Research on Sulfate Attack Mechanism of Cement Concrete Based on Chemical Thermodynamics
Based on principles of chemical thermodynamics, the relationship between temperature and the Gibbs free energy of erosion products generated during the sulfate attack on cement concrete was deduced. The orientation of chemical reactions of sulfate attack on cement concrete was theoretically determin...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2020-01-01
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| Series: | Advances in Materials Science and Engineering |
| Online Access: | http://dx.doi.org/10.1155/2020/6916039 |
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| author | Peng Liu Ying Chen Zhiwu Yu Lingkun Chen Yongfeng Zheng |
| author_facet | Peng Liu Ying Chen Zhiwu Yu Lingkun Chen Yongfeng Zheng |
| author_sort | Peng Liu |
| collection | DOAJ |
| description | Based on principles of chemical thermodynamics, the relationship between temperature and the Gibbs free energy of erosion products generated during the sulfate attack on cement concrete was deduced. The orientation of chemical reactions of sulfate attack on cement concrete was theoretically determined as well as the critical sulfate ion concentration and the formation conditions of erosion products. The phase composition, microstructure, crystal form, and morphology of erosion products before and after sulfate attack were investigated by environmental scanning electron microscope and energy spectrum analysis (ESEM-EDS) and X-ray diffraction (XRD). The results show that the effects of sulfate ion concentration and temperature on cement concrete sulfate attack are significant, and different influencing factors correlate with each other. The crystal transition temperature between the anhydrite and dihydrate gypsum is 42°C, and the corresponding concentration of sulfate ion is about 2.3 × 10−3 mol/L. Simultaneously, the crystal transition temperature between the thenardite and mirabilite is 32.4°C. Moreover, the theoretical upper limit temperature and sulfate ion lower limit concentration of thaumasite are 44°C and 0.0023 mol/L, respectively. The ESEM-EDS and XRD results imply that the chemical thermodynamics can be used to reveal the erosion mechanism of sulfate attack on cement concrete. The major erosion products of sulfate attack on cement concrete are rod-like ettringite with a larger slenderness ratio, plate-like gypsum, granular sulfate salt, incompletely corroded calcium hydroxide, and residual skeleton of calcium silicate hydrate. The sulfate attack has double effects on mechanical properties of specimens, which can affect the microstructure, phase composition, type, and morphology of erosion products. |
| format | Article |
| id | doaj-art-19193d9c25d1488a999a0fb05870f2cf |
| institution | Kabale University |
| issn | 1687-8434 1687-8442 |
| language | English |
| publishDate | 2020-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Advances in Materials Science and Engineering |
| spelling | doaj-art-19193d9c25d1488a999a0fb05870f2cf2025-02-03T05:49:29ZengWileyAdvances in Materials Science and Engineering1687-84341687-84422020-01-01202010.1155/2020/69160396916039Research on Sulfate Attack Mechanism of Cement Concrete Based on Chemical ThermodynamicsPeng Liu0Ying Chen1Zhiwu Yu2Lingkun Chen3Yongfeng Zheng4School of Civil Engineering, Central South University, 22 Shaoshan Road, Changsha 410075, ChinaSchool of Civil Engineering, Central South University, 22 Shaoshan Road, Changsha 410075, ChinaSchool of Civil Engineering, Central South University, 22 Shaoshan Road, Changsha 410075, ChinaSchool of Civil Engineering, Southwest Jiaotong University, 6 Jingqu Road, Chengdu 610031, ChinaKey Laboratory of Building Structural Retrofitting and Underground Space Engineering, Shandong Jianzhu University, Ministry of Education, Jinan, Shandong 250101, ChinaBased on principles of chemical thermodynamics, the relationship between temperature and the Gibbs free energy of erosion products generated during the sulfate attack on cement concrete was deduced. The orientation of chemical reactions of sulfate attack on cement concrete was theoretically determined as well as the critical sulfate ion concentration and the formation conditions of erosion products. The phase composition, microstructure, crystal form, and morphology of erosion products before and after sulfate attack were investigated by environmental scanning electron microscope and energy spectrum analysis (ESEM-EDS) and X-ray diffraction (XRD). The results show that the effects of sulfate ion concentration and temperature on cement concrete sulfate attack are significant, and different influencing factors correlate with each other. The crystal transition temperature between the anhydrite and dihydrate gypsum is 42°C, and the corresponding concentration of sulfate ion is about 2.3 × 10−3 mol/L. Simultaneously, the crystal transition temperature between the thenardite and mirabilite is 32.4°C. Moreover, the theoretical upper limit temperature and sulfate ion lower limit concentration of thaumasite are 44°C and 0.0023 mol/L, respectively. The ESEM-EDS and XRD results imply that the chemical thermodynamics can be used to reveal the erosion mechanism of sulfate attack on cement concrete. The major erosion products of sulfate attack on cement concrete are rod-like ettringite with a larger slenderness ratio, plate-like gypsum, granular sulfate salt, incompletely corroded calcium hydroxide, and residual skeleton of calcium silicate hydrate. The sulfate attack has double effects on mechanical properties of specimens, which can affect the microstructure, phase composition, type, and morphology of erosion products.http://dx.doi.org/10.1155/2020/6916039 |
| spellingShingle | Peng Liu Ying Chen Zhiwu Yu Lingkun Chen Yongfeng Zheng Research on Sulfate Attack Mechanism of Cement Concrete Based on Chemical Thermodynamics Advances in Materials Science and Engineering |
| title | Research on Sulfate Attack Mechanism of Cement Concrete Based on Chemical Thermodynamics |
| title_full | Research on Sulfate Attack Mechanism of Cement Concrete Based on Chemical Thermodynamics |
| title_fullStr | Research on Sulfate Attack Mechanism of Cement Concrete Based on Chemical Thermodynamics |
| title_full_unstemmed | Research on Sulfate Attack Mechanism of Cement Concrete Based on Chemical Thermodynamics |
| title_short | Research on Sulfate Attack Mechanism of Cement Concrete Based on Chemical Thermodynamics |
| title_sort | research on sulfate attack mechanism of cement concrete based on chemical thermodynamics |
| url | http://dx.doi.org/10.1155/2020/6916039 |
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