Preparation of ultra-light ceramic foams from waste glass and fly ash

Ultra-light ceramic foams were successfully prepared by a green spheres technique, which used waste glass powder and fly ash as the main material. Besides, borax and SiC were introduced as fluxing agent and foaming agent, respectively. The effects of fly ash content, borax content and sintering temperature on the microstructures and properties of ceramic foams were systematically investigated. The optimum composition is 30 wt-% fly ash, 70 wt-% waste glass, 15 wt-% borax and 0.5 wt-% SiC. Ultra-light ceramic foams sintered at 680-780 degrees C possess bulk density of 0.14-0.41 g cm(-3), porosity of 82.9-94.1%, compressive strength of 0.91-6.37 MPa and thermal conductivity of 0.070-0.121 Wm(-1) K-1, respectively. This method is convenient, low-cost and environment friendly, which makes it a promising way for recycling solid wastes.