Development of high performance self-compacting hybrid fiber reinforced concrete

In this thesis study, 24 SCC mixtures with high strength that exhibits deflection hardening under bending were designed and these mixtures were reinforced with single fiber and also binary, ternary and quaternary fiber hybridization. 4 different types (steel and synthetic), aspect ratio and size (macro and micro) of fibers were used to investigate the effect of fibers in designed self-comoacting concrete (SCC). With the aim of researching the influence of coarse aggregate content on design mixtures, 3 different Coarse Aggregate/Total Aggregate (CA/TA) ratio having the same maximum aggregate size were determined as parameter. Besides the fresh properties (unit weight, air content, slump-flow, J-ring slump flow, V funnel) of these designed SCC mixtures, the mechanical (compressive strength, elasticity modulus, splitting and flexural tensile strength) and durability (capillary water absorption, restrained shrinkage, freeze-thaw, water permeability) properties of the samples of mixtures were examined. Besides, in order to investigate the effect of fiber reinforced SCC on the bond of reinforcing bars, large-scale beams having lap-spliced reinforcing bars were tested. As a result, for all CA/TA ratio, the fresh properties of the SCC mixtures having binary fiber hybridization with OL 6/.16 micro steel fiber were determined to be the best while those of the mixtures having ternary and quaternary fiber hybridization with OL 13/.16 micro steel and PVA fiber were determined to be the worst. In the aspect of ultimate strength, in compressive strength, SCC mixtures having binary fiber hybridization with OL 6/.16 micro steel fiber, in splitting tensile strength, the mixtures having binary fiber hybridization with PVA fiber and in flexural strength, the mixtures having ternary fiber hybridization with OL 13/.16 micro steel and PVA fiber were the most prominent mixtures. It was found that against capillary water absorption and water permeability, the SCC mixtures having only macro steel fiber and binary fiber hybridization with micro steel fiber, against freeze-thaw cycles and restrained shrinkage, all mixtures with CA/TA in the ratio of 0.35 were the most durable mixtures. Besides, especially the bond strength of the beam specimens of the mixtures having ternary fiber hybridization with OL 13/.16 micro steel and PVA fiber were found to be the highest one.