Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate Environments
The early mechanical performances of low-calcium fly ash (FFA)-based geopolymer (FFA–GEO) mortar can be enhanced by soda residue (SR). However, the resistance of SR–FFA–GEO mortar to acid or sulfate environments is unclear, owing to the various inorganic calcium salts in SR. The aim of this study wa...
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2021-02-01
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| Online Access: | https://www.mdpi.com/1996-1944/14/4/785 |
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| author | Xianhui Zhao Haoyu Wang Boyu Zhou Han Gao Yonghui Lin |
| author_facet | Xianhui Zhao Haoyu Wang Boyu Zhou Han Gao Yonghui Lin |
| author_sort | Xianhui Zhao |
| collection | DOAJ |
| description | The early mechanical performances of low-calcium fly ash (FFA)-based geopolymer (FFA–GEO) mortar can be enhanced by soda residue (SR). However, the resistance of SR–FFA–GEO mortar to acid or sulfate environments is unclear, owing to the various inorganic calcium salts in SR. The aim of this study was to investigate the long-term mechanical strengths of up to 360 d and evaluate the resistance of SR–FFA–GEO mortar to 5% HCl and 5% Na<sub>2</sub>SO<sub>4</sub> environments through the losses in compressive strength and mass. Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS) and Fourier Transform Infrared Spectrometer (FTIR) experiments were conducted for the SR–FFA–GEO mortars, both before and after chemical attack, to clarify the attack mechanism. The results show that the resistances of the SR–FFA–GEO mortar with 20% SR (namely M10) to 5% HCl and 5% Na<sub>2</sub>SO<sub>4</sub> environments are superior to those of cement mortar. The environmental HCl reacts with the calcites in SR to produce CaCl<sub>2</sub>, CO<sub>2</sub> and H<sub>2</sub>O to form more pores under HCl attack, and the environmental Na<sup>+</sup> cations from Na<sub>2</sub>SO<sub>4</sub> go into Si-O-Al network structure, to further enhance the strength of mortar under Na<sub>2</sub>SO<sub>4</sub> attack. These results provide the experimental basis for the durability optimization of SR–FFA–GEO mortars. |
| first_indexed | 2024-03-09T05:15:59Z |
| format | Article |
| id | doaj.art-6ebeec088a92456e9482283c33f50823 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-09T05:15:59Z |
| publishDate | 2021-02-01 |
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| series | Materials |
| spelling | doaj.art-6ebeec088a92456e9482283c33f508232023-12-03T12:45:55ZengMDPI AGMaterials1996-19442021-02-0114478510.3390/ma14040785Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate EnvironmentsXianhui Zhao0Haoyu Wang1Boyu Zhou2Han Gao3Yonghui Lin4School of Civil Engineering, Hebei University of Engineering, Handan 056038, ChinaTianjin University Renai College, Tianjin 301636, ChinaSchool of Civil and Transportation Engineering, Hebei University of Technology, Tianjin 300401, ChinaTianjin University Renai College, Tianjin 301636, ChinaSchool of Civil and Transportation Engineering, Hebei University of Technology, Tianjin 300401, ChinaThe early mechanical performances of low-calcium fly ash (FFA)-based geopolymer (FFA–GEO) mortar can be enhanced by soda residue (SR). However, the resistance of SR–FFA–GEO mortar to acid or sulfate environments is unclear, owing to the various inorganic calcium salts in SR. The aim of this study was to investigate the long-term mechanical strengths of up to 360 d and evaluate the resistance of SR–FFA–GEO mortar to 5% HCl and 5% Na<sub>2</sub>SO<sub>4</sub> environments through the losses in compressive strength and mass. Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS) and Fourier Transform Infrared Spectrometer (FTIR) experiments were conducted for the SR–FFA–GEO mortars, both before and after chemical attack, to clarify the attack mechanism. The results show that the resistances of the SR–FFA–GEO mortar with 20% SR (namely M10) to 5% HCl and 5% Na<sub>2</sub>SO<sub>4</sub> environments are superior to those of cement mortar. The environmental HCl reacts with the calcites in SR to produce CaCl<sub>2</sub>, CO<sub>2</sub> and H<sub>2</sub>O to form more pores under HCl attack, and the environmental Na<sup>+</sup> cations from Na<sub>2</sub>SO<sub>4</sub> go into Si-O-Al network structure, to further enhance the strength of mortar under Na<sub>2</sub>SO<sub>4</sub> attack. These results provide the experimental basis for the durability optimization of SR–FFA–GEO mortars.https://www.mdpi.com/1996-1944/14/4/785geopolymerfly ashsoda residuechemical attackcompressive strengthmicrostructure |
| spellingShingle | Xianhui Zhao Haoyu Wang Boyu Zhou Han Gao Yonghui Lin Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate Environments Materials geopolymer fly ash soda residue chemical attack compressive strength microstructure |
| title | Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate Environments |
| title_full | Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate Environments |
| title_fullStr | Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate Environments |
| title_full_unstemmed | Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate Environments |
| title_short | Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate Environments |
| title_sort | resistance of soda residue fly ash based geopolymer mortar to acid and sulfate environments |
| topic | geopolymer fly ash soda residue chemical attack compressive strength microstructure |
| url | https://www.mdpi.com/1996-1944/14/4/785 |
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