X-Ray Computed Tomography Analysis of Magnetically Oriented Short Steel Fibers and their Effect on Uniaxial Tensile Strength of Cement Mortar

Abstract

The main objective of this study is to quantitatively determine the magnetic field capability of a Helmholtz coil in orienting steel fibers and show the correlation between the fiber orientation and tensile strength of steel fiber-reinforced concrete (SFRC) materials. Using X-ray computed tomography (CT), the exact distribution of fiber orientations was computed for both the magnetized and nonmagnetized samples containing 3, 5, 7, and 9 mm long fibers. The probability of a fiber being aligned parallel to the length of the specimen increased by 28.33%, 44.05%, 49.33%, and 27.12% for fibers with lengths of 3, 5, 7, and 9 mm, respectively. Finally, the uniaxial tensile strength of each sample was determined using direct tension tests. The average tensile strengths of the samples increased 0.51, 0.46, 0.64, and 0.76 MPa for the 3, 5, 7, and 9 mm fiber lengths, respectively. On average, the tensile strength of the samples increased by 27% after being exposed to an external magnetic field.