Bending performance of recycled aggregate concrete beams with hybrid tire-derived steel fibers

: This study examines the structural and material performance of hybrid recycled tire steel fibers (HRTFs) in recycled aggregate concrete (RAC), focusing on both plain concrete and reinforced beam applications. A hybrid fiber mix comprising of tire-derived and hook-end industrial steel fibers, in proportions of 60 % and 40 %, was utilized; the dosage rate was 40 kg/m 3 . Material-level tests assessed strength, elasticity, crack behavior, and shrinkage up to 142 days. Results showed that while the compressive strength of recycled aggregate concrete dropped by 12 %, tensile strength, toughness, and shrinkage resistance improved. Notably, linear shrinkage was reduced by 20 % at 142 days, and crack energy absorption increased significantly. Reinforced concrete (RC) beams were tested in flexure; beams were also designed with 18 % and 36 % less steel reinforcement to evaluate the impact of the HRTF. Beams incorporating HRTF exhibited enhanced ductility, more stable post-cracking behavior, and improved crack control, achieving a 5 % increase in normalized load compared with the reference beams. These findings confirm the potential of HRTFs to enhance the performance of RAC in both structural and durability aspects, supporting their use as a sustainable reinforcement strategy. Further research on dosage optimization and field-scale validation is recommended.