Accelerated and natural carbonation of concrete with high volumes of fly ash: chemical, mineralogical and microstructural effects
Today, a rather poor carbonation resistance is being reported for high-volume fly ash (HVFA) binder systems. This conclusion is usually drawn from accelerated carbonation experiments conducted at CO2 levels that highly exceed the natural atmospheric CO2 concentration of 0.03–0.04%. However, such acc...
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| Format: | Article |
| Language: | English |
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The Royal Society
2019-01-01
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| Series: | Royal Society Open Science |
| Subjects: | |
| Online Access: | https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.181665 |
| _version_ | 1818480554613407744 |
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| author | Philip Van den Heede Mieke De Schepper Nele De Belie |
| author_facet | Philip Van den Heede Mieke De Schepper Nele De Belie |
| author_sort | Philip Van den Heede |
| collection | DOAJ |
| description | Today, a rather poor carbonation resistance is being reported for high-volume fly ash (HVFA) binder systems. This conclusion is usually drawn from accelerated carbonation experiments conducted at CO2 levels that highly exceed the natural atmospheric CO2 concentration of 0.03–0.04%. However, such accelerated test conditions may change the chemistry of the carbonation reaction (and the resulting amount of CH and C–S–H carbonation), the nature of the mineralogical phases formed (stable calcite versus metastable vaterite, aragonite) and the resulting porosity and pore size distribution of the microstructure after carbonation. In this paper, these phenomena were studied on HVFA and fly ash + silica fume (FA + SF) pastes after exposure to 0.03–0.04%, 1% and 10% CO2 using thermogravimetric analysis, quantitative X-ray diffraction and mercury intrusion porosimetry. It was found that none of these techniques unambiguously revealed the reason for significantly underestimating carbonation rates at 1% CO2 from colorimetric carbonation test results obtained after exposure to 10% CO2 that were implemented in a conversion formula that solely accounts for the differences in CO2 concentration. Possibly, excess water production due to carbonation at too high CO2 levels with a pore blocking effect and a diminished solubility for CO2 plays an important role in this. |
| first_indexed | 2024-12-10T11:25:14Z |
| format | Article |
| id | doaj.art-d31189958e1f4c7c918575199c18591e |
| institution | Directory Open Access Journal |
| issn | 2054-5703 |
| language | English |
| last_indexed | 2024-12-10T11:25:14Z |
| publishDate | 2019-01-01 |
| publisher | The Royal Society |
| record_format | Article |
| series | Royal Society Open Science |
| spelling | doaj.art-d31189958e1f4c7c918575199c18591e2022-12-22T01:50:47ZengThe Royal SocietyRoyal Society Open Science2054-57032019-01-016110.1098/rsos.181665181665Accelerated and natural carbonation of concrete with high volumes of fly ash: chemical, mineralogical and microstructural effectsPhilip Van den HeedeMieke De SchepperNele De BelieToday, a rather poor carbonation resistance is being reported for high-volume fly ash (HVFA) binder systems. This conclusion is usually drawn from accelerated carbonation experiments conducted at CO2 levels that highly exceed the natural atmospheric CO2 concentration of 0.03–0.04%. However, such accelerated test conditions may change the chemistry of the carbonation reaction (and the resulting amount of CH and C–S–H carbonation), the nature of the mineralogical phases formed (stable calcite versus metastable vaterite, aragonite) and the resulting porosity and pore size distribution of the microstructure after carbonation. In this paper, these phenomena were studied on HVFA and fly ash + silica fume (FA + SF) pastes after exposure to 0.03–0.04%, 1% and 10% CO2 using thermogravimetric analysis, quantitative X-ray diffraction and mercury intrusion porosimetry. It was found that none of these techniques unambiguously revealed the reason for significantly underestimating carbonation rates at 1% CO2 from colorimetric carbonation test results obtained after exposure to 10% CO2 that were implemented in a conversion formula that solely accounts for the differences in CO2 concentration. Possibly, excess water production due to carbonation at too high CO2 levels with a pore blocking effect and a diminished solubility for CO2 plays an important role in this.https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.181665carbonationhigh-volume fly ashsilica fumethermogravimetric analysisx-ray diffractionmercury intrusion porosimetry |
| spellingShingle | Philip Van den Heede Mieke De Schepper Nele De Belie Accelerated and natural carbonation of concrete with high volumes of fly ash: chemical, mineralogical and microstructural effects Royal Society Open Science carbonation high-volume fly ash silica fume thermogravimetric analysis x-ray diffraction mercury intrusion porosimetry |
| title | Accelerated and natural carbonation of concrete with high volumes of fly ash: chemical, mineralogical and microstructural effects |
| title_full | Accelerated and natural carbonation of concrete with high volumes of fly ash: chemical, mineralogical and microstructural effects |
| title_fullStr | Accelerated and natural carbonation of concrete with high volumes of fly ash: chemical, mineralogical and microstructural effects |
| title_full_unstemmed | Accelerated and natural carbonation of concrete with high volumes of fly ash: chemical, mineralogical and microstructural effects |
| title_short | Accelerated and natural carbonation of concrete with high volumes of fly ash: chemical, mineralogical and microstructural effects |
| title_sort | accelerated and natural carbonation of concrete with high volumes of fly ash chemical mineralogical and microstructural effects |
| topic | carbonation high-volume fly ash silica fume thermogravimetric analysis x-ray diffraction mercury intrusion porosimetry |
| url | https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.181665 |
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