Evaluation of the Pozzolanic Activity of Copper Slag through Paste and Mortar Studies

Abstract

Ferrous and non-ferrous slags generated in huge quantities in the past few decades as a result of increased demand for metals. Slags from non-ferrous metallurgy can be of interest to find their potential application in construction to solve the problems related to dumping, disposal, environmental issues, etc. The current work focuses on understanding the reactivity of non-ferrous copper slag (CS) when used as a supplementary cementitious material (SCM) for partial replacement of ordinary Portland cement (OPC) 53 grade. Raw granular CS was processed in a laboratory ball mill to obtain finer powdered material. Well-established pozzolanic material, Fly ash (FA) was used in the study for comparing the reactivity of CS. Reactivity studies were carried out on CS-calcium hydroxide (CH) (in suspension) and OPC-CS pastes through the thermogravimetric analysis (TGA) technique. A mortar sample study was performed for the determination of compressive strength with 25% weight replacement of CS and FA in OPC. Mortar samples were steam cured for 12 h at 65 ℃ to check the effect on early age strength development. Compressive strength was determined at the age of 1, 7, 28, and 90 days. CS consumes CH as observed from the results of the paste study. Results indicate that CS does show pozzolanic properties. The reactivity of FA was higher compared to CS as evident from paste and mortar studies. CS-incorporated mortar samples achieved about 80% of the compressive strength compared to the control sample (100% OPC) strength at 90 days of testing.