This experimental study examined the impact of recycled steel fibers (RSFs) from waste tires on the techanical behavior of normal concrete. The performance of recycled fibers and industrial steel fibers (ISFs) has been compared to examine recycled fibers’ impact more thoroughly. RSFs and ISFs with 0.5% and 1% volume percentages were used to strengthen the mixtures. The speci- mens were exposed to 200 �C, 400 �C, and 600 �C, and mechanical responses were determined after cooling. Mechanical properties were studied, including ultrasonic pulse velocity, compressive strength, splitting tensile strength, and flexural strength. The findings demonstrated that RSFs had no appreciable impact on the compressive strength of concrete at ambient temperature and 200 �C and even decreased it. At 400 �C and 600 �C, recycled fibers’ positive effect on concrete’s residual compressive strength was observed. Adding RSFs to concrete improved splitting tensile strength and modulus of rupture (MOR) at ambient and high temperatures. MOR increased with increasing fiber volume. The effect of fiber volume on toughness is significant at high temperatures. Overall, the mechanical and economic analysis showed that using RSFs is beneficial and economical for strengthening flexural members at ambient temperature and after exposure to high temperature.

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