Use of copper slag and cement by-pass dust as cementitious materials

Copper slag (CS) and cement by-pass dust (CBPD) are by-products of the production of copper and cement, respectively. In the Sultanate of Oman, large quantities of copper slag (60,000 tons/year) and cement by-pass dust (25,000 tons/year) are produced every year, most of which is not effectively utilized and disposed on-site without any reuse. The main objective of this research is to investigate the potential use of copper slag and cement by-pass dust in concrete as partial replacements for Portland cement. The physical and chemical properties of both slag and cement by-pass dust were determined. Mortar samples were prepared using different proportions of slag, cement by-pass dust and lime, which was used as an activating material. Proportions up to 15% of Portland cement replacement were used. In addition, a control mixture containing 100% Portland cement was prepared for comparison. Results obtained indicated that the increase in the proportions of copper slag and cement by-pass dust alone resulted in a decrease in the compressive strength of mortars compared with the control mix. The highest compressive strength was achieved in samples containing 5% CBPD + 95% cement, which was 41.7 MPa after 90 days. The optimum copper slag and cement by-pass dust to be used is 5%. In addition, it was determined that using cement bypass dust as an activating material will work better than using lime. Additional studies should investigate the strength and durability when copper slag and cement by-pass dust are used in concrete mixes.