Comparison of Compressive Strength of Steel and Polypropylene Fibres at Different Percentage

Abstract

This study examines the compressive strength of M25 grade fibre-reinforced concrete containing steel and polypropylene fibres at fibre contents of 0%, 0.25%, 0.50%, 0.75% and 1.00% by volume. A control mix without fibres was used for comparison. Concrete specimens were cast, cured and tested to evaluate the influence of fibre type and dosage on compressive strength.The study identifies the optimum fibre content and demonstrates the potential of fibre reinforcement in improving the mechanical performance of concrete.

Introduction

Concrete is widely used in construction because of its strength, durability, and cost-effectiveness. However, conventional concrete is brittle and susceptible to cracking. Fibre-Reinforced Concrete (FRC) improves these limitations by incorporating fibres that enhance strength, toughness, durability, and crack resistance. Among the commonly used fibres, steel fibres increase compressive strength, toughness, and energy absorption, while polypropylene fibres improve crack control, ductility, and durability.

This study compares the compressive strength performance of M25 grade concrete reinforced with different percentages (0.25%, 0.50%, 0.75%, and 1%) of steel and polypropylene fibres. Previous research has shown that fibre reinforcement improves concrete performance, with steel fibres generally providing greater strength enhancement and polypropylene fibres contributing to better crack resistance. However, direct comparisons between these fibre types under identical conditions are limited.

The experimental methodology involved preparing M25 concrete mixes, adding varying percentages of steel and polypropylene fibres, casting cube specimens, and conducting workability and compressive strength tests at 7 and 28 days. Material tests confirmed suitable properties of cement and aggregates, while the concrete mix was designed with a water-cement ratio of 0.44.

Results showed that steel fibres significantly improved compressive strength, increasing the 28-day strength from 26.88 MPa (control mix) to 30.14 MPa at 1% fibre content, which was the optimum percentage tested. In contrast, polypropylene fibres produced smaller improvements, with 28-day strength reaching 28.31 MPa at 1% fibre content. Lower polypropylene fibre percentages (0.25% and 0.50%) slightly reduced strength compared to conventional concrete, indicating weaker bonding efficiency at lower dosages.

Overall, the study concludes that both fibre types can enhance concrete performance, but steel fibres are more effective in improving compressive strength. The optimum fibre content for both materials was found to be 1%, with steel fibre-reinforced concrete exhibiting the highest strength and best overall mechanical performance.

Conclusion

• Steel fibre concrete provides good improvement in compressive strength. Polypropylene fibre concrete gives least improvement, but still performs better than normal concrete. • Steel fibre concrete also performs well, offering good strength and ductility, making it suitable for structural applications where higher load resistance is required. • Polypropylene fibre concrete shows comparatively lower load carrying capacity, but it is highly effective in controlling cracks and improving durability, making it suitable for non-structural and durability-focused applications.

References

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Copyright

Copyright © 2026 Md Mehrab Ansari, Hemant Sood. 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.