Abstract:This experimental study examines the combined effects of micro silica (silica fume, SF) as a partial cement replacement and hooked-end steel fibers on the mechanical properties of M40 grade concrete. Concrete mixes were designed as per IS:10262 with a target characteristic compressive strength of 40 MPa. Silica fume was incorporated at 0%, 5%, 10%, and 12% by weight of cement, while steel fibers (aspect ratio ~50) were added at volume fractions of 0%, 0.5%, 1.0%, and 1.5%. The objective of this study was to investigate the influence of these materials on the strength characteristics and overall performance of concrete, as well as to identify the optimum combination capable of producing a high-performance concrete mix suitable for structural applications. The use of silica fume and steel fibers has gained significant attention in recent years due to their ability to improve the mechanical and durability properties of conventional concrete. Tests were performed on fresh properties (slump) and hardened properties including compressive strength (cubes), splitting tensile strength (cylinders), and flexural strength (beams) at 7 and 28 days. The experimental program involved systematic evaluation and comparison of all concrete mixtures to assess the individual and combined contributions of silica fume and steel fibers. Results demonstrate significant enhancements: 12% SF replacement increased 7-day compressive strength by up to 45% and 28-day strength by approximately 40% compared to control mixes due to pozzolanic reactions, improved particle packing, and matrix densification. The incorporation of silica fume contributed to the refinement of the concrete microstructure, reducing pore spaces and enhancing the bond between cement paste and aggregates. Steel fibers provided notable improvements in tensile (up to 25–40%) and flexural strengths, along with enhanced toughness, ductility, crack resistance, and post-cracking behavior. The fibers acted as crack arrestors, bridging microcracks and delaying crack propagation under applied loads, thereby improving the overall structural performance of concrete. Hybrid mixes (e.g., 10–12% SF + 1–1.5% fibers) yielded optimal performance, transforming standard M40 concrete into a more durable, high-performance material. The combined use of silica fume and steel fibers resulted in a synergistic effect that enhanced both strength and deformation characteristics. Based on the experimental findings, the study confirms that the incorporation of micro silica and hooked-end steel fibers is an effective approach for developing concrete with superior mechanical properties, making it suitable for applications requiring increased strength, durability, and long-term service performance.

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1. Singh G, Singh M, Singh H. Study on collective effect of silica fume and steel fiber on strength and durability properties of concrete. Mater Today Proc. 2021;37(Pt 2):2256–2265. doi: 1016 /j.matpr.2020.07.701.
2. Köksal F, Altun F, Yiğit İ, Şahin Y. Combined effect of silica fume and steel fiber on the mechanical properties of high strength concretes. Constr Build Mater. 2008;22(8):1874–1880.
3. Durmaz M. Synergistic effects of steel fibers and silica fume on concrete exposed to high temperatures and gamma radiation. Buildings. 2025;15(11):1830. doi: 3390/buildings15111830.
4. Nili M, Afroughsabet V. The effects of silica fume and steel fibers on the impact resistance and mechanical properties of concrete. Constr Build Mater. 2010;24(6):927–933.
5. Biolzi L, Cattaneo S. Response of steel fiber reinforced high strength concrete beams: Experiments and code predictions. Cem Concr Compos. 2017;77:1–13. doi: 1016/j.cemconcomp.2016.12.002.
6. Eid R, Paultre P. Compressive behavior of FRP-confined reinforced concrete columns. Eng Struct. 2017;132:518–530. doi: 1016/j.engstruct.2016.11.052.
7. Li JJ, Wan CJ, Wu YC. Investigation on flexural toughness evaluation method of steel fiber reinforced lightweight aggregate concrete. Mater Struct. 2009;42(5):607–617.
8. Caratelli A, Imperatore S, Meda A, Rinaldi Z. Punching shear behaviour of lightweight fiber reinforced concrete slabs. Eng Struct. 2011;33(6):1843–1852.
9. Pogorelov SN, Semenyak GS. Frost resistance of steel fiber reinforced concrete containing active mineral additives. Mag Civ Eng. 2014;48(4):45–53.
10. Grabois TM, Cordeiro GC, Filho RDT. Fresh and hardened-state properties of self-compacting lightweight concrete reinforced with steel fibers. Constr Build Mater. 2016;104:284–291.
11. Dundar C, Tokgoz S, Tanrikulu AK. Studies on carbon fiber polymer confined slender plain and steel fiber reinforced concrete columns. Eng Struct. 2008;30(10):2849–2857.
12. Kim J, Lee GP, Moon DY. Evaluation of mechanical properties of steel fibre reinforced concrete exposed to high temperatures by double punch test. Constr Build Mater. 2015;79:182–191.
