並列タイトル等ICCP-SS工法に用いる多機能型繊維補強セメント系複合材料(MFRCM)の付着挙動と劣化メカニズム
一般注記A sustainable repair method, which is called ICCP-SS (impressed current cathodic protectionand structural strengthening), has been proposed for deficient reinforced concrete structurescaused by corrosion of steel in concrete. In the implementation of the proposed method, amaterial that plays a dual functional role as structural reinforcement and impressed currentanode should be used and applied on concrete substrate. A multifunctional fabric reinforcedcementitious matrix (MFRCM) composite in which carbon fabric is incorporated is employedas such a functional material. While the MFRCM composite works in an ICCP-SS system theembedded carbon fabric is subjected to not only anodic polarization that is related toelectrochemistry but also the stress transferred from the surrounding matrix. Thus, there is aneed to investigate the bond behavior and degradation of carbon fabric embedded in the matrixunder anodic polarization, which helps gain an in-depth understanding of the global behaviorof MFRCM composites and the effectiveness and efficiency of the ICCP-SS method.Systematic research work was carried out, with a major aim at clarifying the bond behavior atthe interface between carbon fabric and cementitious matrix within MFRCM composites underanodic polarization. In the beginning, the bond behavior of carbon yarn embedded in a rangeof cementitious matrices was investigated. The bond slip relationship was determined for thecarbon yarn embedded in various matrices. The results show that the carbon yarns embeddedin various matrices feature a similar bond behavior that can be represented by a trilinear bondslip relationship. Once the tensile strength is attained, fracture of the embedded carbon yarn cantake place. An approach was derived to calculate the critical embedment length based on thebond slip relationship. Afterwards, the effect of matrix impregnation on the bond behaviorbetween carbon fabric and matrix was studied. The outer (impregnated) part and inner(unimpregnated) part can be distinguished within a single carbon yarn due to limited matriximpregnation. The percentage of the impregnated part was estimated as 30% of the wholecarbon yarn based on the image process and analysis results. Besides, the respective bond sliprelationship for the outer (matrix-outer part) and inner (outer part-inner part) interface wasdetermined based on the pullout test results. By carrying out finite element modeling thatincorporates the evaluated bond slip relationships, a good agreement can be achieved betweennumerical and experimental results. Besides, the stress transfer at the outer and inner interfacesand the contribution of the outer and inner parts to carrying the applied force as well as theeffects of key parameters on the pullout behavior were also discussed based on numericalsimulation.With introducing anodic polarization, MFRCM composites were investigated concerning theelectrochemical performance, the mechanisms of degradation and the bond behavior betweencarbon fabric and matrix. Stabilized electrochemical performance can be maintained forMFRCM composites polarized up to 125 mA/m2, while an exponential growth of cell voltagecan be seen for larger current densities. Using SEM, EDS, FTIR and XPS, the polarizationinduced changes in the chemical composition and morphology of carbon fabric and thesurrounding matrix were analyzed. The results reveal that the carbon fabric in the matrixshowed a clear sign of deterioration featured by multiple transverse cracks on the carbonfilaments and significant changes in the surface functional groups. The changes in themorphology of carbon fabric within MFRCM composites were also discussed. Finally, theeffect of anodic polarization on the bond behavior between carbon fabric and matrix wasexamined. The respective bond slip relationship for the outer and inner interface wasdetermined based on test results obtained from anodically polarized MFRCM composites. Theresults show that anodic polarization compromises the bond behavior for both interfaces,depending on the extent of anodic polarization. With increasing the extent of anodicpolarization, both the local bond strength and the residual bond stress decrease for the outerinterface, while the local bond strength is reduced for the inner interface.
(主査) 准教授 松本 浩嗣, 教授 松本 高志, 教授 杉山 隆文, 特任教授 横田 弘, 教授 上田 多門(深圳大学), 教授 Zhu Ji-Hua(深圳大学)
工学院（北方圏環境政策工学専攻）
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受理日（W3CDTF）2020-11-10T19:58:22+09:00
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