Thermodynamic Stability and Dissolution of Calcium Fluoride of Phosphogypsum Solidified in Cement-Based Cementing Materials in Bicarbonate Solution
Cement-based cementitious materials present an alkaline environment and mainly exist in the form of Ca(OH)2. Phosphogypsum, as a retarder of cementitious materials, is often added to cement instead of gypsum, and the fluorine by-product of phosphogypsum is also fixed in the form of CaF2. These cemen...
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| Format: | Article |
| Language: | English |
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Kaunas University of Technology
2023-12-01
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| Series: | Medžiagotyra |
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| Online Access: | https://matsc.ktu.lt/index.php/MatSc/article/view/33694 |
| _version_ | 1797435893498249216 |
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| author | Jianhui FAN Xuebing WANG Shengbo GUO |
| author_facet | Jianhui FAN Xuebing WANG Shengbo GUO |
| author_sort | Jianhui FAN |
| collection | DOAJ |
| description | Cement-based cementitious materials present an alkaline environment and mainly exist in the form of Ca(OH)2. Phosphogypsum, as a retarder of cementitious materials, is often added to cement instead of gypsum, and the fluorine by-product of phosphogypsum is also fixed in the form of CaF2. These cement-based materials often serve in environments containing carbonate groundwater, which changes the stability of solidified CaF2. This paper studied the solid and liquid changes in Ca(OH)2-CaF2, Ca(OH)2-CaF2-HCO3, CaF2-HCO3-OH systems, and therefore studied the solubility of the by-product CaF2 of phosphogypsum in the groundwater containing HCO3- anion after curing in the cement-based cementitious system through experiments and thermodynamic equation simulation. The results showed that the dissolved Ca2+ of Ca(OH)2 led to the dissolution of CaF2, which led to a significant reduction in the F- anion concentration. However, with the increase of HCO3- concentration in groundwater, the F- anion concentration of Ca(OH)2-CaF2-HCO3 system increased, and the main product formed in the solid phase was calcium carbonate; The dissolution of F- anions in CaF2-HCO3-OH system also increased with the increase of HCO3- concentration. Therefore, the influence of HCO3- in groundwater should be considered when using phosphogypsum instead of gypsum as a retarder in cement-based cementitious materials. |
| first_indexed | 2024-03-09T10:53:53Z |
| format | Article |
| id | doaj.art-f3e8bbc205674c788ee31e5766596e4e |
| institution | Directory Open Access Journal |
| issn | 1392-1320 2029-7289 |
| language | English |
| last_indexed | 2024-03-09T10:53:53Z |
| publishDate | 2023-12-01 |
| publisher | Kaunas University of Technology |
| record_format | Article |
| series | Medžiagotyra |
| spelling | doaj.art-f3e8bbc205674c788ee31e5766596e4e2023-12-01T04:27:57ZengKaunas University of TechnologyMedžiagotyra1392-13202029-72892023-12-0129446847310.5755/j02.ms.3369438948Thermodynamic Stability and Dissolution of Calcium Fluoride of Phosphogypsum Solidified in Cement-Based Cementing Materials in Bicarbonate SolutionJianhui FAN0Xuebing WANG1Shengbo GUO2Hubei University of Arts and ScienceHubei University of Arts and ScienceHubei University of Arts and ScienceCement-based cementitious materials present an alkaline environment and mainly exist in the form of Ca(OH)2. Phosphogypsum, as a retarder of cementitious materials, is often added to cement instead of gypsum, and the fluorine by-product of phosphogypsum is also fixed in the form of CaF2. These cement-based materials often serve in environments containing carbonate groundwater, which changes the stability of solidified CaF2. This paper studied the solid and liquid changes in Ca(OH)2-CaF2, Ca(OH)2-CaF2-HCO3, CaF2-HCO3-OH systems, and therefore studied the solubility of the by-product CaF2 of phosphogypsum in the groundwater containing HCO3- anion after curing in the cement-based cementitious system through experiments and thermodynamic equation simulation. The results showed that the dissolved Ca2+ of Ca(OH)2 led to the dissolution of CaF2, which led to a significant reduction in the F- anion concentration. However, with the increase of HCO3- concentration in groundwater, the F- anion concentration of Ca(OH)2-CaF2-HCO3 system increased, and the main product formed in the solid phase was calcium carbonate; The dissolution of F- anions in CaF2-HCO3-OH system also increased with the increase of HCO3- concentration. Therefore, the influence of HCO3- in groundwater should be considered when using phosphogypsum instead of gypsum as a retarder in cement-based cementitious materials.https://matsc.ktu.lt/index.php/MatSc/article/view/33694fluorine anionbicarbonateraman spectrumthermodynamic equilibrium |
| spellingShingle | Jianhui FAN Xuebing WANG Shengbo GUO Thermodynamic Stability and Dissolution of Calcium Fluoride of Phosphogypsum Solidified in Cement-Based Cementing Materials in Bicarbonate Solution Medžiagotyra fluorine anion bicarbonate raman spectrum thermodynamic equilibrium |
| title | Thermodynamic Stability and Dissolution of Calcium Fluoride of Phosphogypsum Solidified in Cement-Based Cementing Materials in Bicarbonate Solution |
| title_full | Thermodynamic Stability and Dissolution of Calcium Fluoride of Phosphogypsum Solidified in Cement-Based Cementing Materials in Bicarbonate Solution |
| title_fullStr | Thermodynamic Stability and Dissolution of Calcium Fluoride of Phosphogypsum Solidified in Cement-Based Cementing Materials in Bicarbonate Solution |
| title_full_unstemmed | Thermodynamic Stability and Dissolution of Calcium Fluoride of Phosphogypsum Solidified in Cement-Based Cementing Materials in Bicarbonate Solution |
| title_short | Thermodynamic Stability and Dissolution of Calcium Fluoride of Phosphogypsum Solidified in Cement-Based Cementing Materials in Bicarbonate Solution |
| title_sort | thermodynamic stability and dissolution of calcium fluoride of phosphogypsum solidified in cement based cementing materials in bicarbonate solution |
| topic | fluorine anion bicarbonate raman spectrum thermodynamic equilibrium |
| url | https://matsc.ktu.lt/index.php/MatSc/article/view/33694 |
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