An Analytical Study of Hybrid Fibre Reinforced Concrete

Abstract

The Concrete possesses high compressive strength but exhibits low tensile strength and brittle failure characteristics. Hybrid Fibre Reinforced Concrete (HFRC) offers an effective solution by combining two different fibres to enhance strength, ductility, and durability. This study investigates the mechanical and durability properties of M40 grade HFRC incorporating galvanized steel fibres and glass fibres in varying proportions. Six concrete mixes were prepared with a total fibre content of 3% by weight of cement. The combinations investigated were S0G0, S3G0, S2G1, S1.5G1.5, S1G2, and S0G3. Experimental investigations included compressive strength, flexural strength, ultrasonic pulse velocity (UPV), permeability, dynamic modulus of elasticity, and dynamic Poisson’s ratio. Results indicate that hybridization of steel and glass fibres significantly improves the mechanical performance and durability of concrete. The optimum performance was observed in the S2G1 and S1.5G1.5 mixes, which exhibited enhanced compressive strength, flexural strength, reduced permeability, and superior crack resistance. The study demonstrates the effectiveness of hybrid fibre systems for high-performance concrete applications.

Introduction

This study examined the performance of Hybrid Fiber Reinforced Concrete (HFRC) made by combining galvanized steel fibers (GSF) and glass fibers (GF) in M40 grade concrete. Hybrid fibers improve concrete properties by increasing compressive and flexural strength, reducing brittleness, controlling crack propagation, and enhancing ductility. Steel fibers primarily improve strength and toughness, while glass fibers act as crack arrestors and reduce brittleness.

A literature review showed that hybrid fiber systems generally perform better than single-fiber concrete by improving compressive, tensile, and flexural strength as well as durability. Previous studies reported optimum fiber contents between 0.5% and 1.0%, while excessive fiber addition can reduce workability and cause fiber clustering. However, limited research has focused on combining fibers with different mechanical properties, such as steel and glass fibers.

The objective of the study was to evaluate the effect of different steel-glass fiber combinations on the compressive and flexural strength of M40 concrete. Six concrete mixes were prepared with a total fiber content of 3% by weight of cement, varying the proportions of steel and glass fibers:

• S0G0 (0% steel, 0% glass – control mix)
• S3G0 (3% steel, 0% glass)
• S2G1 (2% steel, 1% glass)
• S1.5G1.5 (1.5% steel, 1.5% glass)
• S1G2 (1% steel, 2% glass)
• S0G3 (0% steel, 3% glass)

Tests conducted included workability, compressive strength, and flexural strength.

Key Findings

• The highest compressive strength was achieved by Sample III (2% steel + 1% glass fiber):
  • 31.75 MPa at 7 days
  • 48.32 MPa at 28 days
• The highest flexural strength was also obtained by Sample III, reaching 6.42 MPa, which represented an 18.91% increase compared to plain concrete.
• Increasing the proportion of glass fiber beyond the optimum level resulted in reduced compressive and flexural strength.
• A direct relationship was observed between compressive strength and flexural strength; mixes with higher compressive strength also exhibited higher flexural strength.

Conclusion

The outcomes of experimental results, the 28 days compressive strength of the sample III S2G1 with 2% steel fibre and 1% glass fibre content is found optimum. The compressive strength of S2G1 is found +5.23% greater than sample without fibre S0G0. Inclusion of 1% glass fibre also gives the good result but by increasing the glass fibre more than 1%, decreases the compressive strength and least compressive strength is found at the sample VI which contains maximum 3% glass fibre and 0% steel fibre. Only steel fibre alsogives good result in compression. The sample contains 3% steel fibre has +1.18% greater compressive strength than sample S0G0. In the case of flexural strength after 28 days, sample III S2G1 contains 2% steel fibre and 1% glass fiber has +25.88% greater flexural strength than sample S0G0. Two other samples, S3G0 & S1.5G1.5also shows the growth in flexural strength as compareto S0G0this increment is +15.5% & +15.88%respectively. But furtherincrement in percentageof glass fibrereducingthe flexural strength of concrete.

References

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Copyright

Copyright © 2026 Mohammed Osama, 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.