Hooked-end steel fibres boost concrete strength by up to 32.7% but slash workability

Adding hooked-end steel fibres to conventional concrete made with locally sourced Moroccan aggregates substantially increased compressive strength, but at a steep cost to workability, according to a new study published in Discover Materials on 24 October 2026. The research, led by Nour-eddine Ouslimane and colleagues, tested three fibre dosages of 20, 30, and 40 kg/m³ against a reference mixture with no fibres, using the Dreux–Gorisse mix design method to formulate the concrete.

Before any concrete was produced, the team characterised the locally sourced aggregates with standard physical and mechanical tests. A reference concrete mixture was then prepared as a baseline, and the three hooked-end steel fibre dosages were investigated against it. Workability, hardened density, and compressive strength were evaluated at 7 and 28 days, giving a controlled comparison across the dosage range.

The workability results showed a clear and progressive decline as fibre content rose. Slump fell from 6.0 cm for the control concrete to 1.5 cm at the highest dosage of 40 kg/m³, meaning the fibre-rich mixtures became markedly stiffer and harder to place. The authors note that this substantial reduction in workability is one of the key trade-offs identified by the study.

Hardened density moved in the opposite direction. Density increased with fibre content, reaching 2.53 g/cm³ at 28 days for the fibre-reinforced mixtures. Compressive strength also increased progressively with fibre dosage, and the effect was substantial at the highest addition rate.

At 28 days, compressive strength rose from 26.0 MPa for the control concrete to 34.5 MPa for the mixture containing 40 kg/m³ of fibres, a maximum increase of 32.7%. The measurements were made at both 7 and 28 days, allowing the strength development of each mixture to be tracked over the standard curing period.

The authors attribute the observed improvement plausibly to fibre bridging, stress transfer, and mechanical anchorage, the mechanisms by which hooked-end fibres are understood to restrain cracking and transfer loads across fissures in the cement matrix. However, they are careful to state that these mechanisms were not directly investigated in the present study, so the proposed explanation remains an interpretation rather than a demonstrated result.

The study is presented as providing a controlled reference dataset rather than a complete characterisation of fibre-reinforced concrete. The authors indicate that further investigation of tensile, flexural, post-cracking, and microstructural behaviour is needed to build on the dataset. Tensile and flexural performance, in particular, were not measured in this work, and the reported findings are limited to workability, hardened density, and compressive strength at two ages.

Within those limits, the results indicate that hooked-end steel fibres can improve the compressive performance of conventional concrete produced with locally sourced aggregates, while their incorporation substantially reduces workability. For practical mix design, the findings suggest that the choice of fibre dosage involves a direct trade-off between the strength gains documented at 28 days and the declining slump recorded as dosage increases from 20 to 40 kg/m³.

The article is published open access, and the version shared at publication is the accepted peer-reviewed manuscript, subject to further edits before the final Version of Record. The work was carried out by a team including Nour-eddine Ouslimane, Hanane Barebita, Youssef Merroun, Jaouad Bensalah, Fouad Dimane, and Mustapha Belfaquir, and was reported in Discover Materials, with the concrete produced entirely from locally sourced Moroccan aggregates characterised before production.

Subject of Research: Effects of hooked-end steel fibre dosage on the fresh and hardened properties of concrete designed with the Dreux–Gorisse method

Article Title: Influence of hooked-end steel fibres on the fresh and hardened properties of concrete using Dreux–Gorisse mix design method

Article References: Ouslimane, N.-E., Barebita, H., Merroun, Y., Bensalah, J., Dimane, F., & Belfaquir, M. (2026). Influence of hooked-end steel fibres on the fresh and hardened properties of concrete using Dreux–Gorisse mix design method. Discover Materials. https://doi.org/10.1007/s43939-026-01033-3

Image Credits: AI Generated

DOI: 10.1007/s43939-026-01033-3

Keywords: concrete, steel fibres, hooked-end fibres, compressive strength, workability, Dreux–Gorisse method, Moroccan aggregates, construction materials, density, fibre dosage, Influence, hooked-end