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Abstract:

In this paper, the intluence of the flow distance on fibre distribution and orientation is investigated using two types of steel fibre reinforced self-compacting concrete (SFRSCC) (medium and high viscosity, but with similar flowability or slumpflow value). Beam elements are cast from one side, allowing the concrete to flow freely along the length of the 2 metre long mould. After curing, standardised prisms of 150×150×600mm3 are cut from these beams. These prisms are tested under three-point bending load, according to EN 14651, to determine the post-cracking behaviour in function of the flow length. Additionally, the spatial distribution and orientation of the fibres are measured by means of manual counting and image analysis. The results are also compared to a 30 representation obtained from X-ray computed tomography. The results seem to indicate that, independent from the viscosity of the mixture, preferential libre orientation is induced by shear flow of the concrete. As a consequence of this preferential orientation, fibre efficiency in bending is improved resulting in deflection hardening behaviour with only 0.38 volume% of steel fibres.