Assessment of tannery sludge additions on physico-mechanical properties of clay bricks

The present study explores the partial replacement of clay by the addition of tannery sludge (TS) and glass in brick preparation. Bricks were prepared with varying weight percentages of TS (9%, 18%, and 27%) along with glass powder (10%) and fired at different temperatures (900, 950, and 1000 degrees C). Water absorption, compressive strength, weight loss on ignition, volumetric shrinkage, and bulk density of the bricks were found to be in the range of 12.3%-16.8%, 2.3-4.5 MPa, 4%-13.8%, 6%-11%, and 1600-1850 kg/m(3), respectively. Heavy metal leaching was observed to be within the limits of United States Environmental Protection Agency 1311 for the prepared bricks. The addition of TS resulted in a decrease of physical and mechanical properties of the bricks due to the decomposition of organic and inorganic compounds. However, the presence of glass powder compensates for the effect of TS by fusion and densification process. The results indicate that hybrid addition of TS and glass can partially replace clay in brick production and effectively immobilize heavy metals.