Improvement of Flexural Performance of UHPFRC with Hybrid Steel Fiber

This study investigates the flexural behavior of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) with hybrid steel fiber referencing the ASTM standard C 1609. Two types of end-hooked fibers in macro fiber concretes and one type short straight fiber in micro fiber concretes were used in mono and hybrid forms. In order to determine the flexural response of UHPFRC, a series of prismatic beam specimens with a dimension of 100 x 100 x 400 mm were tested under the four-point loading and following parameters were compared and discussed in terms of the first cracking load and pattern, flexural strength, deflection capacity, toughness and residual strength capacity under bending loads. The test results showed that as the fiber amount of specimens with the mono fiber increases, in general, better flexural behavior may be ensured. It should be also noted that the hybrid use enhanced the flexural behavior compared to the macro fiber usage