Properties of Concrete Made from Cupola Furnace Slag and Recycled Construction Aggregates

The replacement of traditional constituents of concrete with waste has garnered a lot of interest due to the increasing demand for natural resources used in concrete production. Hence, this study presents the outcome of an experimental investigation on the effect of partial replacement of Ordinary Portland Cement (OPC) at percentage levels of 0% to 25% in steps of 5%, partial and complete replacement of sand and granite in the percentage of 0 to 50 in steps of 10% with cupola slag and recycled construction aggregates. The fresh and hardened properties of concrete such as workability, compressive strength, and microstructural characteristics were assessed. The test results showed a decrease in workability as the percentage replacement of cupola furnace slag (CFS) and recycled construction aggregates (RCA) increases. Concrete produced at 28 days from the partial replacement of cement and sand with cupola slag has an optimum compressive strength of 20.37 N/mm2 at 10% and 22.81 N/mm2 at 20%, resulting in improved strength of 29.4% and 56.82%, respectively when compared with the control. In contrast, granite’s partial replacement with coarse cupola slag and complete replacement of sand and granite gave a lesser compressive strength when compared with the control samples at 7, 14, 28, and 56 days. The porosity of the concrete with optimum compressive strength from each mix was studied using microscopic and image analysis. The result showed that the addition of cupola slag in granulated and fine forms decreases the porosity, hence leading to higher compressive strength.