【公開日：2024.07.25】【最終更新日：2024.06.21】
課題データ / Project Data
課題番号 / Project Issue Number
23QS0020
利用課題名 / Title
Phase evolution, mechanical properties, and morphology of cementitious silicate hydrates subjected to carbonation
利用した実施機関 / Support Institute
量子科学技術研究開発機構 / QST
機関外・機関内の利用 / External or Internal Use
外部利用/External Use
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）物質・材料合成プロセス/Molecule & Material Synthesis
【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
セメント材料,局所構造,X線回折/ X-ray diffraction,放射光/ Synchrotron radiation
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)
Bae Sungchul
所属名 / Affiliation
Department of Architectural Engineering, Hanyang University
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
兼松 学,Sumin Im,Gyeongryul Kim,Seongmin Cho,Jin Yun,Junho Kim,細川 隆行,堀合 航太
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
町田 晃彦
利用形態 / Support Type
（主 / Main）共同研究/Joint Research（副 / Sub）-
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)
To reduce CO2 emissions, it is essential to applicate supplementary cementitious materials (SCMs), such as fly ash, granulated blast-furnace slag, and silica fume, that can partially replace cement. Despite the diversification in cement composition, the volume fraction of calcium–silicate–hydrate (C–S–H) still accounts for more than approximately 50% of the total composition of cement hydration products. Due to the abundance of elements capable of modifying the C–S–H structure in SCMs, such as aluminum and magnesium, there are various types of silicate hydrates in cementitious materials (Fig.1): aluminum-incorporated C–S–H (C–A–S–H), magnesium-incorporated C–S–H (M–C–S–H), and magnesium silicate hydrate (M–S–H), respectively. These silicate hydrates affect the mechanical properties of cement paste according to the ratios of constituent elements (i.e., Ca/Si, Al/Si, Mg/Si, and Ca/Mg) [1]. There are three distinct periods during C–S–H carbonation, including a dissolution period, a diffusion period, and a slowly ongoing reaction period. During C–S–H carbonation under atmospheric conditions, C–S–H gel transforms into an amorphous silica gel and various polymorphs of calcium carbonate, such as amorphous calcium carbonates, calcite, vaterite, and aragonite [3]. Due to the heterogeneous and amorphous characteristics of C–S–H gel, the carbonation kinetics of interatomic structure of C–S–H and the correlation between chemical decomposition and mechanical properties remain unknown [4]. Furthermore, the carbonation kinetics of other amorphous silicate hydrates in PC-based materials with SCMs, such as C–A–S–H and M–S–H, still remain unclear. Therefore, this study aims to investigate the carbonation kinetics of silicate hydrates and the relationship between interatomic structural changes and mechanical properties of amorphous silicate hydrates after the early stage of carbonation via in-situ loading synchrotron X-ray scattering experiments.
実験 / Experimental
準備した合成 C–S–H, M–C–S–H, M–S–H, and C–A–S–H pasteに圧縮負荷をかけながら（常温）XRD実験を行う。事前に準備した試験片は 持ち込み装置である小型引張圧縮試験機一式（AC 100 V）を用いて、予備実験の結果より最大15~18 MPaまで0.5～1 MPa間隔で圧縮応力を負荷した圧縮試験を行う予定とした。BL22XUのSi (111)二結晶分光器で単色化した70 keVのX線を使用する。検出器には回折計に搭載された大型デジタル２次元X線検出器を用い、入射ビームサイズは0.5 mm × 0.5 mmとした。試験片からの距離Lを304 mmおよび654 mmでそれぞれPDFおよびXRD解析用のデータを収集した。
結果と考察 / Results and Discussion
After 10 min of carbonation, the peaks of MgCO3 and CaCO3 were detected as shown in the total X-ray scattering patterns. Furthermore, the intensity of the hump within the Q ranging from 1.5 to 2 Å increased, indicating that the depolymerization behavior of silicate chains in M-C-S-H was more apparent than that of C-S-H pastes. The interatomic distance at 2.4 Å regarding the calcium layers slightly decreased while that of the M-C-S-H phases almost unchanged after 30 min of carbonation. The peak intensity of interatomic distance between Mg and O increased. The PDF peaks according to the interatomic distance of Ca-Si (3.6 Å) decreased while that of M-C-S-H phase increased. These results show that the structural transformation from chain-like structure to plate-like structure due to the Mg substitution can reduce the decalcification behavior of C-S-H under carbon storage conditions.
図・表・数式 / Figures, Tables and Equations
Pair distribution functions of (A) C-S-H pastes and (B) M-C-S-H pastes after carbonation curing time of 10, 20, and 30 min
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
Reference
[1] E. Bernard, H. Nguyen, Magnesium
silicate hydrate (M-S-H) stability under carbonation, Cem Concr Res 178 (2024)
107459. https://doi.org/10.1016/J.CEMCONRES.2024.107459.
[2] D. Bonen, M.D. Cohen, Magnesium sulfate
attack on Portland cement paste — II. Chemical and mineralogical analyses, Cem
Concr Res 22 (1992) 707–718. https://doi.org/10.1016/0008-8846(92)90023-O.
[3] J.L. García Calvo, A. Hidalgo, C.
Alonso, L. Fernández Luco, Development of low-pH cementitious materials for
HLRW repositories: Resistance against ground waters aggression, Cem Concr Res
40 (2010) 1290–1297. https://doi.org/10.1016/J.CEMCONRES.2009.11.008.
Acknowledgments
This study was supported
by the National Research Foundation of Korea grants funded by the Korean government
(MSIT) (Grant numbers NRF-2022R1A2C2010350).
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.
- Kim Gyeong Ryul, Cho Seong Min, Her Sung Wun, Yang Ji Hwan, Bae Sung Chul, "Assessment of High Temperature Resistance of Metakaolin-Based Geopolymer according to Si/Al Molar Ratios", Korea Concrete Institute 2023 Autumn Academic Conference (Jeju, Korea), 令和5年11月2日
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