Pore Structure Characteristics and Reaction Mechanism of Fly Ash Geopolymer
Publication: Journal of Materials in Civil Engineering
Volume 36, Issue 9
Abstract
The hydration reaction mechanism of geopolymers is intimately linked to their composition and structure. Additionally, pore structure characteristics play a vital role in the properties of hardened geopolymer pastes, significantly influencing the material’s strength, impermeability, and thermal conductivity. In this study, fly ash geopolymer (FAG) was synthesized by utilizing NaOH, , and low-calcium fly ash. The pore structure characteristics of FAGs were analyzed using mercury intrusion porosimetry (MIP), and the fractal dimension of FAGs was calculated using the Menger sponge model () and a fractal model based on thermodynamic relationships (). Fourier infrared spectroscopy (FTIR), thermogravimetric differential thermal (TG/DTA), and scanning electron microscopy secondary electron phase (SEM-SE) were used to test the composition of the hydration products of FAGs and their microscopic morphology. The results showed that after 90 days of maintaining ambient temperature, the porosity of FAG is between 20% and 30%, and the most available pore size is 10–50 nm. The fractal dimension calculated using the analytical model based on thermodynamic relations can more comprehensively determine the pore structure characteristics of FAG. The geopolymerization reaction process of fly ash particles can be categorized into four primary processes, forming an amorphous aluminosilicate gel as the hydration product.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
This work was supported by the Joint Funds of the National Natural Science Foundation of China (U20A20324), the National Natural Science Foundation of China (52272016), the Dalian Science and Technology Innovation Fund Project (2023JJ12SN036), and the National Youth Science Fund Project of China (52308235).
Author contributions: Wanli Wang: Methodology, Formal analysis, Writing—original draft. Baomin Wang: Resources, Conceptualization, Writing—review and editing, Supervision.
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Published In
Journal of Materials in Civil Engineering
Volume 36 • Issue 9 • September 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Sep 1, 2023
Accepted: Feb 6, 2024
Published online: Jun 17, 2024
Published in print: Sep 1, 2024
Discussion open until: Nov 17, 2024
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