Effect of Partial Replacement of Fine Aggregate by Tannery Crumb on Mechanical Properties of Concrete

The leather industry is an essential contributor to Bangladesh's economy, but its by-product, tannery crumb, poses severe environmental and health risks due to heavy metal contamination. As such, there is a growing need to develop innovative solutions to manage tannery crumbs and reduce its impact. Therefore, an experimental program was conducted with a mix ratio of 1:1.5:3. The ingredients incorporated in this ratio were OPC cement, Sylhet sand with a fineness modulus of 3.1, and 19 mm downgrade stone chips. The fine aggregate was replaced by volume with tannery crumb at varying percentages of 0, 10, 20, and 30% by volume, while maintaining water-cement ratios of 0.40, 0.45, and 0.50, aimed to evaluate the effect of tannery crumb on the mechanical properties of concrete, including compressive strength ( \({f}_{c}^{\prime}\) ), splitting tensile strength ( \({f}_{ct}\) ), and flexural strength ( \({f}_{r}\) ). The maximum compressive strength was found at 20% tannery crumb with a water-cement ratio of 0.40, resulting in 45.56 MPa and 54.15 MPa at 28 and 90 days, respectively. The maximum splitting tensile strength was found at 20% tannery crumb with a water-cement ratio of 0.45, resulting in 3.23 MPa but strength was 3.12 MPa at a w/c ratio of 0.40 showing a very slight difference. However, the flexural strength decreased with an increase in the tannery crumb and water-cement ratio. The load–deflection curve obtained from the flexural strength test revealed a sudden failure behavior, with no signs of improvement in its inherent brittle behavior. Anyway, all the experimental data from flexural and compressive strength fell within the ACI-mentioned range of 7.5 to 12 \(\sqrt{{f}_{c}^{\prime}}\) .