Waste-to-resource preparation of glass-containing foams from geopolymers

Waste glass-based cellular geopolymers with total porosity about ~55 vol%, thermal conductivity of ~0.21 W/mK, and compression strength of ~7.3 MPa were successfully produced by a direct foaming technique using hydrogen peroxide (chemical pore-forming agent) in combination with Triton X-100 (stabilizing agent). Thermal treatment of these porous geopolymers at 700–900 °C resulted in a significant increase in volume (secondary foaming). Interconnected pores with a wide range of sizes, ranging typically from 50 to 3000 µm, formed through this foaming process. Glass and glass-ceramic foams (GFs), possessing high overall porosity (77 < P t < 88 vol%), low bulk density (0.27 < ρ b < 0.48 g/cm 3 ), low thermal conductivity (0.11 < λ < 0.15 W/(m K)), and remarkable compression strength (1.2 < σ < 5.5 MPa), were successfully fabricated through the secondary foaming. The obtained results confirmed that this is a viable method for the waste-to-resource production of glass-based foams