The Effect of Magnetic Field on Bond Strength between Reinforcing Steel Bar and Steel Fiber Reinforced Concrete by means of Pull-out Test

In this research, the effect of applying magnetic field directly to steel fiber reinforced concrete specimens containing 1.5% volume of steel fiber on bond strength between reinforcing steel bar and concrete was experimentally investigated using a direct pull-out test. For this purpose, magnetic field was applied externally to the fresh specimens by means of an electromagnetic instrument, capable of causing the flux density of 5000 Gauss. In this study, the pull-out specimens were tested with two different bar diameters: 14 and 20 mm. The study also investigated, mechanical properties of the specimens in the terms of compressive, splitting tensile and flexural strengths at an age of 28 days. In addition, the microstructure of the specimens was analyzed by the SEM images. The experimental results demonstrated that the pull-out failure occurred for all the specimens. Furthermore, the bond strength of the specimens increased by about 83 and 51% correspond to the #14 and #20 rebars, respectively. In addition, thoughness parameter of concrete exposed to magnetic field increased by 82 and 53% correspond to the #14 and #20 rebars, respectively. Applying magnetic field to fresh concrete caused an increase in its compressive strength more than 21%. Following this, splitting tensile and flexural strengths of concrete specimens were inhanced up to 9 and 13%, respectively. Magnetic field also has the ability to compact the microstructure of concrete.