Use of small beams to obtain design parameters of fibre reinforced concrete

In 2002, the final recommendation for the bending test of steel fibre reinforced concrete was presented by the RILEM TC162-TDF Committee. The test is performed on notched beams of 150 × 150 mm cross section with central point loading and makes possible to obtain representative parameters of the post-peak behaviour, such as the equivalent and the residual strengths. This paper analyses the possibilities of application of small beams for the characterization of FRC following the general guidelines of the mentioned recommendation. The use of smaller beams may simplify the test and can be particularly justified in FRC for low height structural elements, considering the effects of fibre orientation. Beams of different sizes cast with concretes incorporating different type and contents of steel fibres were tested using a closed-loop testing machine; both deflections and the crack mouth opening displacements were recorded. It was found that the post-peak parameters of FRC can be obtained using beams of smaller size when the fibre length and aggregate size are compatible with the dimension of the mould.