Optimizing aligned steel fiber distribution in UHPC: Unraveling the electromagnetic influence of steel reinforcements

The performance of ultra-high performance concrete (UHPC) can be improved by the magnetic orientation of steel fibers. The reinforcement frame has strong interference with the magnetic field, and this interference may even make the production of oriented steel fibers fail. However, the study of the electromagnetic interference caused by fixed steel reinforcements has not been undertaken. In this paper, the steel fiber distributions under the interference of steel bars were tested, and the impact of different steel reinforcement diameters, lengths, and magnetic flux densities on the magnetic field was studied. The results reveal that stirrups minimally impact the magnetic field, whereas longitudinal reinforcement exerts a substantial influence. Therefore, it is feasible to manufacture an aligned steel fiber UHPC reinforced structure with a steel framework, and only the influence of longitudinal reinforcements needs to be considered. An analytical model based on electromagnetic theory was employed to elucidate the influence of longitudinal reinforcement and analyze the distribution of magnetic lines. Numerical analysis shows that the influenced range of the magnetic lines exhibited a logarithmic relationship with the flux density and a linear relationship with the length and diameter of the reinforcement. Therefore, when accompanied by a judiciously selected magnetic flux density, longer and thinner steel reinforcements are found to be conducive to achieving a comprehensive orientation of steel fibers. •Employing electromagnetic technology for the fabrication of aligned steel fiber UHPC.•The influence of steel bars on the electromagnetic interference affecting fiber orientation was investigated.•Deriving the analytical equation for magnetic field distribution under the interference steel bars, based on electromagnetic theory.•Evaluating the effects of magnetic field strength, steel bar diameter, and length on fiber orientation.