ELUCIDATION OF RAPID REDUCTION MECHANISM OF INITIAL WATER FLOW THROUGH A CRACK IN CONCRETE

コンクリート中のひび割れ通水量の初期急速抑制機構の解明

This paper elucidates the mechanism of water flow reduction through a concrete crack, normally regarded as self-healing phenomenon. The rapid water flow reduction in the initial stage is especially considered. Water pass tests are performed to investigate the variation in water flow amount. From the results of water pass tests with several curing age of concrete, the effect of unhydrated cement is excluded. Observation of crack inside of specimen after water pass test shows no blockage by self-healing products, such as CaCO₃. Then, visual observation of water flow inside the crack reveals air bubble blockage to be the main cause of water flow reduction. By water flow observation with de-aired process and water saturation, air bubbles are generated from inside pores of concrete plus water supplied to crack. By additional observation, it is seen that air bubble still exists in the crack after 28 days under water flowing condition. This fact reveals that the effect of air bubbles can remain in long-term water flow reduction. In spite of the presence of self-healing products at the bottom crack surface, specimens with eliminated air bubble still have same water flow as initial state. Consequently, air bubble effect is the main cause of water flow reduction, both in the short and long term range of water flow reduction.本論文では従来コンクリートの自己治癒現象と目されてきたひび割れ内の通水量の経時的な変化について、初期段階での急激な抑制に着目し、そのメカニズムを検討した。通水量の抑制に対し未水和セメント量による比較や内部ひび割れ幅の変化に基づく分析を行い自己治癒現象との関係を検証した。その上で可視化実験での観察によりひび割れ内への気泡の出現という新たなメカニズムを発見した。さらに気泡の生成要因や長期的な影響について検討し、通水後1日の急激な抑制に加え1か月程度の長期的な通水量抑制現象においても気泡の影響が大きいことを確認した。

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  • English
  • Japanese

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  • Accession Number: 01563223
  • Record Type: Publication
  • Source Agency: Japan Science and Technology Agency (JST)
  • Files: TRIS, JSTAGE
  • Created Date: Apr 23 2015 10:58AM