Anisotropic behavior in the flexural properties of aligned steel fiber UHPC produced by electromagnetic field

Improving fiber utilization efficiency emerges as a viable strategy for bolstering the flexural strength of Ultra-High Performance Concrete (UHPC). However, scant attention has been given to investigating the influence of aligned fibers on their anisotropic characteristics. The aligned steel fibers UHPC (ASF-UHPC) were fabricated using electromagnetic technology, and the fiber inclination angle was studied. The flexural behavior of ASF-UHPC was tested, and the anisotropic behavior of ASF-UHPC was revealed. The ASF-UHPC samples were divided into 3 cases. Utilizing 13 mm fibers at a volume fraction of 1.5 %, Case 1, Case 2, and Case 3 flexural strengths are approximately 2.44 times, 0.65 times, and 0.39 times that of traditional UHPC (Case 0), respectively. The significance of fiber volume fraction and length on flexural performance was highlighted through parameter analysis, demonstrating their critical role in material strength and post-peak performance. In addition, a predictive formula for ASF-UHPC flexural strength was proposed, offering valuable guidance for UHPC and structural design.