2018 Fiscal Year Final Research Report
Effects of pre-drying and coexisting materials on expansion of cement hadrened body due to secondary ettringite formation
| Project/Area Number |
16K06438
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Civil engineering materials/Construction/Construction management
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| Research Institution | Niigata University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | 硫酸塩劣化 / エトリンガイト / 二次生成 / モノサルフェート / C-S-H / C-A-S-H / 27Al NMR / Al配位数 |
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| Outline of Final Research Achievements |
The present study experimentally examined the effects of monosulfate pre-drying conditions and coexisting materials on secondary ettringite formation. Synthesized monosulfate samples dried under varying conditions and with coexisting materials such as C-S-H were mixed with a sodium sulfate solution, and the amount of secondary ettringite was found to increase following drying under 0% or 11% relative humidity. The secondary ettringite proportion was also markedly increased by the presence of C-S-H, regardless of the pre-drying conditions, and calcium-aluminate-silicate-hydrates (C-A-S-H) containing four-coordinate Al were formed in these samples. It is evident that ettringite is likely to form from four-coordinate Al, and that C-S-H promotes secondary ettringite formation because it transitions six-coordinate Al derived from the monosulfate to four-coordinate Al by substituting Al in the Si chains.
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| Free Research Field |
土木材料、セメント・コンクリート化学
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| Academic Significance and Societal Importance of the Research Achievements |
遅延EttやC-S-Hに含まれる水の存在形態およびその構成比について着目し，未だ実証されていないFamyらによる「仮説」を，単純化した「実験」によって，共存物質であるC-S-Hの影響を「定量的」に「把握・実証」しようとする試みは世界初であり，また乾燥条件の制御やC-S-Hの影響を「定量的」に把握するために, 水蒸気吸着等温線の測定，コンダクションカロリメータによる測定および27Al-NMRによるEttの形状・構造解析等，これまで用いられてこなかった新しい分析技術を用いて「実証する」ことは学術的かつ独創的な点であると考えられる．
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