The Distribution, Structure, and Chemical Composition of Alkali-Silica Gels in Calcined Clay Concretes
This study investigates the effect of calcined clays (metakaolin, metasilt, metaclay) on the chemical composition, distribution, and structure of alkali–silica reaction (ASR) gels. Using 10 wt% of calcined clays reduced concrete expansion and minimized cracking but did not inhibit ASR gel formation....
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| Format: | Article |
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MDPI AG
2025-01-01
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| Series: | Buildings |
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| Online Access: | https://www.mdpi.com/2075-5309/15/2/218 |
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| author | Miriam E. Krüger Anne Heisig Stefanie Lode Klaartje de Weerdt Alisa Machner |
| author_facet | Miriam E. Krüger Anne Heisig Stefanie Lode Klaartje de Weerdt Alisa Machner |
| author_sort | Miriam E. Krüger |
| collection | DOAJ |
| description | This study investigates the effect of calcined clays (metakaolin, metasilt, metaclay) on the chemical composition, distribution, and structure of alkali–silica reaction (ASR) gels. Using 10 wt% of calcined clays reduced concrete expansion and minimized cracking but did not inhibit ASR gel formation. Micro X-ray fluorescence mapping revealed an average ASR gel content of 3 wt% in concrete, incorporating up to two-thirds of K<sub>2</sub>O and nearly all Na<sub>2</sub>O from the binder. Raman spectroscopy indicated structural similarities among gels in different concrete mixes, with an increased degree of polymerization in the metakaolin-containing concrete. Automated mineralogy identified four gel phases: Si gel, Ca-Si gel, Al-Ca-Si gel, and Al-Si gel. Ca-Si gels are formed at binder interfaces, while non-swellable Al-bearing gels are mainly formed in metakaolin-containing concrete located within aggregates. This study shows that aluminum can be incorporated into gels in calcined clay concretes, altering their structure and potentially affecting their expansion behavior in concrete. |
| format | Article |
| id | doaj-art-6fdbcd3d69d44cd3a92e29fc0924afd3 |
| institution | Kabale University |
| issn | 2075-5309 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Buildings |
| spelling | doaj-art-6fdbcd3d69d44cd3a92e29fc0924afd32025-01-24T13:26:13ZengMDPI AGBuildings2075-53092025-01-0115221810.3390/buildings15020218The Distribution, Structure, and Chemical Composition of Alkali-Silica Gels in Calcined Clay ConcretesMiriam E. Krüger0Anne Heisig1Stefanie Lode2Klaartje de Weerdt3Alisa Machner4Department of Materials Engineering, TUM School of Engineering and Design, Technical University of Munich, Lichtenbergstraße 2, 85748 Garching, GermanyDepartment of Materials Engineering, TUM School of Engineering and Design, Technical University of Munich, Lichtenbergstraße 2, 85748 Garching, GermanyDepartment of Geoscience and Petroleum, Norwegian University of Science and Technology, 7031 Trondheim, NorwayDepartment of Structural Engineering, Norwegian University of Science and Technology, 7034 Trondheim, NorwayDepartment of Materials Engineering, TUM School of Engineering and Design, Technical University of Munich, Lichtenbergstraße 2, 85748 Garching, GermanyThis study investigates the effect of calcined clays (metakaolin, metasilt, metaclay) on the chemical composition, distribution, and structure of alkali–silica reaction (ASR) gels. Using 10 wt% of calcined clays reduced concrete expansion and minimized cracking but did not inhibit ASR gel formation. Micro X-ray fluorescence mapping revealed an average ASR gel content of 3 wt% in concrete, incorporating up to two-thirds of K<sub>2</sub>O and nearly all Na<sub>2</sub>O from the binder. Raman spectroscopy indicated structural similarities among gels in different concrete mixes, with an increased degree of polymerization in the metakaolin-containing concrete. Automated mineralogy identified four gel phases: Si gel, Ca-Si gel, Al-Ca-Si gel, and Al-Si gel. Ca-Si gels are formed at binder interfaces, while non-swellable Al-bearing gels are mainly formed in metakaolin-containing concrete located within aggregates. This study shows that aluminum can be incorporated into gels in calcined clay concretes, altering their structure and potentially affecting their expansion behavior in concrete.https://www.mdpi.com/2075-5309/15/2/218Alkali-silica reaction (ASR)calcined claysalkali uptakescanning electron microscopy-automated mineralogy (SEM-AM)micro X-ray fluorescence (µ-XRF)microstructure |
| spellingShingle | Miriam E. Krüger Anne Heisig Stefanie Lode Klaartje de Weerdt Alisa Machner The Distribution, Structure, and Chemical Composition of Alkali-Silica Gels in Calcined Clay Concretes Buildings Alkali-silica reaction (ASR) calcined clays alkali uptake scanning electron microscopy-automated mineralogy (SEM-AM) micro X-ray fluorescence (µ-XRF) microstructure |
| title | The Distribution, Structure, and Chemical Composition of Alkali-Silica Gels in Calcined Clay Concretes |
| title_full | The Distribution, Structure, and Chemical Composition of Alkali-Silica Gels in Calcined Clay Concretes |
| title_fullStr | The Distribution, Structure, and Chemical Composition of Alkali-Silica Gels in Calcined Clay Concretes |
| title_full_unstemmed | The Distribution, Structure, and Chemical Composition of Alkali-Silica Gels in Calcined Clay Concretes |
| title_short | The Distribution, Structure, and Chemical Composition of Alkali-Silica Gels in Calcined Clay Concretes |
| title_sort | distribution structure and chemical composition of alkali silica gels in calcined clay concretes |
| topic | Alkali-silica reaction (ASR) calcined clays alkali uptake scanning electron microscopy-automated mineralogy (SEM-AM) micro X-ray fluorescence (µ-XRF) microstructure |
| url | https://www.mdpi.com/2075-5309/15/2/218 |
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