13. Karadelis JN. Flexural strengths and fibre efficiency of steel fibre reinforced roller compacted polymer modified concrete. Constr Build Mater. 2008;22(3):452–459.
14. Xie T, Ozbakkaloglu T. Behavior of steel fiber reinforced high strength concrete filled FRP tube columns under axial compression. Eng Struct. 2015;90:121–132.
15. Patil S. Study of flexural strength in steel fibre reinforced concrete. Int J Eng Res Technol. 2015;4(7):451–455.
16. Harle S. Steel fibre reinforced concrete and its properties. Int J Civ Struct Eng Res. 2014;2(1):8–12.
17. Vishnuram BG. Studies on steel fibre reinforced concrete: A sustainable approach. Int J Sci Eng Res. 2015;6(5):1020–1025.
18. Choi SY, Won JP, Kim YY. A study on the shrinkage control of fiber reinforced concrete pavement. Constr Build Mater. 2007;21(9):1865–1872.
19. Gadge NA, Jadhav HS. Mix design of fiber reinforced concrete using slag and steel fiber. Int J Innov Res Sci Eng Technol. 2014;3(6):13456–13463.
20. Shende AM, Pande AM, Gulfam P. Experimental study on steel fiber reinforced concrete for M40 grade. Int Ref J Eng Sci. 2012;1(1):43–48.
21. Köksal F, Altun F, Yiğit İ, Şahin Y. Combined effects of silica fume and steel fibers on high-strength concrete. Constr Build Mater. 2008;22(8):1874–1880.
22. Durmaz M. Synergistic effects of steel fibers and silica fume on concrete exposed to high temperatures and gamma radiation. Buildings. 2025;15(11):1830. doi: 3390/buildings15111830.
23. Kumar R, Sharma A. Experimental investigation on M40 concrete with silica fume and steel fiber hybridization. Int J Creat Res Thoughts. 2023;11(4):d321–d329.
24. Enhancing performance of M35/M40 concrete using silica fume and steel fibers. Int J Creat Res Thoughts. 2024;12(2):f112–f120.
25. Jagan S, Kumar PS, Rajesh R. Effect of silica fume on hardened and durability properties of M40 concrete. Mater Today Proc. 2021;46:7890–7896.

Abstract:This experimental study examines the combined effects of micro silica (silica fume, SF) as a partial cement replacement and hooked-end steel fibers on the mechanical properties of M40 grade concrete. Concrete mixes were designed as per IS:10262 with a target characteristic compressive strength of 40 MPa. Silica fume was incorporated at 0%, 5%, 10%, and 12% by weight of cement, while steel fibers (aspect ratio ~50) were added at volume fractions of 0%, 0.5%, 1.0%, and 1.5%. The objective of this study was to investigate the influence of these materials on the strength characteristics and overall performance of concrete, as well as to identify the optimum combination capable of producing a high-performance concrete mix suitable for structural applications. The use of silica fume and steel fibers has gained significant attention in recent years due to their ability to improve the mechanical and durability properties of conventional concrete. Tests were performed on fresh properties (slump) and hardened properties including compressive strength (cubes), splitting tensile strength (cylinders), and flexural strength (beams) at 7 and 28 days. The experimental program involved systematic evaluation and comparison of all concrete mixtures to assess the individual and combined contributions of silica fume and steel fibers. Results demonstrate significant enhancements: 12% SF replacement increased 7-day compressive strength by up to 45% and 28-day strength by approximately 40% compared to control mixes due to pozzolanic reactions, improved particle packing, and matrix densification. The incorporation of silica fume contributed to the refinement of the concrete microstructure, reducing pore spaces and enhancing the bond between cement paste and aggregates. Steel fibers provided notable improvements in tensile (up to 25–40%) and flexural strengths, along with enhanced toughness, ductility, crack resistance, and post-cracking behavior. The fibers acted as crack arrestors, bridging microcracks and delaying crack propagation under applied loads, thereby improving the overall structural performance of concrete. Hybrid mixes (e.g., 10–12% SF + 1–1.5% fibers) yielded optimal performance, transforming standard M40 concrete into a more durable, high-performance material. The combined use of silica fume and steel fibers resulted in a synergistic effect that enhanced both strength and deformation characteristics. Based on the experimental findings, the study confirms that the incorporation of micro silica and hooked-end steel fibers is an effective approach for developing concrete with superior mechanical properties, making it suitable for applications requiring increased strength, durability, and long-term service performance.

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.

