セメント系硬化体の空隙表面の電気的性質がイオン拡散性状に及ぼす影響  [in Japanese] EFFECTS OF ZETA POTENTIAL ON DIFFUSION OF CHLORIDE ION IN HARDENED CEMENTITIOUS MATERIALS  [in Japanese]

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Abstract

塩化物イオン拡散性状の定量評価に必要な塩化物イオン実効拡散係数を算出する方法として、拡散セル法と電気泳動法があるが、両者より得られる拡散係数は一致しないことが問題となっている。この原因として、空隙構造および空隙表面電位による影響が考えられる。そこで本研究では、空隙構造の影響については酸素拡散係数に基づき、空隙表面電位の影響については電気浸透法から求めた硬化体のゼータ電位に着目し検討を行った。その結果、電気泳動法による拡散係数は空隙構造による支配的影響を受けていることと、ゼータ電位と電気泳動法による拡散係数から拡散セル法による拡散係数の換算が可能であることを明らかにした。

It is important for durability evaluation of reinforced concrete structure to predict the ions transport in concrete quantitatively. For example, in order to evaluate the durability against salt attack, the model for predicting the diffusivity of chloride ions in the concrete is required. The effective diffusion coefficient of chloride ions is needed in the model.<br/>In general, the migration test and the diffusion cell test are performed to estimate the effective diffusion coefficient in Japan. However, the diffusion coefficients obtained from these tests are not the same. It is considered that the micro-structure and the electrical properties of the pore in hardened cementitious materials affect the effective diffusion coefficient. The authors focused on zeta potential as the approximate value of the pore surface potential.<br/>In this study, the effective diffusion coefficient of chloride ions obtained by the migration test was defined as D<sub>mig</sub>, and the effective diffusion coefficient obtained by the diffusion cell test was defined as D<sub>diff</sub>, and(1)the effective diffusion coefficient of chloride ions was measured in two ways:migration test and diffusion cell test,(2)the measurement of zeta potential was carried out by the electro-osmosis test.<br/>As the result, the values of D<sub>mig</sub> and D<sub>diff</sub> were not the same. It was confirmed from the experimental results that the micro-structure and the electrical properties of pore surface affected these diffusion coefficients. In particular the migration test was affected only by the influence of the micro-structure in hardened cementitious materials, the diffusion cell method was affected by both the electrical properties and void structure.<br/>Further, the ratio:D<sub>diff</sub>/D<sub>mig</sub> was defined as an evaluation index of electrical impact, compared with zeta potential of the hardened cementitious materials.<br/>It was confirmed that the diffusion coefficient obtained the diffusion cell method can be calculated by using the diffusion coefficient obtained by the migration test and zeta potential.

Journal

  • Cement Science and Concrete Technology

    Cement Science and Concrete Technology 67(1), 378-385, 2014

    Japan Cement Association

Codes

  • NII Article ID (NAID)
    130004745772
  • Text Lang
    JPN
  • ISSN
    0916-3182
  • Data Source
    J-STAGE 
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