Pozzolanic Rendering of Lime Sludge and Sandstone Reject Blend

The author has investigated the pozzolanic property of blended industrial rejects collected in sludge form from the textile industry and sandstone quarry. The pozzolanic potential of a blend of rejects was examined at 10, 20, 25, 30 and 35% replacing the primary binder, i.e. cement. The percentage replacement of each material was examined after mechanical treatment, i.e. grinding for 30 min duration. Percentage replacement was carried out based on quantitative presence of SiO2, Al2O3 and Fe2O3 in industrial rejects to meet the requirement of IS 3812: (Part 1) 2013. The Pozzolana Activity Index, Chapelle Activity, and Electrical Conductivity tests were used to verify the pozzolanic ability of the blend. The Lime Sludge Reject (LSR) and Sandstone Sludge Reject (SSR) were characterized physically, chemically and mineralogically. The Ordinary Portland Cement (OPC) control mix will be used to compare the performance of blended concrete. The 28 days characteristic compressive strength (CCS) and durability properties were investigated. The identified industrial reject blend shows the improved pozzolanic efficiency when analysed statistically for optimum replacement of cement to make the cement industry more sustainable.