Characterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality construction
Abstract Metakaolin (MK) is one of the most sustainable cementitious construction materials, which is derived through a direct heating procedure known as calcination. Calcination process takes place substantially lower temperatures than that required for Portland cement, making it a more environment...
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Nature Portfolio
2023-11-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-023-46362-y |
| _version_ | 1797637003748048896 |
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| author | K. C. Onyelowe A. Naghizadeh F. I. Aneke D.-P. N. Kontoni M. E. Onyia M. Welman-Purchase A. M. Ebid E. I. Adah Liberty U. Stephen |
| author_facet | K. C. Onyelowe A. Naghizadeh F. I. Aneke D.-P. N. Kontoni M. E. Onyia M. Welman-Purchase A. M. Ebid E. I. Adah Liberty U. Stephen |
| author_sort | K. C. Onyelowe |
| collection | DOAJ |
| description | Abstract Metakaolin (MK) is one of the most sustainable cementitious construction materials, which is derived through a direct heating procedure known as calcination. Calcination process takes place substantially lower temperatures than that required for Portland cement, making it a more environmentally sustainable alternative to traditional cement. This procedure causes the removal of hydroxyl water from the naturally occurring kaolin clay (Al2Si2O5(OH)4 with MK (Al2O3·2SiO2) as its product. Kaolin naturally exists in large amount within 5°29′N–5°35′N and 7°21′E–7°3′E geographical coordinates surrounding Umuoke, Obowo, Nigeria. Alumina and silica are the predominant compounds in MK, which provide it with the pozzolanic ability, known as the 3-chemical pozzolanic potential (3CPP), with high potential as a cementitious material in concrete production and soil stabilization. Over the years, researchers have suggested the best temperature at which MK is derived to have the highest pozzolanic ability. Prominent among these temperature suggestions were 800 °C (3CPP of 94.45%) and 750 °C (3CPP of 94.76%) for 2 h and 5 h’ calcination periods, respectively. In this research paper, 11 different specimens of Kaolin clay obtained from Umuoke, Nigeria, were subjected to a calcination process at oven temperatures from 350 to 850 °C in an increment of 50 °C for 1 h each to derive 11 samples of MK. The MK samples and Kaolin were further subjected to X-ray fluorescence), scanning electron microscopy (SEM) and X-ray diffraction (XRD) Brunauer–Emmett–Teller (BET) tests to determine the microstructural behaviour and the pozzolanic properties via the 3CPP as to exploit the best MK with the highest cementing potential as a construction material. The results show that the MK heated at 550 °C and 800 °C produced the highest pozzolanic potentials of 96.26% and 96.28%, respectively. The enhancement in pozzolanic potential at optimum calcination temperature is attributed to an increase in the specific surface area upon calcination of kaolinite confirmed by BET results. The SEM and XRD results further supported the above result with the strengthened crystal structure of the MK at these preferred temperatures. Generally, 550 °C is more preferred due to the less heat energy needed for its formulation during 1 h of calcination, which outperforms the previous results, that suggested 750 °C and 800 °C in addition to longer hours of heat exposure. |
| first_indexed | 2024-03-11T12:42:08Z |
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| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-03-11T12:42:08Z |
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| spelling | doaj.art-cc28fca0f3ff4235835190e0926bba6b2023-11-05T12:15:17ZengNature PortfolioScientific Reports2045-23222023-11-0113111110.1038/s41598-023-46362-yCharacterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality constructionK. C. Onyelowe0A. Naghizadeh1F. I. Aneke2D.-P. N. Kontoni3M. E. Onyia4M. Welman-Purchase5A. M. Ebid6E. I. Adah7Liberty U. Stephen8Department of Civil Engineering, School of Engineering, University of the PeloponneseDepartment of Engineering Sciences, University of the Free StateSchool of Civil Engineering, University of KwaZulu-NatalDepartment of Civil Engineering, School of Engineering, University of the PeloponneseDepartment of Civil Engineering, Faculty of Engineering, University of NigeriaDepartment of Geology, University of the Free StateDepartment of Structural Engineering, Future University in EgyptDepartment of Civil and Environmental Engineering, University of CalabarDepartment of Civil Engineering, University of Agriculture and Environmental SciencesAbstract Metakaolin (MK) is one of the most sustainable cementitious construction materials, which is derived through a direct heating procedure known as calcination. Calcination process takes place substantially lower temperatures than that required for Portland cement, making it a more environmentally sustainable alternative to traditional cement. This procedure causes the removal of hydroxyl water from the naturally occurring kaolin clay (Al2Si2O5(OH)4 with MK (Al2O3·2SiO2) as its product. Kaolin naturally exists in large amount within 5°29′N–5°35′N and 7°21′E–7°3′E geographical coordinates surrounding Umuoke, Obowo, Nigeria. Alumina and silica are the predominant compounds in MK, which provide it with the pozzolanic ability, known as the 3-chemical pozzolanic potential (3CPP), with high potential as a cementitious material in concrete production and soil stabilization. Over the years, researchers have suggested the best temperature at which MK is derived to have the highest pozzolanic ability. Prominent among these temperature suggestions were 800 °C (3CPP of 94.45%) and 750 °C (3CPP of 94.76%) for 2 h and 5 h’ calcination periods, respectively. In this research paper, 11 different specimens of Kaolin clay obtained from Umuoke, Nigeria, were subjected to a calcination process at oven temperatures from 350 to 850 °C in an increment of 50 °C for 1 h each to derive 11 samples of MK. The MK samples and Kaolin were further subjected to X-ray fluorescence), scanning electron microscopy (SEM) and X-ray diffraction (XRD) Brunauer–Emmett–Teller (BET) tests to determine the microstructural behaviour and the pozzolanic properties via the 3CPP as to exploit the best MK with the highest cementing potential as a construction material. The results show that the MK heated at 550 °C and 800 °C produced the highest pozzolanic potentials of 96.26% and 96.28%, respectively. The enhancement in pozzolanic potential at optimum calcination temperature is attributed to an increase in the specific surface area upon calcination of kaolinite confirmed by BET results. The SEM and XRD results further supported the above result with the strengthened crystal structure of the MK at these preferred temperatures. Generally, 550 °C is more preferred due to the less heat energy needed for its formulation during 1 h of calcination, which outperforms the previous results, that suggested 750 °C and 800 °C in addition to longer hours of heat exposure.https://doi.org/10.1038/s41598-023-46362-y |
| spellingShingle | K. C. Onyelowe A. Naghizadeh F. I. Aneke D.-P. N. Kontoni M. E. Onyia M. Welman-Purchase A. M. Ebid E. I. Adah Liberty U. Stephen Characterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality construction Scientific Reports |
| title | Characterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality construction |
| title_full | Characterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality construction |
| title_fullStr | Characterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality construction |
| title_full_unstemmed | Characterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality construction |
| title_short | Characterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality construction |
| title_sort | characterization of net zero pozzolanic potential of thermally derived metakaolin samples for sustainable carbon neutrality construction |
| url | https://doi.org/10.1038/s41598-023-46362-y |
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