Addition of High Performance and Multi-Functions to Fiber Reinforced Concrete

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In this study, we intended to establish a determination method of tension softening diagrams of concrete and then discuss the fracture behavior of high performance fiber reinforced concrete which has a remarkable hardening region in bending.(1) Determination Method for Tension Softening DiagramsWe proposed a precise determination method of tension softening diagrams of concrete based on the poly-linear approximation method from experimental load-displacement curves.As a specimen displacement measured in loading tests, the crack opening displacement is superior than the loading point displacement, because the crack opening displacement is free from the settlement of the supporting points of specimens and can be easily measured.(2) High Performance Fiber Reinforced ConcreteIn addition to the high performance aramid fiber reinforced concrete with high flexural strength (20 MPa) and a remarkable hardening region, high performance fiber reinforced concrete having high amount of steel or vinylon fibers (up to 6% by volume) is developed and their properties are reported.In bending tests of concrete beam specimens, when the peak load is higher than the crack initiation load, plural cracks are observed on the beam side surfaces.The applicability of the tension softening diagrams based on the fictitious crack model to fiber reinforced concrete is investigated. In the case of steel fiber reinforced concrete, the fictitious model is applicable when the fiber content is less than 2 %, because the flexural fracture behavior is governed with a single crack. However, the model can not be applied for concrete with more than 4 % of steel fibers and therefore the properties can not be evaluated with the tension softening diagrams.