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High-temperature behavior of geopolymer mortar containing nano-silica
Highlights Strength of GPM increases first and then decreases as the exposure temperature increases. NS shows different effects on the mechanical properties below and beyond 200 ℃. Geopolymer matrix is densified while the interfacial zone is damaged after heating. NS improves the compactness and stability of geopolymer before and after heating. Proposed damage model correlated well with the test data.
Abstract Nano-silica (NS) can significantly improve the microstructure, mechanical properties, and durability of metakaolin/fly ash-based geopolymer mortar (GPM). To investigate the high-temperature behavior of GPM containing NS, cubic compressive strength test, prism compressive strength test, flexural strength test, visual appearance analysis, thermal strain test, thermogravimetric and differential thermal analyses, bubble parameter test, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were conducted. The NS weight contents were 0 %, 0.5 %, 1.0 %, 1.5 %, 2.0 %, and 2.5 %, and the exposure temperatures were 25, 100, 200, 400, and 600 ℃. The results revealed that the sand in mortar constrained the development of cracks when the exposure temperature was 25–200 ℃, whereas cracks formed when the temperature was 200–600 ℃. From 25 to 200 ℃, a significant mass loss with slight geopolymer shrinkage was observed. In contrast, from 200 to 600 ℃, a slight mass loss with evident shrinkage occurred. The compressive and flexural strengths of the GPM first increased when the temperature was 25–200 ℃ and then decreased when the temperature was 200–600 ℃. When the temperature was less than 200 °C, NS improved the GPM strength; however, the strength decreased when the temperature exceeded 200 ℃. The latter occurred because NS enhanced the compactness of the GPM, resulting in increased pore pressure. Additionally, the thermal stability of the phases and sodium alumina silicate hydrate structure in the geopolymer was observed. The compactness and stability of the microstructure in the GPM were enhanced by NS. A damage model based on the cubic compressive strength that well describes the relationship between the exposure temperature and degree of damage was proposed.
High-temperature behavior of geopolymer mortar containing nano-silica
Highlights Strength of GPM increases first and then decreases as the exposure temperature increases. NS shows different effects on the mechanical properties below and beyond 200 ℃. Geopolymer matrix is densified while the interfacial zone is damaged after heating. NS improves the compactness and stability of geopolymer before and after heating. Proposed damage model correlated well with the test data.
Abstract Nano-silica (NS) can significantly improve the microstructure, mechanical properties, and durability of metakaolin/fly ash-based geopolymer mortar (GPM). To investigate the high-temperature behavior of GPM containing NS, cubic compressive strength test, prism compressive strength test, flexural strength test, visual appearance analysis, thermal strain test, thermogravimetric and differential thermal analyses, bubble parameter test, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were conducted. The NS weight contents were 0 %, 0.5 %, 1.0 %, 1.5 %, 2.0 %, and 2.5 %, and the exposure temperatures were 25, 100, 200, 400, and 600 ℃. The results revealed that the sand in mortar constrained the development of cracks when the exposure temperature was 25–200 ℃, whereas cracks formed when the temperature was 200–600 ℃. From 25 to 200 ℃, a significant mass loss with slight geopolymer shrinkage was observed. In contrast, from 200 to 600 ℃, a slight mass loss with evident shrinkage occurred. The compressive and flexural strengths of the GPM first increased when the temperature was 25–200 ℃ and then decreased when the temperature was 200–600 ℃. When the temperature was less than 200 °C, NS improved the GPM strength; however, the strength decreased when the temperature exceeded 200 ℃. The latter occurred because NS enhanced the compactness of the GPM, resulting in increased pore pressure. Additionally, the thermal stability of the phases and sodium alumina silicate hydrate structure in the geopolymer was observed. The compactness and stability of the microstructure in the GPM were enhanced by NS. A damage model based on the cubic compressive strength that well describes the relationship between the exposure temperature and degree of damage was proposed.
High-temperature behavior of geopolymer mortar containing nano-silica
Zhang, Peng (author) / Han, Xu (author) / Guo, Jinjun (author) / Hu, Shaowei (author)
2022-12-04
Article (Journal)
Electronic Resource
English
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