International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 08 | August 2025
p-ISSN: 2395-0072
www.irjet.net
“INVESTIGATION OF MECHANICAL PROPERTIES OF CONCRETE BY PARTIAL REPLACEMENT OF METAKAOLIN BY CEMENT AND COPPER SLAG BY FINE AGGREGATE USING POLYPROPYLENE FIBERS’’ Sanjay G M1, Ashwin C A2, Vallabha C D3, Pavan4 1 PG Student (MTech) in Structural Engineering, Dr. Ambedkar Institute of Technology, Bangalore, Karnataka,
India
2Assistant Professor ,Department of Civil Engineering,Dr. Ambedkar Institute of Technology, Bangalore,
Karnataka, India
3 PG Student (MTech) in Structural Engineering, Dr. Ambedkar Institute of Technology, Bangalore, Karnataka,
India
4 PG Student (MTech) in Structural Engineering, Dr. Ambedkar Institute of Technology, Bangalore, Karnataka,
India ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - This experimental work examines the
binding component, generates a large amount of carbon dioxide, contributing significantly to environmental pollution. To overcome this issue, researchers have explored the use of supplementary cementitious materials and industrial by-products to partially replace cement and natural aggregates, thereby improving performance and promoting sustainability.
performance of M30 grade concrete produced by partially replacing cement with metakaolin and fine aggregate with copper slag, along with the addition of polypropylene fibres. Basic material tests confirmed the suitability of the constituents: the specific gravity of cement was 3.12, fine aggregate 2.46, coarse aggregate 2.73, metakaolin 2.40, and copper slag 3.74. The fineness of cement was measured as 6 percent, while the standard consistency was found to be 32 percent. Water absorption values were 0.1 percent for fine aggregate and 0.5 percent for coarse aggregate, all within permissible limits. Concrete mixes were prepared with a water–cement ratio of 0.40, cementitious content of 394 kg/m³, fine aggregate 791 kg/m³, coarse aggregate 1068 kg/m³, and admixture content of 1.1 percent by weight of cement. Various mix design was done by partially replacing with copper slag as fine aggregate by a percentage of 40,50,60,70 percent with constant replacement of 10% metakaolin as cement and additionally using polypropylene fibers of 0.8%. Compressive strength and split tensile strength was determined at curing periods of 28 days. Results indicated steady strength development with age, and the optimum mix incorporating metakaolin, copper slag, and polypropylene fibres was also added to the mix achieved a 28-day compressive strength of 35.33 MPa compared to the control mix average of 29.83 MPa and the split tensile strength varied from 2.78(control mix) to 3.2 MPa (50% copper slag,10 metakaolin,0.8% polypropylene fibers) . The study concludes that the combined use of metakaolin, copper slag, and polypropylene fibres improves compressive strength and split tensile strength and provides a sustainable alternative to conventional concrete mixtures.
Metakaolin, obtained through calcination of kaolinitic clay, is a highly reactive pozzolanic material that enhances the compressive strength, durability, and chemical resistance of concrete. It reduces porosity, shrinkage, and permeability, while promoting the formation of additional calcium silicate hydrate. Copper slag, a by-product of the copper smelting industry, provides another sustainable alternative by replacing natural sand. With its high specific gravity and angular particles, copper slag improves density, workability, and strength, while simultaneously addressing waste disposal problems. In addition, polypropylene fibres are widely used to reduce plastic shrinkage cracks, improve toughness, and enhance durability. Even in small dosages, they significantly improve the crack resistance of concrete. In this study, M30 grade concrete was prepared by replacing cement with 10 percent metakaolin, fine aggregate with copper slag at 40, 50, 60, and 70 percent, and by incorporating 0.8 percent polypropylene fibres. Basic material tests such as specific gravity, fineness, water absorption, and consistency were performed to ensure the quality of the ingredients. Concrete cubes were then cast and tested for compressive strength at 28 days to evaluate the effect of these modifications on strength development. The aim of this work is to develop and evaluate a sustainable concrete mix by partially replacing cement with metakaolin and sand with copper slag, along with the addition of polypropylene fibres, in order to enhance compressive strength and improve the overall performance of M30 grade concrete
1.INTRODUCTION Concrete is the most widely used material in the construction industry due to its strength, versatility, and adaptability. However, the production of cement, its key
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