Applicability of magnetic field for directed orientation of steel fibres in high-performing cementitious composites

Abstract

This paper explores the practical possibility of using a magnetic field to orient steel fibres in a fresh concrete matrix. This process leads to preferential orientation, which increases the desired mechani- cal properties of the hardened material. In general, this paper focuses on the technical aspects of the orientation process and identifies key areas, such as the strength and shape of the magnetic field, velocity of the sample’s passage through the magnetic field and viscosity of the materials. A proto- type orienting apparatus was constructed with different permanent magnet systems to evaluate their performance. An ultrasound gel and a cementitious matrix were used as a medium for the fibres. Numerical simulations were created to further understand the effects of the magnetic field’s strength and shape. The final orientation of the fibres in hardened concrete was evaluated using Q factor measurements, X-ray scans and bending tests. A sufficiently strong magnetic field can be used to orient fibres in fresh concrete.