Abstract
Steel fibers are nowadays increasingly employed for improving the fracture behavior of concrete. However, the fiber alignment in fiber reinforced concrete (FRC) plays a significant role in its fracture behavior. This paper presents a method for aligning fibers in the desired direction, which is done by pouring concrete in the molds through a steel hopper, developed for this application. Both regular (without a notch) as well as notched beam specimens were cast using two steel fiber volume fractions of 0.8% and 1.2%. The beam specimens were tested in flexure under a central point load. The fracture parameters of FRC containing aligned steel fibers were compared with the FRC having randomly distributed fibers. The test results demonstrate the success of the method employed for aligning fibers. The FRC having 0.8% aligned steel fibers was almost as good as the FRC containing 50% more (i.e., 1.2%) random fibers. Mathematical analysis was carried out for the alignment of steel fibers achieved using the developed hopper and to predict the fiber orientation factor. The test results are in good agreement with the predicted values.