Experimental analysis and numerical simulation of flow behavior of fresh steel fibre reinforced concrete in magnetic field

Fluidity is an important index to describe the performance of fresh concrete, which has a great influence on the transportation and casting process of concrete. By applying a magnetic field to steel fibre reinforced concrete, in which steel fibre can be oriented to improve flow performance and strength. In this paper, the mechanical model of steel fibre in magnetic field was established in EDEM, and the simulations of magnetic field orientation as well as slump of steel fibre concrete were carried out and compared with the experiment. The errors between numerical and experimental results are less than 5%, which confirms the validity of the model. The effects of magnetic flux density and duration on the orientation of steel fibre and the effect of orientation on flow of mortar were analyzed. It was found that the larger the magnetic flux density, the better orientation of steel fibre. And regardless of the magnitude of magnetic flux density, most steel fibres can be oriented in a relatively short time. Due to the effect of gravity, orientation of mortar in the bottom is more difficult than that in the upper. The magnetic flux density, the initial position of the steel fibre and the resistance to the steel fibre affect the final orientation. When the magnetic field direction is horizontal, the fluidity of mortar along the magnetic field direction decreases with the increase of magnetic flux density, while the fluidity along the vertical magnetic field direction increases. The vertical magnetic field has no obvious effect on the fluidity.