Microstructure of Dolostones of Different Geological Ages and Dedolomitization Reaction
Dolostone is widely distributed and commonly used as concrete aggregates. A large number of studies have shown that there are significant differences in the expansibility of different dolostones, and the key factors determining the expansibility of alkali carbonate rocks have not been clarified. In...
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2022-06-01
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| Online Access: | https://www.mdpi.com/1996-1944/15/12/4109 |
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| author | Zhiyuan Fan Zhongyang Mao Xiang Liu Lei Yi Tao Zhang Xiaojun Huang Min Deng |
| author_facet | Zhiyuan Fan Zhongyang Mao Xiang Liu Lei Yi Tao Zhang Xiaojun Huang Min Deng |
| author_sort | Zhiyuan Fan |
| collection | DOAJ |
| description | Dolostone is widely distributed and commonly used as concrete aggregates. A large number of studies have shown that there are significant differences in the expansibility of different dolostones, and the key factors determining the expansibility of alkali carbonate rocks have not been clarified. In this paper, rocks were selected from five different geological ages: Jixianian, Cambrian, Ordovician, Devonian, and Triassic ages. The ordering degree and the content of MgCO<sub>3</sub> of dolomites in rocks of different geological ages were determined by X-ray diffraction (XRD). The degree of dedolomitization reaction in rocks cured in 80 °C, 1 mol/L NaOH solution was determined by quantitative X-ray diffraction (QXRD). The morphology of dolomites in rocks was determined by a polarizing microscope. The products of the dedolomitization reaction were determined by field emission electron microscopy (FESEM-EDS). According to the test results, the following conclusions are drawn. There is a good positive correlation between ordering degree and the molar fraction of MgCO<sub>3</sub> of dolomites. When the MgCO<sub>3</sub> mole fraction of dolomites varies from 47.17% to 49.60%, the higher the MgCO<sub>3</sub> mole fraction, the greater the ordering degree of dolomite. By analyzing the degree of the dedolomitization reaction of different dolostone powders cured at 80 °C in 1 mol/L NaOH solution, it is found that the older the geological age of dolostone, the slower the dedolomitization reaction rate and the lower the degree of dedolomitization reaction. The lower the ordering degree of dolomite crystal in the same geological age, the faster the rate of dedolomitization reaction and the higher the degree of dedolomitization reaction. |
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| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-09T23:11:27Z |
| publishDate | 2022-06-01 |
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| series | Materials |
| spelling | doaj.art-2147f58f7b294075af20e9abf50ef4fc2023-11-23T17:42:45ZengMDPI AGMaterials1996-19442022-06-011512410910.3390/ma15124109Microstructure of Dolostones of Different Geological Ages and Dedolomitization ReactionZhiyuan Fan0Zhongyang Mao1Xiang Liu2Lei Yi3Tao Zhang4Xiaojun Huang5Min Deng6College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, ChinaCollege of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, ChinaCollege of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, ChinaCollege of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, ChinaCollege of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, ChinaCollege of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, ChinaCollege of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, ChinaDolostone is widely distributed and commonly used as concrete aggregates. A large number of studies have shown that there are significant differences in the expansibility of different dolostones, and the key factors determining the expansibility of alkali carbonate rocks have not been clarified. In this paper, rocks were selected from five different geological ages: Jixianian, Cambrian, Ordovician, Devonian, and Triassic ages. The ordering degree and the content of MgCO<sub>3</sub> of dolomites in rocks of different geological ages were determined by X-ray diffraction (XRD). The degree of dedolomitization reaction in rocks cured in 80 °C, 1 mol/L NaOH solution was determined by quantitative X-ray diffraction (QXRD). The morphology of dolomites in rocks was determined by a polarizing microscope. The products of the dedolomitization reaction were determined by field emission electron microscopy (FESEM-EDS). According to the test results, the following conclusions are drawn. There is a good positive correlation between ordering degree and the molar fraction of MgCO<sub>3</sub> of dolomites. When the MgCO<sub>3</sub> mole fraction of dolomites varies from 47.17% to 49.60%, the higher the MgCO<sub>3</sub> mole fraction, the greater the ordering degree of dolomite. By analyzing the degree of the dedolomitization reaction of different dolostone powders cured at 80 °C in 1 mol/L NaOH solution, it is found that the older the geological age of dolostone, the slower the dedolomitization reaction rate and the lower the degree of dedolomitization reaction. The lower the ordering degree of dolomite crystal in the same geological age, the faster the rate of dedolomitization reaction and the higher the degree of dedolomitization reaction.https://www.mdpi.com/1996-1944/15/12/4109geological agesdolostoneordering degreededolomitization reaction |
| spellingShingle | Zhiyuan Fan Zhongyang Mao Xiang Liu Lei Yi Tao Zhang Xiaojun Huang Min Deng Microstructure of Dolostones of Different Geological Ages and Dedolomitization Reaction Materials geological ages dolostone ordering degree dedolomitization reaction |
| title | Microstructure of Dolostones of Different Geological Ages and Dedolomitization Reaction |
| title_full | Microstructure of Dolostones of Different Geological Ages and Dedolomitization Reaction |
| title_fullStr | Microstructure of Dolostones of Different Geological Ages and Dedolomitization Reaction |
| title_full_unstemmed | Microstructure of Dolostones of Different Geological Ages and Dedolomitization Reaction |
| title_short | Microstructure of Dolostones of Different Geological Ages and Dedolomitization Reaction |
| title_sort | microstructure of dolostones of different geological ages and dedolomitization reaction |
| topic | geological ages dolostone ordering degree dedolomitization reaction |
| url | https://www.mdpi.com/1996-1944/15/12/4109 |
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