This paper investigates experimentally the influence of type, content and geometry of steel fibre (industrial/waste) on the mechanical properties of reactive powder concrete (RPC) in terms of compressive strength, tensile strength, modulus of elasticity and stress-strain behaviour under compression. Three types of steel fibres were used: industrial micro steel fibre (MF), industrial deformed steel fibre (DF) and waste steel fibre recovered from discarded tyres (WF). Steel fibres were added to RPC at 1%, 2%, 3% and 4% of the total volume. Two forms of steel fibres' hybridizations were explored: industrial hybridization (HF) and waste-industrial hybridization (WHF). Results of testing demonstrate that the addition of DF and WF up to 3% and 4%, respectively, significantly affected the flowability of RPC. The addition of 4% MF achieved the highest increase in the compressive strength, tensile strength, modulus of elasticity, peak stress and the corresponding strain. The inclusion of HF increased the RPC toughness by 245%. Moreover, the inclusion of the waste steel fibre as full replacement (WF) or partial replacement (WHF) was comparable to the industrial steel fibre in enhancing the mechanical properties of RPC in addition to the increase in the toughness of RPC by 158.8% and 211%, respectively. Finally, WF is considered as a promising material in the structural applications and can fully or partially replace industrial steel fibres in RPC.
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