Optimization of Steel Fibre Content for Enhancing Strength, Toughness, and Durability of High-Performance M50 Concrete

Abstract

Concrete is one of the most widely used construction materials; however, its low tensile strength and susceptibility to cracking can affect the long-term performance of structures. The use of steel fibres in concrete is an effective method to improve its mechanical and durability properties. This study presents an experimental investigation on the strength and durability characteristics of M50 grade concrete incorporating steel fibres in different proportions. Steel fibres were added at varying percentages by volume of concrete, and the performance of the mixes was evaluated through a series of laboratory tests. Fresh concrete properties were assessed using the slump test, while hardened concrete properties were determined through compressive strength, split tensile strength, and flexural strength tests. Durability performance was evaluated using water absorption and chemical resistance tests. The experimental results indicated that the inclusion of steel fibres significantly enhanced the tensile and flexural strength of M50 concrete, while also providing moderate improvement in compressive strength. The fibres helped control crack propagation and improved the overall toughness of the concrete. Durability tests showed reduced water absorption and better resistance to aggressive environmental conditions compared to conventional concrete. Among the different fibre contents investigated, the optimum performance was achieved at approximately 1.5% steel fibre content. The study concludes that steel fibre-reinforced M50 concrete offers improved strength, crack resistance, and durability, making it suitable for high-performance structural applications such as pavements, industrial floors, bridges, and high-rise buildings.

Introduction

Concrete is widely used in construction due to its high compressive strength and durability, but it has weaknesses such as low tensile strength, brittleness, and susceptibility to cracking. To address these issues, steel fibres are added to produce Steel Fibre Reinforced Concrete (SFRC), which improves crack resistance, ductility, energy absorption, and overall structural performance. This is especially important for M50 grade high-strength concrete, which, despite its strength, is still prone to brittle failure under tensile stresses.

The study focuses on evaluating the effect of steel fibres on the strength and durability of M50 concrete. Previous research shows that steel fibres significantly improve compressive, tensile, and flexural strength, enhance durability by reducing permeability, and increase toughness and crack control. However, performance depends on fibre dosage, geometry, and mix design, with most studies suggesting an optimal range of 1.0%–1.5% fibre content.

The experimental program uses M50 concrete made with OPC 53 grade cement, river sand, coarse aggregate, superplasticizer, and hooked-end steel fibres. Five mixes (0% to 2% fibre content) are tested. Specimens are prepared, cured, and evaluated for workability, compressive strength, split tensile strength, flexural strength, water absorption, acid resistance, and sulphate resistance according to relevant standards.

Tests are conducted at different curing ages, and durability is assessed through exposure to chemical solutions and permeability measurements. Overall, the study aims to identify the optimum steel fibre content that enhances both strength and durability for high-performance concrete applications in modern infrastructure.

Conclusion

Based on the experimental investigation conducted on the strength and durability properties of M50 grade concrete incorporating steel fibres, the following conclusions can be drawn: 1) The incorporation of steel fibres significantly influenced the mechanical and durability characteristics of M50 concrete. The performance of concrete improved with increasing fibre content up to an optimum level. 2) The workability of fresh concrete decreased with the increase in steel fibre content. The slump value reduced from 95 mm for conventional concrete (SF0) to 65 mm for concrete containing 2.0% steel fibres (SF2.0) due to increased internal friction and fibre interlocking. 3) Compressive strength showed a gradual increase with the addition of steel fibres. The maximum 28-day compressive strength of 60.8 MPa was obtained for the SF1.5 mix, representing an improvement of approximately 16% over conventional concrete. 4) Split tensile strength improved considerably with fibre incorporation. The highest tensile strength of 5.92 MPa was achieved at 1.5% steel fibre content, corresponding to an increase of approximately 39% compared to the control mix. 5) Flexural strength exhibited significant enhancement due to the crack-bridging action of steel fibres. The maximum flexural strength of 7.68 MPa was recorded for the SF1.5 mix, which was about 37% higher than that of conventional concrete. 6) The addition of steel fibres improved the durability characteristics of concrete by reducing permeability and restricting crack propagation. Water absorption decreased from 4.20% for the control mix to 3.25% for the SF1.5 mix. 7) Acid resistance and sulphate resistance of concrete improved with the inclusion of steel fibres. Fibre-reinforced specimens exhibited lower weight loss and higher residual compressive strength after exposure to aggressive chemical environments. 8) The optimum performance was achieved at 1.5% steel fibre content, which provided the best balance between workability, strength enhancement, and durability performance. 9) The incorporation of steel fibres transformed the brittle behavior of conventional M50 concrete into a more ductile and crack-resistant material, thereby enhancing structural reliability and service life. 10) Based on the overall results, steel fibre reinforced M50 concrete with 1.5% fibre content is recommended for high-performance applications such as bridges, industrial floors, pavements, airport runways, tunnels, and high-rise structures where superior strength and durability are required.

References

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Copyright

Copyright © 2026 Mr. Rahul Patidar, Mr. Azharuddin. 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.