University of Oulu

Li, J., Mailhiot, S., Sreenivasan, H., Kantola, A. M., Illikainen, M., Adesanya, E., Kriskova, L., Telkki, V.-V., & Kinnunen, P. (2021). Curing process and pore structure of metakaolin-based geopolymers: Liquid-state 1H NMR investigation. Cement and Concrete Research, 143, 106394. https://doi.org/10.1016/j.cemconres.2021.106394

Curing process and pore structure of metakaolin-based geopolymers : liquid-state ¹H NMR investigation

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Author: Li, Jing1,2; Mailhiot, Sarah2; Sreenivasan, Harisankar1;
Organizations: 1Fibre and Particle Engineering Research Unit, Faculty of Technology, University of Oulu, P.O. Box 4300, FIN-90014 Oulu, Finland
2NMR Research Unit, Faculty of Science, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland
3KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, 3001 Leuven, Belgium
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.2 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe202102255935
Language: English
Published: Elsevier, 2021
Publish Date: 2021-02-25
Description:

Abstract

Geopolymers are emerging construction materials with lower carbon dioxide emissions compared to the conventional cementitious materials. The knowledge of the curing process and the related pore structures are important for optimizing the properties of these materials for different applications. The curing process and final pore structure are sensitive to the amount of used water, however the specifics are unclear. The curing process and pore structures of metakaolin-based geopolymers with a narrow water-to-solid (w/s) ratio (0.59–0.66) were monitored by nuclear magnetic resonance (NMR) relaxometry and cryoporometry. The 14-day curing process was investigated by monitoring the change of T₂ and T₁ relaxation times and water signal intensity. After the curing, the pore structures were characterized by 2D T₁-T₂ correlation and T₂-T₂ exchange measurements of absorbed water. The pore size distributions (PSDs) were measured with NMR cryoporometry and compared to nitrogen physisorption and mercury intrusion porosimetry (MIP) results. We found that the relaxation times decreased as the pore structure of the geopolymers matured during the curing while the dissolution and the condensation periods of the curing were distinguished by the changes in signal amplitude reflecting the proton density. After the curing, three distinct pore sizes and connectivity between pores were identified from T₁-T₂ and T₂-T₂ spectra. Their PSDs were measured, and they were found to correspond to two different pore sizes originating from the arrangement of clusters and defective pores. In the narrow w/s ratio (0.59–0.66), the curing times were the same for all samples when cured at 24 °C while the pore sizes were observed to increase as a function of the w/s ratio.

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Series: Cement and concrete research
ISSN: 0008-8846
ISSN-E: 1873-3948
ISSN-L: 0008-8846
Volume: 143
Article number: 106394
DOI: 10.1016/j.cemconres.2021.106394
OADOI: https://oadoi.org/10.1016/j.cemconres.2021.106394
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Subjects:
Funding: This work is funded by the University of Oulu Kvantum Institute under Emerging projects- program (Zero-CO2 cement concept via phase-separated nano-glass). S.M acknowledges the support of Academy of Finland (grant 321701). P.K. acknowledges financial support from Academy of Finland (grants 322085, 329477 and 326291). V.-V.T. acknowledges the financial support of the European Research Council (ERC) under Horizon 2020 (H2020/2018-2022/ERC grant agreement no. 772110), Academy of Finland (grants #289649, 294027 and 319216) and the CA15209 COST Action (EURELAX).
Academy of Finland Grant Number: 321701
322085
329477
326291
289649
294027
319216
Detailed Information: 321701 (Academy of Finland Funding decision)
322085 (Academy of Finland Funding decision)
329477 (Academy of Finland Funding decision)
326291 (Academy of Finland Funding decision)
289649 (Academy of Finland Funding decision)
294027 (Academy of Finland Funding decision)
319216 (Academy of Finland Funding decision)
Copyright information: © 2021 The Author(s). 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/