Analysis of Utilisation of Copper Slag as a Partial Replacement for Cement and Sand in Concrete Mix

Abstract

The increasing demand for construction materials has led to the depletion of natural resources and significant environmental concerns, particularly due to excessive use of cement and river sand. This study investigates the use of copper slag as a partial replacement of cement and fine aggregate in concrete to promote sustainable construction practices. An experimental program was planned using M25 grade concrete with two different replacement levels: 7% cement and 20% sand, and 10% cement and 25% sand. Concrete specimens were prepared and intended to be tested for compressive strength at 7 and 28 days of curing. Based on the expected performance and trends observed in previous studies, the mix containing 7% cement and 20% sand replacement is anticipated to show improved compressive strength due to better particle packing and reduced voids. However, higher replacement levels may lead to a slight reduction in strength because of excess slag content. The study highlights the potential of copper slag as an eco-friendly material that can reduce environmental impact while maintaining acceptable strength characteristics. This approach contributes to sustainable construction by minimizing the consumption of natural resources and industrial waste utilization.

Introduction

This study focuses on the use of copper slag as a sustainable alternative material in concrete production to reduce environmental problems caused by excessive cement consumption and river sand mining. Concrete, being the most widely used construction material, contributes significantly to carbon dioxide emissions through cement production, while sand extraction damages river ecosystems. To overcome these issues, industrial by-products such as copper slag are being explored as eco-friendly substitutes in concrete.

Copper slag, a by-product of copper smelting and refining, possesses favorable properties such as high density, low water absorption, and good durability, making it suitable as a partial replacement for cement and fine aggregate. The present study investigates the effect of replacing cement and sand in M25 grade concrete with copper slag at two proportions: 7% cement with 20% sand replacement, and 10% cement with 25% sand replacement. The main objective is to evaluate the compressive strength, workability, and overall performance of copper slag concrete compared to conventional concrete.

Previous research indicates that copper slag improves concrete properties up to an optimum replacement level. Studies by Al-Jabri et al. (2009), P. M. Rao (2022), and others found that copper slag enhances workability due to its smooth texture and low water absorption. It also improves compressive strength, durability, resistance to chemical attack, and reduces permeability. However, excessive replacement levels may lead to reduced performance, highlighting the importance of optimum dosage.

The materials used in the study include Ordinary Portland Cement (OPC 43 grade), natural river sand as fine aggregate, crushed granite or basalt as coarse aggregate, and copper slag. Copper slag is a black, glassy granular material mainly composed of iron oxide and silica, with high specific gravity and very low water absorption, which contributes to denser concrete.

The experimental methodology involved preparing three concrete mixes: a control mix without replacement, a mix containing 7% cement and 20% sand replacement with copper slag, and another with 10% cement and 25% sand replacement. Standard concrete cubes of size 150 mm × 150 mm × 150 mm were cast, compacted, demoulded after 24 hours, and water-cured. Workability was assessed using the slump cone test, where higher slump values indicated improved workability.

Compressive strength testing was conducted using a Compression Testing Machine (CTM) according to IS: 516 standards. The concrete cubes were tested after 7 and 28 days of curing by applying load gradually until failure, and compressive strength was calculated from the maximum load sustained by the specimen.

Conclusion

Based on the experimental investigation, it can be concluded that the use of copper slag as a partial replacement of cement and fine aggregate has a significant effect on the compressive strength of concrete. The results indicate that the mix containing 7% cement and 20% sand replacement (M2) achieved the highest compressive strength at both 7 and 28 days compared to the control mix. The improvement in strength is attributed to better particle packing, reduced voids, and enhanced bonding within the concrete matrix due to the presence of copper slag. However, further increase in replacement level to 10% cement and 25% sand (M3) resulted in a slight decrease in strength, although it remained comparable to conventional concrete. Thus, it can be concluded that the optimum replacement level of copper slag is around 7% for cement and 20% for fine aggregate. The use of copper slag not only improves the mechanical properties of concrete but also contributes to sustainable construction by reducing the consumption of natural resources and utilizing industrial waste effectively. Workability improved with the incorporation of copper slag due to its smooth texture and lower water absorption, resulting in better flowability and ease of mixing. The M2 mix showed optimum slump value, while excessive replacement in M3 slightly increased workability but may affect mix stability.

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Copyright

Copyright © 2026 Abhay Chaurasia, Amit Kumar Mishra, Prachi Singh, Atul Pal, Dilip Maddheshiya, Shakti Kumar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.