Production of Thermal Insulating Material Using Scoria

Abstract

Insulation of the combustion chambers has continued to gain prominence over time because of the desire to improve the thermal efficiency of the systems. The present study investigated the suitability of scoria as an insulating material. Three different batches of scoria, clay and naphthalene were mixed. Scoria served as the matrix, clay served as the binder and naphthalene as the pore creator. The first batch contained 17.6% clay, the second contained 30%, while the third batch contained 39.1%. From each batch, test samples were prepared at varying percentage naphthalene content. Test samples were moulded into different shapes, depending on the test to be carried out on them. They were then allowed to dry under ambient air. This process was followed by oven-drying for 2 hours at 110^oC to further reduce the moisture content of the test samples. The test samples from batch 1 disintegrated during the drying stage leaving only batches 2 and 3. The test samples were thereafter fired in an electric kiln to a temperature of 1000 ºC. Following the firing process, test samples from batches 2 and 3 were subjected to apparent porosity, bulk density, thermal shock resistance and thermal conductivity tests. At 40% naphthalene addition, the percentage apparent porosity values obtained for batch 2 and 3 test samples were 73.13% and 63.23%. Bulk density values at the same naphthalene addition were 1.27 and 1.36 gcm^-3 respectively. Between 0% and 40% naphthalene addition, the thermal conductivity values for batches 2 and 3 test samples steadily reduced from 0.14 - 0.04 W/m.K and 0.27 – 0.09W/m.K. The thermal shock resistance of the test samples from batches 2 and 3 also decreased from 12 to 7 and 13 to 6.5 cycles respectively. Test samples produced from batch 2 produced better results overall, which proved scoria to be suitable for use as a thermal insulating material.