Sulfate Resistance and Drying Shrinkage of Self-Compacting Concrete Incorporating Copper Slag

Abstract

This research involved a detailed laboratory study of sulfate resistance and drying shrinkage of self-compacting concrete (SCC) mixes made with copper slag. After an initial curing of 28 days, SCC samples were subjected to a sulfate solution for a period of over 1 year. Changes in compressive strength, mass gain, and expansion measurements were reported for SCC samples. Comparative analysis of compressive strength was done with the respective water-cured samples for up to 1 year. Drying shrinkage of SCC was studied for up to 448 days. Statistical significance of the compressive strength of SCC mixes was determined using analysis of variance. No major catastrophic damage was reported. An improvement in compressive strength of SCC mixes was observed from 28 to 90 days. Peaks of Ca and Si under energy-dispersive spectroscopy analysis revealed the development of calcium silicate hydrate layers leading to a gain in strength. No major phase change under X-ray diffraction (XRD) was observed for SCC mixes under normal curing as well as under sulfate attack. Minute expansions were reported for SCC mixes with copper slag. SCC mixes containing up to 60% copper slag gave lower drying shrinkage values than control SCC mix. The results of compressive strength of SCC exposed to sulfate were found out to be statistically significant.