Fracture behavior of hybrid fiber reinforced normal strength and high strength concrete: comparison with plain and steel fiber reinforced concrete

Abstract

The paper presents an experimental investigation on the fracture behavior of hybrid-fiber reinforced normal strength concrete (HFRC) and hybrid-fiber reinforced high strength concrete (HFRHSC). The hybrid fiber used in the study constitutes of 0.75% steel fiber and 0.25% polypropylene fiber, by volume of the concrete. A three-point bend test on a notched beam has been performed based on the recommendations of RILEM as well as literature. Fracture parameters like the fracture energy, stress intensity factor, energy release rate and characteristic length has been evaluated from the load-deflection and load-CMOD curves. These were compared with values for the plain and steel fiber reinforced concrete reported in literature for similar type of mixes. Result suggests that hybrid fiber improved the fracture performance in comparison to the steel fiber reinforcement in case of normal strength concrete. For higher strength concrete, replacing steel fiber by hybrid fibers caused marginal reduction in the fracture parameters. Compared to plain unreinforced concrete, the fracture behaviour irrespective of the strength improved by addition of the hybrid fibers.