Analysis of the flexural properties of ultra-high-performance concrete consisting of hybrid straight steel fibers

Abstract

Three combinations of single fibers and nine combinations of hybrid fibers were tested to analyze the mechanical properties and crack propagation behavior of ultra-high-performance concrete (UHPC) by digital image correlation. It was found that in comparison to single fibers, the long fibers had a more pronounced effect than short fibers. The hybrid combination of medium length fiber (Vf = 0.5%) and long fiber (Vf = 1.5%) generated a better flexural behavior in terms of post-crack strength, deflection, toughness, than the other hybridization series. A digital image correlation (DIC) technique was applied to record the evolution of surface deformation. The hybrid use of longer fiber replaced the shorter fiber, long fiber replaced medium length fiber and short fiber, medium length fiber replaced short at lower replacement ratios (0.5% and 1.0%), the crack shapes were presented linear variation and showed an abrupt change and did not have a constant increment at higher replacement ratios (1.5% and 2.0%).