Effects of concrete flow on the distribution and orientation of fibers and flexural behavior of steel fiber-reinforced self-compacting concrete beams

Several parameters during the fabrication process cause segregation and poor orientation of the fibers in steel fiber-reinforced concrete (SFRC) members. With its high flowability and compactability, self-compacting fiber-reinforced concrete (SCFRC) can be used as an alternative to conventional SFRC, as it exhibits improved orientation and lesser fiber segregation. This study aims to investigate (1) the effects of concrete type (i.e., SCFRC versus SFRC), fiber content, and specimen depth on the fiber distribution and orientation and (2) the structural performance of SCFRC and SFRC beams considering their fiber distribution and orientation using X-ray images. The X-ray images showed that owing to the high-flow properties, the SCFRC beams exhibited a lower fiber segregation and better fiber alignment than the SFRC beams. The bending test results demonstrated that the SCFRC beams exhibited better flexural performance than the SFRC beams owing to the improved distribution and orientation of the fibers. Moreover, a finite element (FE) analysis was performed to evaluate the structural performance of the beams considering the varying fiber distribution properties observed in the X-ray images. The FE method could differentiate the superior structural performance of the SCFRC beam from that of the SFRC beam.