FROST DAMAGE MECHANISM OF HARDENED CEMENT PASTE ADDED SHRINKAGE REDUCING AGENT BY CRYOGENIC SUCTION OF WATER EFFECT

収縮低減剤を混和したセメント硬化体の低温吸水効果による凍害劣化機構

For the formation of ice and its melting in the microstructure, Gibbs free energy for ice are lower than that of pore liquid. This results in the movement of water from fine pore to large pore and air voids. This phenomenon is so-called cryogenic suction pump. For coexistence of shrinkage reducing agent (SRA) in pore water, the movement of water into ice in air void is promoted by osmotic pressure effect as well as cryogenic suction pump effect. The authors used two different types of SRAs：one in the traditional one（SRA-1）, the other in the newly developed one（SRA-2）. The later in adsorbed strongly on cement was compared with traditional SRA-1. The authors prepared three different specimens of hardened cement paste（HCP：without SRA（OPC）, with SRA-1, with SRA-2. Length changes of HCP specimens increased with an increase of freezing/thawing cycles, and depended on the types of paste：SRA-1＞SRA-2＞OPC. However, the megascopic observation of frost damage did not correspond to the order of length changes：SRA-2＞SRA-1＝OPC. For the most serious damaged specimen added SRA-2, the gel pore less than 4nm increased during freezing/thawing cycles, where capillary pore decreased. The osmotic pressure due to present of SRA in pore liquid emptied the large gel pore and shrinkaged it providing increase of small gel pore. On the other hand, capillary pore was destroyed during freezing/thawing cycles, and then the capillary pore decreased. From these results, strong adsorbed SRA improves the resistance against frost damage, which is almost the same on specimens without SRA.本論文は、収縮低減剤が混和されたセメント硬化体の凍結融解劣化機構を解明するため、ギブス自由エネルギーの差によって働く低温吸水ポンプ作用と未凍結水移動の駆動力の増大によって気泡に隣接する毛細管空隙が断裂するという仮説を立て、凍結融解時の細孔構造変化及び長さ変化測定によって検証を行ったものである。その結果、収縮低減剤を混和したセメント硬化体において未凍結水の移動による毛細管空隙の収縮と比較的早いサイクルでひび割れが内部まで伝播したことを確認し、前述した仮説の妥当性を裏付けるとともに、収縮低減剤の種類によっては凍結融解抵抗性を損なわないことが確認された。

• Record URL:
  • https://doi.org/10.14250/cement.67.237
• Summary URL:
  • http://scholar.google.com/scholar_lookup?title=FROST+DAMAGE+MECHANISM+OF+HARDENED+CEMENT+PASTE+ADDED+SHRINKAGE+REDUCING+AGENT+BY+CRYOGENIC+SUCTION+OF+WATER+EFFECT&author=H.+KURIYAMA&author=S.+GOTOH&author=T.+NAWA&publication_year=2013
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/09163182
• Authors:
  • KURIYAMA, Hiroki
  • GOTOH, Suguru
  • NAWA, Toyoharu
• Publication Date: 2013

Language

• English
• Japanese

Media Info

• Media Type: Web
• Features: References;
• Pagination: pp 237-243
• Serial:
  • Cement Science and Concrete Technology
  • Volume: 67
  • Issue Number: 1
  • Publisher: Japan Cement Association
  • ISSN: 0916-3182
  • EISSN: 2187-3313
  • Serial URL: https://www.jstage.jst.go.jp/browse/cement/-char/en
• Publication flags:

  Open Access (libre)

Subject/Index Terms

• TRT Terms: Cement paste; Concrete hardening; Cryogenics; Expansion; Frost damage; Shrinkage; Suction pumps; Water
• Uncontrolled Terms: Pore structure
• Subject Areas: Highways; Materials; Pavements; I30: Materials;

Filing Info

• Accession Number: 01561325
• Record Type: Publication
• Source Agency: Japan Science and Technology Agency (JST)
• Files: TRIS, JSTAGE
• Created Date: Apr 27 2015 9:48AM