Impact of nanoparticles and steel fibers on the mechanical properties of concrete beams: an experimental study

Abstract

This study examines the combined effects of nanoparticles (SiO₂ and Al₂O₃) and steel fibers on the mechanical and flexural performance of concrete beams with binder contents of 350 and 550 kg/m³. Eight mixtures were tested following IS and RILEM standards. Nanoparticles showed minimal influence on density but affected strength and deformation. SiO₂ increased compressive strength by 16% in the 350 series, while Al₂O₃ improved flexural strength by about 4%. In the 550 series, only slight gains in strength and stiffness were observed, with maximum loads between 233–240 kN and moments of 78.7–81.0 kN·m. Steel fibers (0.5%) enhanced ductility, raising maximum deflection to 31.5 mm compared to 9–14 mm in non-fibered beams. Stiffness ratios (EIII, theo/EIII, exp) ranged from 0.78–1.70, confirming model reliability. Overall, Al₂O₃ improved stiffness, SiO₂ enhanced ductility, and fibers increased post-cracking resistance, demonstrating the potential of combined nanomaterial-fiber reinforcement for improving concrete performance.