Two-Dimensional Magnetic Orientation of Steel Fibers in Slab Elements Made of High-Performance Fiber-Reinforced Concrete

Abstract This study investigated the feasibility and effects of two-dimensional magnetic orientation of steel fibers in high-performance fiber-reinforced concrete (HPFRC) slab elements subjected to punching loading. Although one-dimensional fiber orientation has shown significant improvements in concrete’s mechanical properties, this research explored fiber application in two-dimensional configurations. This could offer advantages in prefabricated construction, such as ceiling panels, traffic barriers, protective structures, and so forth. The scope of the work involved manufacturing HPFRC specimens with various two-dimensional fiber orientation patterns using a custom-built magnetic orientating device. A nondestructive method, utilizing a coil’s quality factor Q measurements, was employed to evaluate the success of fiber alignment. The mechanical performance was assessed using quasi-static punching tests with clamped circumference. Cracking patterns were analyzed to understand failure mechanisms, which clearly revealed the oriented fiber paths. Two-dimensional fiber orientation was achieved successfully, proving that the manufacturing process works well. However, the results indicate that despite this, preferential alignment does not universally enhance punching resistance in all loading scenarios. In fact, semirandom fiber orientation performed comparably to some orientation patterns and significantly better than others, suggesting that specific loading cases, such as punching, benefit from the more-homogeneous properties of randomly distributed fibers. This study proposes possible future research headings to optimize the orientation process and usage.