Mechanical properties of steel fibre concrete

Two types of hooked fibres and one type of twisted steel fibre were used as reinforcement in beam specimens of size 150 mm × 150 mm × 500 mm. A series of experiments was carried out to investigate the effect of size, shape and amount of steel fibres on the mechanical properties of concrete, such as the compressive strength, first-crack flexural strength and ultimate flexural strength, modulus of elasticity, flexural toughness and ductility. The guidelines of ASTM C1609 were used to carry out the bending tests. The compressive strengths of the concrete mixes were obtained from cylinder tests as per the guidelines of ASTM C39. The experimental findings indicate that addition of steel fibres in concrete can slightly enhance the compressive strength and modulus of elasticity, but remarkably improve flexural strength, flexural toughness and ductility. Results were further extended to find a simple formula for modulus of rupture (MOR) of steel fibre concrete, which is based on ACI 318 code formula for MOR of normal concrete.