Effect of Fly Ash and Metakaolin on Properties and Microstructure of Magnesium Oxysulfate Cement
To improve the mechanical performance and lower the production cost of magnesium oxysulfate cement (MOSC), this article investigates the effects of single and compounded addition of metakaolin (MK) and/or fly ash (FA) on the setting time, mechanical strength, water resistance, hydration product, com...
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MDPI AG
2022-02-01
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| Series: | Materials |
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| Online Access: | https://www.mdpi.com/1996-1944/15/4/1334 |
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| author | Tong Liu Chunqing Li Li Li Wenqiang Fan Yudong Dong Huihui Liang Hongjian Yang |
| author_facet | Tong Liu Chunqing Li Li Li Wenqiang Fan Yudong Dong Huihui Liang Hongjian Yang |
| author_sort | Tong Liu |
| collection | DOAJ |
| description | To improve the mechanical performance and lower the production cost of magnesium oxysulfate cement (MOSC), this article investigates the effects of single and compounded addition of metakaolin (MK) and/or fly ash (FA) on the setting time, mechanical strength, water resistance, hydration product, composition, and microstructure of the resulting cement. MOSC samples with different proportions, ranging from 0 to 30 wt.%, of FA and/or MK substituting magnesium oxide (MgO) were prepared. The microstructure was explored by scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. The findings suggest that adding FA can delay the setting of MOSC; however, the effect of adding MK to MOSC was reversed. Furthermore, the phase composition of the MOSC hydration products was unaltered upon adding FA and/or MK, but thicker and longer 517 phase crystals were observed. FA and MK can effectively fill the large pores of MOSC through filling and nucleation effects, reduce the pore size, and form a denser microstructure, thereby improving its mechanical properties. The optimal MOSC sample was found by substituting 10 wt.% of both FA and MK, resulting in a cement that exhibited a short setting time and an incredibly high mechanical strength and density. These findings will further the development of stronger, more cost-efficient, and more water-resistant MOSC products. |
| first_indexed | 2024-03-09T21:32:33Z |
| format | Article |
| id | doaj.art-8203b7986746415b96c44d37f66063a4 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-09T21:32:33Z |
| publishDate | 2022-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-8203b7986746415b96c44d37f66063a42023-11-23T20:51:47ZengMDPI AGMaterials1996-19442022-02-01154133410.3390/ma15041334Effect of Fly Ash and Metakaolin on Properties and Microstructure of Magnesium Oxysulfate CementTong Liu0Chunqing Li1Li Li2Wenqiang Fan3Yudong Dong4Huihui Liang5Hongjian Yang6School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, ChinaTianjin Cheng An Thermal Power Co., Ltd., Tianjin 300161, ChinaTianjin Cheng An Thermal Power Co., Ltd., Tianjin 300161, ChinaTianjin Cheng An Thermal Power Co., Ltd., Tianjin 300161, ChinaSchool of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, ChinaSchool of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, ChinaSchool of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, ChinaTo improve the mechanical performance and lower the production cost of magnesium oxysulfate cement (MOSC), this article investigates the effects of single and compounded addition of metakaolin (MK) and/or fly ash (FA) on the setting time, mechanical strength, water resistance, hydration product, composition, and microstructure of the resulting cement. MOSC samples with different proportions, ranging from 0 to 30 wt.%, of FA and/or MK substituting magnesium oxide (MgO) were prepared. The microstructure was explored by scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. The findings suggest that adding FA can delay the setting of MOSC; however, the effect of adding MK to MOSC was reversed. Furthermore, the phase composition of the MOSC hydration products was unaltered upon adding FA and/or MK, but thicker and longer 517 phase crystals were observed. FA and MK can effectively fill the large pores of MOSC through filling and nucleation effects, reduce the pore size, and form a denser microstructure, thereby improving its mechanical properties. The optimal MOSC sample was found by substituting 10 wt.% of both FA and MK, resulting in a cement that exhibited a short setting time and an incredibly high mechanical strength and density. These findings will further the development of stronger, more cost-efficient, and more water-resistant MOSC products.https://www.mdpi.com/1996-1944/15/4/1334MOSCmetakaolinmechanical propertieswater resistancemicrostructure |
| spellingShingle | Tong Liu Chunqing Li Li Li Wenqiang Fan Yudong Dong Huihui Liang Hongjian Yang Effect of Fly Ash and Metakaolin on Properties and Microstructure of Magnesium Oxysulfate Cement Materials MOSC metakaolin mechanical properties water resistance microstructure |
| title | Effect of Fly Ash and Metakaolin on Properties and Microstructure of Magnesium Oxysulfate Cement |
| title_full | Effect of Fly Ash and Metakaolin on Properties and Microstructure of Magnesium Oxysulfate Cement |
| title_fullStr | Effect of Fly Ash and Metakaolin on Properties and Microstructure of Magnesium Oxysulfate Cement |
| title_full_unstemmed | Effect of Fly Ash and Metakaolin on Properties and Microstructure of Magnesium Oxysulfate Cement |
| title_short | Effect of Fly Ash and Metakaolin on Properties and Microstructure of Magnesium Oxysulfate Cement |
| title_sort | effect of fly ash and metakaolin on properties and microstructure of magnesium oxysulfate cement |
| topic | MOSC metakaolin mechanical properties water resistance microstructure |
| url | https://www.mdpi.com/1996-1944/15/4/1334 |
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