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エポキシ樹脂塗装が後施工プレート定着型せん断補強鉄筋の先端定着性能に与える影響

府川 徹^＊１・福浦 尚之^＊１・岡本 晋^＊２・新藤 竹文^＊３

今回実施した後施工プレート定着型のエポキシ樹脂塗装鉄筋の引抜き試験結果と，過去に実施した無塗装鉄筋を用いた同様の試験結果とを比較して，先端定着性能について検討した。本稿の範囲では，引抜き試験後の先端定着部の観察，必要定着長の比較の結果から，後施工プレート定着型鉄筋の先端定着では，鉄筋のふしに対する支圧抵抗力よりも充てん材−コンクリート界面の付着力の影響が大きいと考えられる。細径鉄筋の試験では，必要定着長の算定方法やエポキシ塗膜厚などがその評価結果に影響を与えている可能性があるので，付着強度の低減率，製造方法および塗膜厚の管理などはエポ筋指針[改訂版] に準拠するなど，安全側に運用することが望ましい。

＊１ 技術センター 土木技術研究所 土木構工法研究室
＊２ 成和リニューアルワークス（株）
＊３ 技術センター 土木技術研究所

Effect of Epoxy-resin Coating on the End Anchorage Performance of a Shear Reinforcement with Anchor Plate during Post-construction Usage

Tohru FUKAWA^*1, Naoyuki FUKUURA^*1, Susumu OKAMOTO^*2 and Takefumi SHINDOH^*3

We carried out a pull-out test on an epoxy-resin coated shear reinforcement with an anchor plate to evaluate post-construction usage. First, we observed the bond surface of the end anchorage zone, and then tried to determine the end anchorage length that provided the necessary end anchorage performance. Observing the bond surface revealed that the boundary bond between concrete and grout seems to have a greater effect on the end anchorage performance than the bearing capacity of the concrete on the ribs of the rebar. This seems to indicate that the epoxy-resin coating has a smaller effect on the required end anchorage length. Comparing the length with and without the epoxy-resin coating, however, we were not able to determine whether or not the epoxy-resin coating increases the length. Therefore, we concluded that the effect of an epoxy-resin coating on a shear reinforcement with an anchor plate on post-construction usage will be similar to that of an epoxy-resin coating on rebars without anchor plates in terms of the reduction rate of the bond strength, the coating procedure, quality control, and so on. This conclusion is based on the spirit of “safety ?first” and the fact that, in post-construction usage, the efficiency of a shear reinforcement with an anchor plate depends on the end anchorage performance.