Abstract
Although sodium aluminosilicate hydrate (NASH) gel governs the physicochemical properties of geopolymer concrete, its nucleation and growth mechanism remain poorly understood. Here, time-resolved cryogenic transmission electron microscopy (cryo-TEM), in addition to other characterization techniques, were applied to probe the nanostructural evolution of NASH gel from early age up to 7 days. We found that the nucleation and growth of NASH gel is not a one-step process and that intermediate phases precede the formation of the geopolymeric network. More specifically, we detected the formation of prenucleation clusters (~1–2 nm) in the first minute of geopolymerisation, which then agglomerated into partially polymerized globules (~15 nm). As geopolymerisation proceeded, these globules transformed into the more stable, highly polymerized NASH gel. These findings suggest the nucleation pathway of NASH can be more accurately depicted by non-classical nucleation theory, which paves the way for the development of more robust nanoscale models of geopolymer binders.
Original language | English |
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Article number | 106873 |
Number of pages | 12 |
Journal | Cement and Concrete Research |
Volume | 159 |
DOIs | |
Publication status | Published - Sept 2022 |
Keywords
- Calorimetry
- Characterization
- Cryo-TEM
- Geopolymer
- Metakaolin
- Reaction
- Spectroscopy
Equipment
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Monash Centre for Electron Microscopy (MCEM)
Sorrell, F. (Manager) & Miller, P. (Manager)
Office of the Vice-Provost (Research and Research Infrastructure)Facility/equipment: Facility
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Ramaciotti Centre for Cryo-Electron Microscopy (CryoEM)
Ramm, G. (Manager), Crawford, S. A. (Operator), Venugopal, H. (Operator), Clark, J. M. (Operator) & Gervinskas, G. (Operator)
Faculty of Medicine Nursing and Health Sciences Research PlatformsFacility/equipment: Facility