Flexural and toughness properties of NiTi shape memory alloy, polypropylene and steel fibres in self-compacting concrete

Self-compacting concrete presents good workability to fill complicated forms without mechanical vibrations. This concrete is often reinforced with fibres to improve the strength and toughness. This study investigated the use of nickel -titanium (NiTi) shape memory alloy fibres in comparison with polypropylene and steel fibres in self-compacting concrete. The performances of the fresh fibre–reinforced self-compacting concrete are explored by slump flow and J-ring experiments. Meanwhile, the static and cyclic flexural tests are conducted to estimate the bending resistance strength performance, residual deformation and recovering capacity of shape memory alloy, polypropylene and steel fibre–reinforced self-compacting concrete. Moreover, the flexural toughness of the shape memory alloy, polypropylene and steel fibre–reinforced self-compacting concrete is calculated using four different codes. The shape memory alloy fibre–reinforced self-compacting concrete with 0.75% volume fraction presents the largest flexural strength, re-centering ability and toughness in comparison with polypropylene and steel fibre–reinforced self-compacting concretes. The experimental results demonstrated the beneficial influence of the shape memory and superelastic properties of NiTi in postponing initial crack formation and restricting the crack widths.