The Influence of Agro-Forestry Wastes Additive on the Thermal Insulating Properties of Osiele Clay
The influence of Agro-forestry wastes additives on the insulating properties of Osiele clay for the production of high quality insulating refractory bricks was investigated. The clay sample from Osiele, Abeokuta in Ogun State, Nigeria was crushed, pulverized, sieved and its chemical composition, apparent porosity and bulk density were determined. The clay sample blended in different proportions with binder and rice husk, coconut shell, saw dust and maize cob were moulded into refractory bricks of 100 mm x 25 mm x 24 mm. The bricks were subjected to thermal shock resistance, linear shrinkage, thermal conductivity, and cold crushing strength tests. Mineralogical analysis and micro-structural examination of the bricks were conducted. The chemical composition result indicates that the clay belong to alumino-silicate group while the basic mineralogical contents are quartz, corundum and mullite. It was observed that the bricks produced with mixture of clay and coconut shell possessed the highest cold crushing strength and bulk density. However, the bricks exhibit lowest linear shrinkage and moderate porosity. The SEM micrograph revealed the formation of mullite phase in the bricks sintered at 1150oC. The results therefore indicate that the clay blended with coconut shell, are most suitable for the production of insulating refractory bricks.