USE OF TANNERY SLUDGE IN CLAY BRICK MANUFACTURING.

The paper analyses the possibilities of recycling tannery sludge (TS) in clay brick manufacture. The physico-mechanical properties and microstructure of clay brick and cement mortars vary depending on TS content in the mix. 2.5%-15.0 TS (by weight) was added to clay bricks fired at 1000 °C temperature and maintained at maximum heat for 1 hour. The tests revealed that 2.5 TS addition had a positive effect on physical and mechanical properties of clay brick: reduce drying and firing shrinkage, reduce water absorption, and increase compressive strength. Chromium leaching values in clay brick (2.5% TS) were found not to exceed the limit values set forth in 2003/33/EC. [ABSTRACT FROM AUTHOR]