Magnetic Alignment of Micro Steel Fibers Embedded in Self-Compacting Concrete

Abstract

Steel fiber reinforced cementitious composites (SFRCC) have emerged as one of the most efficient techniques to improve the flexural capacity and ductility performance of concrete. However, one of the most significant shortcomings is the randomness of steel fibers direction in the concrete matrix, which influences the extent of mechanical enhancement for a limited fiber content. An experimental approach to control the direction of steel fibers embedded in self-compacting concrete is presented in this study, which is based on generating a driving rotating force to overcome the viscous impeding forces acting onto the embedded fiber. The mechanical performance of micro steel fiber reinforced self-compacting concrete members was investigated. A uniform magnetic field of 9.8×10-3 Tesla generated by a cylindrical powered coil was capable of aligning micro steel fibers embedded in fresh self-compacting concrete along the desired direction. The testing program included seven beam specimens of size of 100 ×100 x 500 mm3. The micro steel fiber contents considered were 0.35%, 0.70%, and 1.05% by volume. Fiber volume fraction of 0.35% was the optimum dosage for magnetic alignment as it achieved the highest extents of mechanical enhancement. The concrete specimens reinforced with 0.35% of steel fiber content have exhibited enhancement rates of 5%, 28%, and 30% in four-point failure load, maximum mid-span deflection, and compressive strength, respectively. Based on the visual analysis of cross-sectional images, the highest orientation factor achieved was 0.91 when steel fiber dosage was 0.35%, whereas the random non-magnetized steel fiber reinforced beams achieved an orientation factor ranging from 0.30 to 0.50.