Development of Bond Test Method for Continuous Fiber Sheet

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In order to develop a test method for bond between continuous fiber sheet (CF Sheet) and concrete, it has been examined whether the bond properties of the sheet and concrete can be appropriately measured with use of a hexahedron block of concrete. Through the experimental work, it is found out that measurement of the strain distribution in a sheet by attached strain gages can show the bond stress distribution and peeling off with adequate accuracy during loading. In addition, the influences of the property of sheet (modulus of elasticity), properties of adhesion materials and concrete strength were evaluated quantitatively.Since the peeling off phenomenon can be defined as bond failure, concrete strength must affect the phenomenon. The test results, however, showed that the relationships between bond stress and relative displacement were almost identical while concrete strength was varied from 24 to 60 kN/mmィイD12ィエD1. It was considered that the surface properties of concrete were hardly changed in the range of above concrete strength. This was true for either case of carbon fiber and aramid fiber. However, the modulus of elasticity of adhesion resin affected greatly on the bond behavior. When the low modulus of elasticity of resin is used, the stress transfer length becomes longer and may result in fiber fracture instead of peeling off.Based on the bond stress - relative displacement relationships, it was developed how to determined the proper amount of continuous fiber sheet for strengthening the shear capacity of ordinary RC beams. The effectiveness of the proposed method was examined by comparison with test results.Through the research work it is concluded that the proposed test method for the bond of continuous fiber sheet and concrete can show sufficient as a standard test method.