The Influences of Soluble Phosphorus on Hydration Process and Mechanical Properties of Hemihydrate Gypsum under Deep Retarding Condition
Phospho-gypsum is an industrial solid waste discharged from the phosphate production process. The waste includes complex impurities such as phosphoric acid and its salts, fluoride, and organics. Usually, retarders are mixed in gypsum-based building materials to extend setting time. Although the effe...
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| author | Puyue Fan Mingtao Zhang Min Zhao Jiahui Peng Kai Gao Jing Huang Wei Yi Cong Zhu |
| author_facet | Puyue Fan Mingtao Zhang Min Zhao Jiahui Peng Kai Gao Jing Huang Wei Yi Cong Zhu |
| author_sort | Puyue Fan |
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| description | Phospho-gypsum is an industrial solid waste discharged from the phosphate production process. The waste includes complex impurities such as phosphoric acid and its salts, fluoride, and organics. Usually, retarders are mixed in gypsum-based building materials to extend setting time. Although the effects of the impurities on hydration properties and the mechanical strength of calcined gypsum have been analyzed, the impact and mechanism of soluble phosphorus on the phospho-gypsum under retardation is yet to be defined. In this study, we employed thermogravimetry (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM) to evaluate the hydration kinetics, phase transformation, structure, and morphology of the calcined gypsum. The data showed that the retarder or soluble phosphorus prolonged the setting time. A single retarder considerably shortened the initial setting time from 95 min to 60 min, even at the lowest dosage of 0.1 wt.% soluble phosphorus. In addition, drying flexural and compressive strengths were markedly decreased. On the other hand, the induction period was advanced with extension of acceleration and deceleration stage. SEM results indicated that the crystal morphology of the gypsum changed from a long to short column or block. An EDS analysis showed that phosphates were concentrated on the surface of gypsum crystals. |
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| issn | 1996-1944 |
| language | English |
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| spelling | doaj.art-ed8d55c18acc4c3e89a1d25d89a4b7c62023-11-30T23:35:29ZengMDPI AGMaterials1996-19442022-04-01157268010.3390/ma15072680The Influences of Soluble Phosphorus on Hydration Process and Mechanical Properties of Hemihydrate Gypsum under Deep Retarding ConditionPuyue Fan0Mingtao Zhang1Min Zhao2Jiahui Peng3Kai Gao4Jing Huang5Wei Yi6Cong Zhu7College of Materials Science and Engineering, Chongqing University, Chongqing 400045, ChinaCollege of Materials Science and Engineering, Chongqing University, Chongqing 400045, ChinaSchool of Civil and Architectural Engineering, Yangtze Normal University, Chongqing 408100, ChinaCollege of Materials Science and Engineering, Chongqing University, Chongqing 400045, ChinaCollege of Materials Science and Engineering, Chongqing University, Chongqing 400045, ChinaCollege of Materials Science and Engineering, Chongqing University, Chongqing 400045, ChinaCollege of Materials Science and Engineering, Chongqing University, Chongqing 400045, ChinaCollege of Civil Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, ChinaPhospho-gypsum is an industrial solid waste discharged from the phosphate production process. The waste includes complex impurities such as phosphoric acid and its salts, fluoride, and organics. Usually, retarders are mixed in gypsum-based building materials to extend setting time. Although the effects of the impurities on hydration properties and the mechanical strength of calcined gypsum have been analyzed, the impact and mechanism of soluble phosphorus on the phospho-gypsum under retardation is yet to be defined. In this study, we employed thermogravimetry (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM) to evaluate the hydration kinetics, phase transformation, structure, and morphology of the calcined gypsum. The data showed that the retarder or soluble phosphorus prolonged the setting time. A single retarder considerably shortened the initial setting time from 95 min to 60 min, even at the lowest dosage of 0.1 wt.% soluble phosphorus. In addition, drying flexural and compressive strengths were markedly decreased. On the other hand, the induction period was advanced with extension of acceleration and deceleration stage. SEM results indicated that the crystal morphology of the gypsum changed from a long to short column or block. An EDS analysis showed that phosphates were concentrated on the surface of gypsum crystals.https://www.mdpi.com/1996-1944/15/7/2680hemihydrate gypsumsoluble phosphorushydration processmechanical propertiesmechanism |
| spellingShingle | Puyue Fan Mingtao Zhang Min Zhao Jiahui Peng Kai Gao Jing Huang Wei Yi Cong Zhu The Influences of Soluble Phosphorus on Hydration Process and Mechanical Properties of Hemihydrate Gypsum under Deep Retarding Condition Materials hemihydrate gypsum soluble phosphorus hydration process mechanical properties mechanism |
| title | The Influences of Soluble Phosphorus on Hydration Process and Mechanical Properties of Hemihydrate Gypsum under Deep Retarding Condition |
| title_full | The Influences of Soluble Phosphorus on Hydration Process and Mechanical Properties of Hemihydrate Gypsum under Deep Retarding Condition |
| title_fullStr | The Influences of Soluble Phosphorus on Hydration Process and Mechanical Properties of Hemihydrate Gypsum under Deep Retarding Condition |
| title_full_unstemmed | The Influences of Soluble Phosphorus on Hydration Process and Mechanical Properties of Hemihydrate Gypsum under Deep Retarding Condition |
| title_short | The Influences of Soluble Phosphorus on Hydration Process and Mechanical Properties of Hemihydrate Gypsum under Deep Retarding Condition |
| title_sort | influences of soluble phosphorus on hydration process and mechanical properties of hemihydrate gypsum under deep retarding condition |
| topic | hemihydrate gypsum soluble phosphorus hydration process mechanical properties mechanism |
| url | https://www.mdpi.com/1996-1944/15/7/2680 |
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