixture of starting powders containing different mass fractions (5–16 wt.%) of RS with particle size smaller than 20 μm was uniaxially pressed (at 30 MPa), and the obtained compacts were fired at different temperatures (750–850 °C) and holding time (30–120 min). Furthermore, the influences of temperature, holding time, and natural rock additions on the structure, type, and size of pores, besides physical and mechanical properties of the processed foamed glass–ceramic samples, were investigated. The results show that the optimum foaming temperature was found to be 800 °C leading to a maximum value of porosity as high as 90%, while the bulk density and compressive strength reached the values 0.26–0.75 g·cm⁻³ and 1.2–6.1 MPa, respectively. Based on the present data, the obtained glass–ceramic allowed the preparation of different porosity types. Therefore, they provide practical value for specific applications where thermal insulation is desired.