Influence of cement on properties of calcined phosphogypsum based composite cementitious materials
Phosphogypsum is an industrial waste generated in the production of fertilizers causing environmental problems. Calcined phosphogypsum (CPG) is obtained by low-temperature calcination and dehydration of phosphogypsum. CPG is mainly used to produce building materials. However, mechanical strength pro...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2023-05-01
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| Series: | Journal of Materials Research and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785423006580 |
| _version_ | 1797798832373760000 |
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| author | Fang Deng Jian Ye Yanling Liu Tianxiao Zhang Yishun Liao Shengwen Tang |
| author_facet | Fang Deng Jian Ye Yanling Liu Tianxiao Zhang Yishun Liao Shengwen Tang |
| author_sort | Fang Deng |
| collection | DOAJ |
| description | Phosphogypsum is an industrial waste generated in the production of fertilizers causing environmental problems. Calcined phosphogypsum (CPG) is obtained by low-temperature calcination and dehydration of phosphogypsum. CPG is mainly used to produce building materials. However, mechanical strength properties and water resistance of CPG materials is extremely poor, which leads to its relatively low utilization rate in construction industry. To address this issue, various amount of Ordinary Portland cement (OPC), fly ash (FA), rice husk (RH) and modified admixtures (AD) were mixed with the CPG to obtain CPG-based composite cementitious materials, which enhanced the water resistance and mechanical strength of the corresponding hardened materials. The influence of different contents of cement on the setting time, hydration heat, hydration products, mechanical properties, water absorption, heavy metal leaching and deterioration coefficient of the composite cementitious material is investigated. The results showed that the optimal mixing ratio of CPG: OPC: FA: RH was 57: 20: 10: 13 considering the water resistance and mechanical strength properties of CPG-based composite cementitious materials. On these conditions, the compressive strength, the flexural strength, water absorption and deterioration coefficient of the specimens at 28 days are 6.1 MPa, 4.6 MPa, 29.4% and 0.66 respectively, which were in line with the national standard of phosphorus building gypsum wallboard. It was demonstrated that two skeleton types are present in the samples prepared using CPG-based composite cementitious materials, which had a synergistic support effect on the structure. The first skeleton was formed by gypsum dihydrate crystals (CaSO4·2H2O) and provided strength to the specimens at an early stage, while the second skeleton was formed by ettringite (AFt) and C–S–H gels, which provided strength at a later stage. The skeletons make the hardened materials denser and more waterproof. Moreover, the composite materials exhibited a positive solidification effect on heavy metals present in CPG. |
| first_indexed | 2024-03-13T04:09:48Z |
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| institution | Directory Open Access Journal |
| issn | 2238-7854 |
| language | English |
| last_indexed | 2024-03-13T04:09:48Z |
| publishDate | 2023-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Materials Research and Technology |
| spelling | doaj.art-d9a0ce3fed4344dc9ff0261ac90f67a92023-06-21T06:56:14ZengElsevierJournal of Materials Research and Technology2238-78542023-05-012431453156Influence of cement on properties of calcined phosphogypsum based composite cementitious materialsFang Deng0Jian Ye1Yanling Liu2Tianxiao Zhang3Yishun Liao4Shengwen Tang5School of Environmental and Biological Engineering, Wuhan Technology and Business University, Wuhan, 430065, ChinaSchool of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, ChinaSchool of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, ChinaSchool of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, ChinaSchool of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, China; Hubei Provincial Engineering Research Center of Urban Regeneration, Wuhan, 430065, China; Institute of High Performance Engineering Structure, Wuhan University of Science and Technology, Wuhan, 430065, China; Corresponding author.State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, 430072, ChinaPhosphogypsum is an industrial waste generated in the production of fertilizers causing environmental problems. Calcined phosphogypsum (CPG) is obtained by low-temperature calcination and dehydration of phosphogypsum. CPG is mainly used to produce building materials. However, mechanical strength properties and water resistance of CPG materials is extremely poor, which leads to its relatively low utilization rate in construction industry. To address this issue, various amount of Ordinary Portland cement (OPC), fly ash (FA), rice husk (RH) and modified admixtures (AD) were mixed with the CPG to obtain CPG-based composite cementitious materials, which enhanced the water resistance and mechanical strength of the corresponding hardened materials. The influence of different contents of cement on the setting time, hydration heat, hydration products, mechanical properties, water absorption, heavy metal leaching and deterioration coefficient of the composite cementitious material is investigated. The results showed that the optimal mixing ratio of CPG: OPC: FA: RH was 57: 20: 10: 13 considering the water resistance and mechanical strength properties of CPG-based composite cementitious materials. On these conditions, the compressive strength, the flexural strength, water absorption and deterioration coefficient of the specimens at 28 days are 6.1 MPa, 4.6 MPa, 29.4% and 0.66 respectively, which were in line with the national standard of phosphorus building gypsum wallboard. It was demonstrated that two skeleton types are present in the samples prepared using CPG-based composite cementitious materials, which had a synergistic support effect on the structure. The first skeleton was formed by gypsum dihydrate crystals (CaSO4·2H2O) and provided strength to the specimens at an early stage, while the second skeleton was formed by ettringite (AFt) and C–S–H gels, which provided strength at a later stage. The skeletons make the hardened materials denser and more waterproof. Moreover, the composite materials exhibited a positive solidification effect on heavy metals present in CPG.http://www.sciencedirect.com/science/article/pii/S2238785423006580Calcined phosphogypsumCementDeterioration coefficientHydration heatHeavy metal leachingCompressive strength |
| spellingShingle | Fang Deng Jian Ye Yanling Liu Tianxiao Zhang Yishun Liao Shengwen Tang Influence of cement on properties of calcined phosphogypsum based composite cementitious materials Journal of Materials Research and Technology Calcined phosphogypsum Cement Deterioration coefficient Hydration heat Heavy metal leaching Compressive strength |
| title | Influence of cement on properties of calcined phosphogypsum based composite cementitious materials |
| title_full | Influence of cement on properties of calcined phosphogypsum based composite cementitious materials |
| title_fullStr | Influence of cement on properties of calcined phosphogypsum based composite cementitious materials |
| title_full_unstemmed | Influence of cement on properties of calcined phosphogypsum based composite cementitious materials |
| title_short | Influence of cement on properties of calcined phosphogypsum based composite cementitious materials |
| title_sort | influence of cement on properties of calcined phosphogypsum based composite cementitious materials |
| topic | Calcined phosphogypsum Cement Deterioration coefficient Hydration heat Heavy metal leaching Compressive strength |
| url | http://www.sciencedirect.com/science/article/pii/S2238785423006580 |
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