PSI - Issue 82

Asad Zia et al. / Procedia Structural Integrity 82 (2026) 234–238

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A. Zia, I. Holly/ Structural Integrity Procedia 00 (2026) 000–000

dosage. At a hybrid fiber content of 0.70%, the tensile strength surpassed that of the mix reinforced solely with industrial hook-end steel fibers (0.5HIF). However, at the same dosage level of 0.50%, the hybrid mix (0.5CTF) demonstrated approximately 17% lower tensile strength compared to 0.5HIF, indicating the superior bridging effect of hook-end fibers at lower fiber volumes. Nevertheless, the higher hybrid fiber content (0.70%) resulted in a 4% increase in tensile strength relative to 0.5HIF, highlighting the potential of hybridization in enhancing post-cracking behavior. These results suggest that an optimized hybrid fiber dosage can effectively improve tensile performance, offering a promising alternative to conventional single-fiber reinforcement systems.

Fig. 4. Tensile strength results

4. Conclusions This study examined the performance (599 days) of hybrid fiber-reinforced concrete (HIFRC) incorporating tire derived steel fibers (TDFs) and industrial hook-end fibers (IHFs). The results indicate that: • The hybrid mix (0.7CTF) showed the lowest water absorption (7%), about 5.6% lower than the industrial fiber mix (0.5HIF), confirming improved resistance to water ingress. • The same hybrid mix exhibited the lowest carbonation-induced weight gain (2.56%), around 15% less than 0.5HIF, suggesting enhanced carbonation resistance. • At a higher hybrid dosage (0.70%), the tensile strength exceeded that of 0.5IHF by 4%, highlighting the potential of hybridization to improve long-term tensile performance. Overall, the optimized combination of TDFs and IHFs enhances both durability and tensile behavior, supporting the sustainable reuse of waste tires in structural concrete. Further research is recommended to examine the microstructural and durability aspects of hybrid fiber-reinforced concrete, including chloride penetration, freeze–thaw resistance, and corrosion performance, as well as its influence on reinforced concrete members. Acknowledgements The authors gratefully acknowledge the support of the Scientific Grant Agency of the Slovak Republic (VEGA) under project No. VEGA1/0358/23, the Interreg CENTRAL EUROPE Programme 2021–2027 (Project CE0100390 – ReBuilt), and the Slovak research and development agency research projects APVV-23-0193 and APVV-23-0383. References Alabdulkarim, A., El-Sayed, A.K., Alsaif, A.S., Fares, G., Alhozaimy, A.M., 2024. Behavior of Lightweight Self-Compacting Concrete with Recycled Tire Steel Fibers. Buildings 14, 2463. https://doi.org/10.3390/buildings14082463 Awolusi, T.F., Oke, O.L., Atoyebi, O.D., Akinkurolere, O.O., Sojobi, A.O., 2021. Waste tires steel fiber in concrete: a review. Innovative Infrastructure Solutions. https://doi.org/10.1007/s41062-020-00393-w Balea, A., Fuente, E., Monte, M.C., Blanco, A., Negro, C., 2021. Recycled fibers for sustainable hybrid fiber cement based material: A review.