INFLUENCE OF ALKALI ON DIFFUSION OF CLORIDE IONS INTO HARDENED CEMENT

セメント硬化体中の塩化物イオンの拡散におけるアルカリイオン濃度の影響

Chloride induced steel corrosion is the greatest problem for the durability of reinforced concrete structures exposed to marine environment. Chloride induced steel corrosion is fundamentally occurs due to diffusion of chloride ion into concrete, which is greatly affected by the alkali ions in the pores. But the prediction model of diffusion of chloride ion is not still established. Therefore, experiments were carried out using specimens with different alkali contents. It was confirmed experimentally that the alkali ions strongly influenced the diffusion of chloride ion, and then enhanced the authors' previous model integrated with phase equilibrium model , surface complex model and multi-component diffusion model, considering that when alkali ion concentration increased in the pore, Si in C-S-H was replaced by Al. The Al substitution changed adsorption and also varied the equilibrium constant in surface complexation reaction. Refined model with modified equilibrium constant in surface complexation reaction could predict preciously the experimental data. Therefore diffusion was influenced by Al substitution. It is necessary to accurately predict the diffusion in consideration of Al ion substituted.塩化物イオン拡散メカニズムの解明はセメント内塩分浸透抑制を行う上で重要である。塩化物イオンの拡散過程において、細孔中のアルカリイオンによって大きく影響を及ぼすが定量的な結論は明らかにされていない。そこで細孔中のアルカリイオン濃度の異なる供試体を用いたセメント硬化体中の塩化物イオンの拡散予測と実験結果から検証を行った。しかし、相平衡モデル、表面錯体モデル、多種イオン拡散モデルを用いた拡散予測結果ではアルカリイオン濃度の変化により実験結果と大きく乖離を生じた。そこで、アルカリイオンと密接な関係にあるSi₄がAl₃に置換する反応をモデルに組み込み、モデルの構築を行った。

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  • Accession Number: 01562532
  • Record Type: Publication
  • Source Agency: Japan Science and Technology Agency (JST)
  • Files: TRIS, JSTAGE
  • Created Date: Apr 23 2015 10:50AM