Investigation on Concrete Reinforced with Two Types of Hooked Fibers under Flexure

Steel fiber reinforced concrete (SFRC) is a material widely used for structural applications. The effectiveness of the steel fibers in the concrete matrix is strongly affected by the shape of the fibers. Because the steel fibers with various geometrical parameters are currently available, the knowledge about their influence on concrete response is needed. The paper presents the investigation on concrete reinforced with new type of fibers which are crimped along the length with additional hooks at the ends. To estimate the effect of this kind of fibers on the mechanical parameters of SFRC the typical hooked fibers were also investigated. The compressive and three-point flexural tensile tests were performed on specimens where three fiber contents were applied: 0.32%, 0.45% and 0.57%. The results indicate that the fracture energy did not differ apparently, whereas in the equivalent tensile strengths some differences were noted due to the change of fiber shape. The difference was only observed in the shape of the load-deflection curves obtained from the tests with a use of two fiber types. However, the compressive strength and flexural tensile strength at the limit of proportionality were more affected by crimped and hooked fibers than typical hooked ones. It shows that the new type of fiber may delay the formation of the cracks in the SFRC.