Study of the Vapour Phase Diffusivity in Hardened Cement Pastes Based on Water Adsorption Isotherms

吸着等温線に基づく硬化セメントペースト内部における水蒸気拡散特性に関する検討

The characteristics of moisture diffusivity, which change depending on the water content, were examined based on the water adsorption isotherms of hardened cement pastes optimized by the BSB model. The maximum value of moisture diffusivity occurs in the monolayer adsorption state, regardless of material age or water cement ratio, and it decreases as the amount of monolayer adsorption increases. The mechanism of moisture diffusivity in hardened cement pastes can be split into two factors. One addresses the interaction effects between the surface of specimens and moisture becoming the driving force of adsorption before the monolayer adsorption state is reached. The other addresses the geometrical effects related to the diffusion pathway in the adsorbed state beyond the monolayer adsorption state.BET吸着等温線を拡張したBSBモデルにより最適化された硬化セメントペーストに対する水蒸気吸着等温線のデータに基づき，含水量に応じて遷移する蒸気相水分の拡散特性を検討した。蒸気相水分の有効拡散係数比は材齢や水セメント比に関わらず単分子吸着状態において最大値を示し，その最大値は単分子吸着量の増加，すなわち比表面積の増加にともなって線形的に減少する傾向にあることが明らかとなった。硬化セメントペースト内部における蒸気相水分の拡散特性は，乾燥状態から単分子吸着状態に至る過程では吸着の駆動力である試料界面と吸着ガスの間に働く相互作用，また，単分子吸着状態以上の含水状態においては微細構造の幾何学的特性に基づく拡散経路に関する影響が支配的となる二つのメカニズムを有しているものと考察された。

• Record URL:
  • https://doi.org/10.3151/crt.23.91
• Summary URL:
  • http://scholar.google.com/scholar_lookup?title=Study+of+the+Vapour+Phase+Diffusivity+in+Hardened+Cement+Pastes+Based+on+Water+Adsorption+Isotherms&author=H.+Utsumi&publication_year=2012
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/13404733
• Authors:
  • Utsumi, Hideyuki
• Publication Date: 2012

Language

• English
• Japanese

Media Info

• Media Type: Digital/other
• Features: Figures; References;
• Pagination: pp 91-97
• Serial:
  • Concrete Research and Technology
  • Volume: 23
  • Issue Number: 2
  • Publisher: Japan Concrete Institute
  • ISSN: 1340-4733
  • EISSN: 2186-2745
  • Serial URL: https://www.jstage.jst.go.jp/browse/crt/-char/en
• Publication flags:

  Open Access (libre)

Subject/Index Terms

• TRT Terms: Adsorption; Cement; Cement paste; Diffusivity; Isotherms; Moisture content; Vapor phases
• Subject Areas: Highways; Materials; Pavements; I32: Concrete;

Filing Info

• Accession Number: 01515447
• Record Type: Publication
• Source Agency: Japan Science and Technology Agency (JST)
• Files: TRIS, JSTAGE
• Created Date: Feb 24 2014 8:42AM