Waste to valuable resource: application of copper slag and steel slag in concrete with reduced carbon dioxide emissions

Waste recycling and reuse is an important component of sustainability. Extensive research is being conducted to address this issue by incorporating industrial by-product such as steel slag, copper slag, fly ash, ferro-chrome slag, and so on into the construction industry. Steel slag, which is mostly calcium carbonate, is created as a by-product of the steel oxidation process, whereas copper slag is created as a by-product of the metal smelting process and copper refining, with annual production of 12 and 2 million tonnes, respectively. The percentage of aggregates used in concrete is more than 70%, and the augmentation of construction has compelled suppliers and scholars to use alternate aggregate materials that could protect natural resources and the environment. Various studies on the possible use of copper and steel slag in concrete have been conducted in the literature, but studies using a combination of copper and steel slag including ecological and environmental aspects are few. The objective of this investigation is to produce concrete by replacing fine aggregate and coarse aggregate with copper slag and steel slag. After 7, 28 and 56 curing days, the mechanical properties of the various proportions were found and an analogy was drawn with conventional concrete. The experimental findings reveal that the concrete blend with 75% and 25% replacement of fine and coarse aggregate with copper and steel slag, respectively, shows better results in comparison with other mixes. This mix provides 48% lesser cost than control concrete and has 34.9% less embodied carbon dioxide emission, and hence it is recommended as most sustainable and cost-effective concrete. Utilization of copper slag and steel slag in making this sustainable concrete blend will pave path to a safe environment and protection of natural resources.