An experimental investigation on longevity and mechanical characteristics of high-performance concrete incorporating copper slag as replacement of fine aggregate

Abstract The mechanical and durability characteristics of high-performance concrete (HPC) that incorporates copper slag from the metallurgical industry’s redox are investigated in this study.By substituting conventional concrete components with sustainable alternatives such as microscopic silicon fume, fly ash, and copper slag, the research aims to enhance mechnaical , durability performance while reducing environmental impact. Strength of compression, split tensile capacity, flexural strength and durability parameters like resistance to acidic resistance, absorption of moisture, porosity, and invasion of chloride were all assessed experimentally. Concrete mixes containing copper slag (CS) showed differing strength efficacy in comparison to the control mix after 28 days of curing. With increases of 13.29% in compressive strength, 23.57% in split tensile strength, and 40.00% in flexural strength, the M2 mix with 40% CS replacement demonstrated the greatest improvement. Additionally, the M1 mix (20% CS) showed favorable strength increases in every parameter. Nevertheless, compressive and split tensile strengths decreased with replacement levels beyond 40%, with significant drops seen at 80% and 100% CS substitution. Up to 80% CS, flexural strength was improved; however, after full replacement, it declined. In order to maximize mechanical performance at 28 days, an ideal CS replacement amount of 40% was found.In addition, long-term durability assessments highlighted the competence of copper slag-based concrete as a high-performing and environmentally friendly material for contemporary building.Additionally, a thorough evaluation of the embodied carbon of the component materials was carried out to provide a deeper knowledge of their environmental consequences, while microstructural characterisation was executed to examine the presence of crystalline phases such as calcium silicate hydrate (C–S–H), ettringite, portlandite and unhydrated cement compounds, confirming the heterogeneous microstructure of the concrete sample. This study highlights the potential of copper slag as a sustainable substitute for fine aggregate in concrete, providing better strength performance while cutting waste production, protecting natural resources, and reducing the carbon footprint of building operations. The results validate its use in infrastructure, maritime, and structural projects.