A study of the coefficient of thermal diffusivity of building bricks made from clay and local distillery waste mixture

Abstract

The use of various wastes in clay for brick making has significantly gained research attention. This is because most of these wastes especially organic ones burn during firing leaving pores (voids) in the bricks thus lowering heat flow across such bricks. In this case, bricks can act as insulators in walls thus cutting energy costs in buildings. In this study, the coefficient of thermal diffusivity of bricks made from clay and local distillery waste mixture was investigated. Local distillery waste is the end waste obtained when the crude brew is made from cassava flour mixed with water, fermented, roasted, dried, fermented again, and distilled. The proportion of clay replaced by the local distillery waste in the mixture was 0, 4, 8, 12, 16, and 20 wt.%. The bricks were then fired from 600-1100 °C in steps of 100 for one hour in an electric furnace. The coefficient of thermal diffusivity was calculated from the experimental values of; thermal conductivity which was measured using quick thermal conductivity meter (QTM-500) with sensor probe PD-11, specific heat capacity which was measured by method of mixture and density obtained from measured values of mass and volume of the samples. The study results presented a general decrease in the values of the coefficient of thermal diffusivity as the content of local distillery wastes added to clay increased across all temperatures. The coefficient of thermal diffusivity was observed to steadily decrease from firing temperatures 600 °C through to lowest values at 900 °C. However, there was an increase in the coefficient of thermal diffusivity in a range of 1000 to 1100 °C. An optimal value of 2.36×10-7 m2s-1 at 900 °C was exhibited by samples with 16 wt.% local distillery waste. This value is below the accepted standard of 5.61×10-7 m2s-1. Therefore, local distillery waste is suitable for use in bricks as thermal insulating material