Performance of Alkali Activated Slag Concrete Mixes Incorporating Copper Slag as Fine Aggregate

Abstract

The present study attempts a detailed evaluation of the strength and durability performance of Alkali Activated Slag Concrete (AASC) mixes containing Copper Slag (CS) as fine aggregate. Copper slag, a waste product obtained from copper industry, is incorporated in the AASC mixes as a partial/full replacement to river sand. Initially OPC and AASC mixes are designed to obtain M45 grade with river sand as aggregate; subsequently additional AASC mixes obtained with CS as fine aggregate, incorporated as replacement to sand at increasing volumes are also considered. CS replacement at varying levels upto 100% by absolute volume, in increments of 25% of total fine aggregate are attempted. Various strength and durability properties, including under flexural fatigue tests, of these AASC mixes are studied in detail and are compared with those of conventional Ordinary Portland Cement Concrete (OPCC). An attempt is also made to study the flexural performance of experimental reinforced concrete beams prepared using such mixes in terms of their Load-deflection response, first crack loads and ultimate loads, ductility characteristics etc. vis-à-vis OPC-based concrete beams with similar reinforcement. The ecological and economical analysis of all such concrete mixes is also carried out. The experimental results indicate that the AASC mixes display better mechanical strength as compared to OPCC in normal working environments. While the AASC mixes with CS fine aggregates displayed similar durability performance in an acid rich environment, however, relatively lower performance is exhibited by them in magnesium sulphate solution and elevated temperatures. The fatigue performance of AASC mixes marginally improved with the incorporation of CS. It was also observed that the fatigue data of beams made with different mixes can be satisfactorily modelled using two parameter Weibull-distribution. The reinforced AASC beams with CS as fine aggregate have exhibited acceptable flexural performance, both with respect to flexural strength and deflection, as compared with AASC concrete beams using river sand fine aggregate. The AASC mixes with CS fine aggregates displayed lower energy requirement and lower production cost as compared to OPCC, thus proving them to be eco-friendly. Thus the experimental results have indicated that CS aggregates can be used as alternate fine aggregates in alkali activated concrete mixes for acceptable performance in both structural and pavement quality concrete mixes.