Stress-strain Behavior of Steel-Polypropylene Hybrid Fiber Reinforced Concrete Under True Triaxial Compression

Abstract

Keywords: Hybrid fiber reinforced concrete; True triaxial compression; Stress-strain relation; Volumetric deformation. Abstract. This paper investigates the stress-strain behavior of steel-polypro pylene hybrid fiber reinforced concrete (HyFRC) under true triaxial compression. Three definitive lateral pressure combinations of 5/10MPa, 4/15MPa and 3/20MPa were performed for different fiber volume fractions and aspect ratios. Axial stress-strain relations and volumetric-axial strain relations were analyzed with respect to the variation of fiber reinforcement index. The test results showed that the steel fiber was observed to be a major contributor to the strength of HyFRC under true triaxial compression in that strength was dramatically improved with increases in both volume fraction and aspect ratio. The polypropylene fiber was found to have no significant impact on strength under all loading conditions, while the ductile performance was significantly improved by increasing the volume fraction of the polypropylene fiber. In addition, both the steel fiber and polypropylene fiber were observed positively improved the volumetric-axial strain curve, the steel fiber mainly contributed to the delaying of the onset of dilation while polypropylene fibers acted primarily to reduce the dilation rate. It is concluded that the behavior of HFRC is effectively the combined behavior of both steel fiber reinforced concrete and polypropylene fiber reinforced concrete, benefiting from the advantages of both steel fiber and polypropylene fiber and exhibiting a synergistic response in respect of strength, deformation capacity and post peak ductility.