Effect of Steel Fibres on Flexural Toughness of Concrete and RC Beams

The study concerns the investigation of flexural behaviour of steel fibre reinforced concrete (SFRC) and conventional reinforce concrete (RC) beams incorporating steel fibre. Hooked-end steel fibres were used at the contents of 20 kg/m3, 40 kg/m3, 60 kg/m3, 80 kg/m3 and 100 kg/m3 in production of SFRC specimens and RC beams. Flexural tests were achieved on both SFRC and RC beams. Mechanical properties such as compressive strength, modulus of elasticity, flexural strength, toughness and toughness index were determined on SFRC specimens. Load–deflection curves were obtained from the beam flexural tests. First crack loads and flexural toughness of RC beams were also determined on RC beams. Steel fibres reduced the workability of fresh concretes. The mechanical performances of concretes and RC beams increased with the use of steel fibres. Compressive and flexural strengths of SFRCs have increased up to the 24.5% and 101.6% with increase in steel fibre, respectively. However, a decrease up to the 9.6% was observed in modulus of elasticity of SFRCs. Fibres have controlled the propagation and the widening of cracks. Therefore, considerable improvements were obtained on first crack loads, toughness and ductility of RC beams by addition of steel fibres. Maximum increases in first crack load and toughness of RC beams were 34.5% and 40.5%, respectively.