1. Singh G, Singh M, Singh H. Study on collective effect of silica fume and steel fiber on strength and durability properties of concrete. Mater Today Proc. 2021;37(Pt 2):2256–2265. doi: 1016 /j.matpr.2020.07.701.
2. Köksal F, Altun F, Yiğit İ, Şahin Y. Combined effect of silica fume and steel fiber on the mechanical properties of high strength concretes. Constr Build Mater. 2008;22(8):1874–1880.
3. Durmaz M. Synergistic effects of steel fibers and silica fume on concrete exposed to high temperatures and gamma radiation. Buildings. 2025;15(11):1830. doi: 3390/buildings15111830.
4. Nili M, Afroughsabet V. The effects of silica fume and steel fibers on the impact resistance and mechanical properties of concrete. Constr Build Mater. 2010;24(6):927–933.
5. Biolzi L, Cattaneo S. Response of steel fiber reinforced high strength concrete beams: Experiments and code predictions. Cem Concr Compos. 2017;77:1–13. doi: 1016/j.cemconcomp.2016.12.002.
6. Eid R, Paultre P. Compressive behavior of FRP-confined reinforced concrete columns. Eng Struct. 2017;132:518–530. doi: 1016/j.engstruct.2016.11.052.
7. Li JJ, Wan CJ, Wu YC. Investigation on flexural toughness evaluation method of steel fiber reinforced lightweight aggregate concrete. Mater Struct. 2009;42(5):607–617.
8. Caratelli A, Imperatore S, Meda A, Rinaldi Z. Punching shear behaviour of lightweight fiber reinforced concrete slabs. Eng Struct. 2011;33(6):1843–1852.
9. Pogorelov SN, Semenyak GS. Frost resistance of steel fiber reinforced concrete containing active mineral additives. Mag Civ Eng. 2014;48(4):45–53.
10. Grabois TM, Cordeiro GC, Filho RDT. Fresh and hardened-state properties of self-compacting lightweight concrete reinforced with steel fibers. Constr Build Mater. 2016;104:284–291.
11. Dundar C, Tokgoz S, Tanrikulu AK. Studies on carbon fiber polymer confined slender plain and steel fiber reinforced concrete columns. Eng Struct. 2008;30(10):2849–2857.
12. Kim J, Lee GP, Moon DY. Evaluation of mechanical properties of steel fibre reinforced concrete exposed to high temperatures by double punch test. Constr Build Mater. 2015;79:182–191.
13. Karadelis JN. Flexural strengths and fibre efficiency of steel fibre reinforced roller compacted polymer modified concrete. Constr Build Mater. 2008;22(3):452–459.
14. Xie T, Ozbakkaloglu T. Behavior of steel fiber reinforced high strength concrete filled FRP tube columns under axial compression. Eng Struct. 2015;90:121–132.
15. Patil S. Study of flexural strength in steel fibre reinforced concrete. Int J Eng Res Technol. 2015;4(7):451–455.
16. Harle S. Steel fibre reinforced concrete and its properties. Int J Civ Struct Eng Res. 2014;2(1):8–12.
17. Vishnuram BG. Studies on steel fibre reinforced concrete: A sustainable approach. Int J Sci Eng Res. 2015;6(5):1020–1025.
18. Choi SY, Won JP, Kim YY. A study on the shrinkage control of fiber reinforced concrete pavement. Constr Build Mater. 2007;21(9):1865–1872.
19. Gadge NA, Jadhav HS. Mix design of fiber reinforced concrete using slag and steel fiber. Int J Innov Res Sci Eng Technol. 2014;3(6):13456–13463.
20. Shende AM, Pande AM, Gulfam P. Experimental study on steel fiber reinforced concrete for M40 grade. Int Ref J Eng Sci. 2012;1(1):43–48.
21. Köksal F, Altun F, Yiğit İ, Şahin Y. Combined effects of silica fume and steel fibers on high-strength concrete. Constr Build Mater. 2008;22(8):1874–1880.
22. Durmaz M. Synergistic effects of steel fibers and silica fume on concrete exposed to high temperatures and gamma radiation. Buildings. 2025;15(11):1830. doi: 3390/buildings15111830.
23. Kumar R, Sharma A. Experimental investigation on M40 concrete with silica fume and steel fiber hybridization. Int J Creat Res Thoughts. 2023;11(4):d321–d329.
24. Enhancing performance of M35/M40 concrete using silica fume and steel fibers. Int J Creat Res Thoughts. 2024;12(2):f112–f120.
25. Jagan S, Kumar PS, Rajesh R. Effect of silica fume on hardened and durability properties of M40 concrete. Mater Today Proc. 2021;46:7890–7896.