Effect of sintering temperature on mechanical and thermophysical properties of biowaste-added fired clay bricks

This study investigated the thermophysical and mechanical properties of biowaste-added fired clay bricks, which were sintered at two different temperatures in the framework of energy conservation. Tea waste, sawdust and wheat straw were mixed with clay and fired to obtain fired clay bricks at sintering temperatures of 500 °C and 980 °C. Physical characterization of the brick samples showed a linear relationship for loss on ignition, water absorption and porosity with increasing wt% of biowaste at both temperatures. However, a decrease in water absorption, bulk density and porosity with increasing sintering temperature is correlated with an increase in loss on ignition values due to combustible organic nature of the biowaste. The thermal conductivity, thermal diffusivity and specific heat capacity were appreciably decreased with an increase in porosity level and change in mineral composition with sintering temperature. The compressive strength was found to be very low at 500 °C. However, at 980 °C, the compressive strength met the standards set by the Pakistan Building Code. On comparison of the results with commercial bricks, the fired clay bricks having 2–4 wt% of tea waste, 2–6 wt% of sawdust and 1–2 wt% of wheat straw offered good thermophysical and mechanical properties.