【公開日：2023.08.01】【最終更新日：2023.04.30】
課題データ / Project Data
課題番号 / Project Issue Number
22NU0409
利用課題名 / Title
Comparison of microstructure of ordinary Portland cement paste and low heat Portland cement paste
利用した実施機関 / Support Institute
名古屋大学
機関外・機関内の利用 / External or Internal Use
内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）物質・材料合成プロセス/Molecule & Material Synthesis（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）マテリアルの高度循環のための技術/Advanced materials recycling technologies（副 / Sub）-
キーワード / Keywords
電子顕微鏡/Electron microscopy
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
丸山 一平
所属名 / Affiliation
名古屋大学大学院環境学研究科
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）,技術補助/Technical Assistance
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
Drying induces shrinkage in concrete structures which may result in cracking, reducing the performance of structures. Drying phenomena and the induced drying shrinkage have been studied since several decades but in these studies, the drying rate is relatively quick comparing to that in thick concrete structures. With different rate of drying, we found that the drying shrinkage could be different depending on the cement paste composition. In this study, we aim to identify the possible reasons in the microstructure of cement pastes for such different shrinkage behavior.
実験 / Experimental
Ordinary Portland cement pastes and low-heat Portland cement pastes were used in this study. At the sample age of more than 91 days, hydration was stopped with isopropanol. Sample of size 5 mm was casted into epoxy and polished with SiC polishing paper after epoxy-hardening. Then, the polished surface was polished with Argon milling, under voltage of 14kV, during 14 hours. The smooth surface was osmium coated before observation under FE-SEM. Back scattered electron images were taken with magnification of 1000, voltage of 15kV, using the Field Emission Scanning Electron Microscope (JEOL, JSM-7500FA).
結果と考察 / Results and Discussion
From BSE images, it was observed that, compared to ordinary Portland cement paste, low heat Portland cement has more amorphous calcium silicate hydrates (C-S-H) which is the main phase shrinking due to drying. In addition, in low heat Portland cement less Portlandite (CH) crystals are incorporated in the amorphous C-S-H. The incorporated CH plays role of constraining the volume change of C-S-H. From this point, the C-S-H in low heat Portland cement paste is less restrained hence show higher shrinkage. Such observations are shown in the attached figures.
The above two points explaining the difference in shrinkage behavior are consistent with our shrinkage experiment, where it was found the drying shrinkage in low heat Portland cement is generally larger than ordinary Portland cement.
図・表・数式 / Figures, Tables and Equations
BSE image of ordinary Portland cement paste
BSE image of low heat Portland cement paste
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件