JSTE_V3_N3_RP3 Jagmeet Dhanoa Jaspal Singh Manpreet Kaur Journal on Structural Engineering 2320 - 2343 3 3 25 33 Compressive strength, Copper slag, Fly ash, X- ray diffraction The present investigation assesses the incorporation of industrial waste copper slag and fly ash in concrete. The combined effect of copper slag (CS) and fly ash (FA) as a partial replacement of cement on the compressive strength of concrete has been investigated. The hydration of cement with CS and FA was investigated through X-ray diffraction (XRD). Fifteen mixes were prepared at different replacement levels of CS (0%, 5%, 10%, 15% & 20%) and FA (0%, 5% & 10%) with cement. Results indicate that the compressive strength of concrete decreases as copper slag content increases for all curing ages. The reduction in compressive strength is minor up to 10% of copper slag but beyond 10% of copper slag, there is significant reduction in compressive strength. The addition of FA with 5% and 10% of CS slightly reduces the compressive strength, but addition of fly with 15% and 20% of CS considerably reduces the compressive strength of concrete. XRD showed that the addition of fly ash with 10% of copper slag slightly reduced the hydration of cement, but the addition of fly ash with 20% of copper slag significantly reduced the hydration of cement. The combination of (10% CS + 10% FA) is recommended as maximum replacement of cement. September - November 2014 Copyright © 2014 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=3063