The effect of magnetic field parameters on fibre orientation in high-performance fibre-reinforced concrete

Abstract

We aim at determining the value of minimal magnetic induction for magnetic orientation of fibres in cementitious composite in a given mixture and establish the effect of the magnetic field shape on the final mechanical properties. The magnetic orientation is a suitable method to ensure the required direction of steel ferromagnetic fibres in the composite. The strength of the magnetic field (magnetic induction) and rheology of the fresh mixture play a crucial role in the magnetic orientation. A special device generating alternating and direct magnetic fields with different magnetic inductions was built to determine the minimal magnetic induction for the given mixture. Moreover, the effects of using alternating magnetic field are explored. The used magnetic inductions are 60 mT, 80 mT, 100 mT and 120 mT. The nondestructive inductive measuring method is applied to confirm the orientation of fibres in the hardened composite. The effect of the shape of the magnetic field and magnetic induction on flexural strength is presented. Moreover, the effects of using the alternating or direct magnetic field on the microstructure are explored using a scanning electron microscope.