Evaluation of the mass transfer properties of concrete by hydration product in consideration of the environmental effects of Okinawa

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14709
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Civil engineering materials/Construction/Construction management
• Research Institution: University of the Ryukyus
• Principal Investigator: Suda Yuya 琉球大学, 工学部, 助教 (10636195)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: C-S-H / 乾燥 / 炭酸化 / 微細構造 / 拡散係数 / 相対湿度 / 重合度 / Ca/Si比

Outline of Final Research Achievements

The environmental effect in Okinawa on mass transport of concrete was investigated. In addition, the purpose of this study is to clarify the different of the environmental effect between areas. As a result, the diffusion coefficient of chloride ion and oxygen gas increased with the decreasing the relative humidity at the arbitrary drying condition . In order to evaluate the effect between areas on diffusion coefficient of ion, hardened cement samples were exposed at Okinawa and Niigata. The diffusion coefficient of sample changed during the proceeding of exposure period. Results indicated that the property of mass transport is influenced by the drying and carbonation during the exposure period. In the fundamental study, cement paste samples were exposed to accelerated carbonation under 3% carbon dioxide concentration at different RH conditions. It is clarified that the change of the mass transport is affected by the structural change with the change of chemical composition of C-S-H.

Free Research Field

コンクリート工学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果より，暴露後のコンクリートの性能が乾湿繰返しや炭酸化などの影響によって，長期的に変化していくことが明らかとなり，特に，炭酸化による影響が大きいことが明確となった．さらに，炭酸化時の湿度の違いによって，炭酸化する水和物が異なることが示され，C-S-Hについては，ポルトランダイトと比較して中程度の湿度で炭酸化が進行しやすいことを示した．これにより，本研究成果は，環境作用も含めた適切な劣化診断技術の確立と適材適所の材料利用を促すことが可能となる基礎資料として位置づけられ，沖縄県だけでなく東南アジアや大洋州などにも本成果の応用が期待できる．