Comparative Flexural and Tensile Behaviours of Ultra-High Performance Fibre Reinforced Concrete with Different Steel Fibres

This research work focuses on the optimization of tensile strength and ductility of ultra-high performance fibre reinforced concrete (UHPFRC) using low steel fibre content. A fine grain ultra-high performance concrete (UHPC) matrix with a compressive strength of 190 MPa was developed. Six different high strength steel fibres were employed to improve the ductility of the matrix. Four micro steel fibres were two types of smooth straight fibres and two types of crimped fibres while two indented macro steel fibres were hooked ends fibre and straight fibre. Pull-out tests were carried out to determine the average fibre-matrix bond strength. The flexural and tensile performances of UHPFRC with six different steel fibres were investigated. The enhancements in flexural/tensile strengths, deflection/strain capacities, energy absorption capacity were significantly depended on the fibre types and fibre factor (V_f*L_f/D_f). The experimental and estimated results indicate that the use of 1.5 vol.% of the most effective fibre with L_f/D_f of 20 mm/0.2 mm guarantees to achieve a strain-hardening UHPFRC with an ultimate tensile strength of higher than 10 MPa.