Fabrication and Properties of Self-foamed Glass Ceramics from Red Mud and Ceramic Tile Polishing Waste

Self-foamed glass ceramics were fabricated using red mud and ceramic tile polishing waste as main starting materials. Effects of red mud content in ceramics, sintering temperature and soaking time on pore structure, pore size distribution, total porosity, compressive strength and thermal conductivity were elaborately investigated. Experimental results revealed that the as-prepared self-foamed glass ceramics all exhibited homogenous foam-like structure. When the red mud content rose from 15 to 25 wt% and then up to 30 wt%, mean pore size and total porosity of the samples increased markedly and then decreased sharply, while compressive strength and thermal conductivity first decreased and then increased. As sintering temperature rose from 1110 to 1140 degrees C and soaking time extended from 30 to 60 min, respectively, mean pore size and total porosity increased remarkably, while compressive strength and thermal conductivity decreased appreciably. The self-foamed glass ceramics from 25 wt% red mud sintered at 1130 degrees C for 45 min exhibited many excellent properties including mean pore size of 0.99 mm, bulk density of 0.48 g/cm3, total density of 79.6%, high compressive strength of 8.3 MPa and low thermal conductivity of 0.08 W/m K, which made the as-fabricated self-foamed glass ceramics a good candidate material for external thermal insulator in buildings.