Novel applications of waste ceramics on the fabrication of foamed materials for exterior building walls insulation

In this paper, a novel fabrication method has been proposed by using waste ceramic and other polishing materials as main raw materials to prepare foam ceramic for the potential applications in thermal insulation of exterior building walls. In particular, the content of Al2O3 and SiO2 was almost 90% in this kind of materials. The polishing materials result from grinding polished tiles into powder and the ceramic foam was foamed slurry produced by self-configure foaming solution after mechanical stirring. Effects of content of foam and clay on the specimens' properties such as compressive strength, apparent porosity, bulk density, water absorption and thermal conductivity were investigated. Based on results, when the content of clay was 10 wt%, the amount of foam was 10 wt%, apparent porosity of specimens sintered at 1000 °C was 50.6%, linear change was 7.2%, bulk density was 0.70 g/cm3, compressive strength was 8.0 MPa, and thermal conductivity was 0.137 W/(m·K) at 200 °C. Microstructures of specimens were also detected and compared, and the exceptional mean pore size was 39.7 μm which was measured by using “Micro-image Analysis and Process System” (MIAPS) software. Due to the difference in bulk density, the internal pore structure and performance of the sample are different. Comprehensive properties of specimens can be optimized by adjusting the amount of foam and clay. The proposed method for obtaining insulation foamed materials using ceramics' waste and other polishing materials was feasible, whilst saving resources and energy.