Shear behaviour of concrete beams with recycled aggregate and steel fibres.

Highlights • Effect of steel fibres and recycled aggregate content on the shear behaviour of reinforced concrete beams. • Development of a mixing process considering the particular characteristics of RA. • The densified form of SF appears to exhibit a different behaviour compared to its original (dispersed) condition. • It is feasible to produce HPC without incorporating natural aggregates (NA). • Lack of appropriate formula to predict the behaviour of steel fibres recycled aggregate concrete beams. • Steel fibres can partially compensate the lack of transverse reinforcement in terms of shear behaviour. Abstract This paper mainly studies the shear characteristics of reinforced concrete beams manufactured by introducing coarse recycled aggregate (RA) and steel fibres. For that purpose, 27 concrete beams (15 cm, 20 cm and 150 cm of width, height and length, respectively) with dissimilar spacing of transverse reinforcement (TR) were produced. Additionally, the RA obtained from building demolition waste and introduced in the concrete mixes at 0%, 50% and 100%. Furthermore, the steel fibres (SF) were introduced in the beams at 0%, 1% and 2% to improve the flexural characteristics. Specimens underwent a 4 points bending test. In this test, the maximum deflection, shear capacity, at the mid-span of the beam and tension strain were obtained. The determination of the influence of SF and TR spacing and SF on RA reinforced concrete beams was the aim of this investigation. In addition, the results of this experiment and the requirements shown in the standards (e.g. CEB-fib model code, ACI and CSA) were compared. The results show that that SF improved the specimens' maximum strain and their use enhanced the shear behaviour of RA concrete beams relative to control specimens. [ABSTRACT FROM AUTHOR]