Longitudinal single-sided NMR study : silica-to-alumina ratio changes the reaction mechanism of geopolymer
Li, Jing; Mailhiot, Sarah; Kantola, Anu M.; Niu, He; Sreenivasan, Harisankar; Telkki, Ville-Veikko; Kinnunen, Päivö (2022-07-27)
Li, J., Mailhiot, S., Kantola, A. M., Niu, H., Sreenivasan, H., Telkki, V.-V., & Kinnunen, P. (2022). Longitudinal single-sided NMR study: Silica-to-alumina ratio changes the reaction mechanism of geopolymer. Cement and Concrete Research, 160, 106921. https://doi.org/10.1016/j.cemconres.2022.106921
© 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
https://creativecommons.org/licenses/by/4.0/
https://urn.fi/URN:NBN:fi-fe2022102462935
Tiivistelmä
Abstract
Characterizing and understanding the mechanisms underlying geopolymerization are critical in achieving the use of sustainable construction material, geopolymer, for widespread commercial production. Non-destructive ¹H NMR relaxometry can provide novel information about geopolymerization as it allows simultaneous detection of where the water goes and how the pore structure changes. Coupled with the development of single-sided NMR devices, NMR measurements are not limited by the specimen size and are therefore able to observe in-situ conditions of geopolymer synthesis. Here, the curing process of metakaolin-based geopolymers was monitored by ¹H relaxometry on a single-sided NMR device. The silica-to-alumina ratio (Si/Al) was found to affect reaction stages of the geopolymerization. After the dissolution of aluminosilicate precursor, the low Si/Al of 1 was found to generate three gelation/polymerization stages as well as a water-binding stage, and two gel phases appeared. When Si/Al varied in 1.5–2.5, two gelation/polymerization stages and only one gel phase was observed.
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