Zhu, X, Li, Q, Xiong, D et al. (3 more authors) (2021) Compositional-structural Gradient Change of C(N)-A-S-H(I) Gel in Alkali-activated Slag after Magnesium Sulphate Attack. Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society, 49 (10). pp. 2276-2285. ISSN 0454-5648
Abstract
This paper presented the gradient changes of the characteristics of C(N)-A-S-H (Calcium(Sodium)-Aluminium-Silicate Hydrates) gel in alkali-activated slag (AAS) mortars subjected to sulphate attack in 10% (in mass fraction) MgSO4 solution by 29Si solid-state magic-angle Spinning nuclear magnetic resonance (SS MAS-NMR), and high-resolution transmission electron microscopy-energy dispersive X-ray spectroscopy (HR TEM-EDX). The results show that the outer layer with the thickness of 0.5-3 mm after attack is mainly composed of Si-Al gel, the middle-level layer with the thickness of 3-6 mm is M/C(N)-A-S-H gel, and the internal layer with the thickness of 6-9 mm is mainly composed of C(N)-A-S-H gel (which was almost not attacked. The stable crystal tobermorite (Ca/Si ratio=0.98) and hydrotalcite-like phase (Mg/Al ratio=2.39) could not be destroyed by sulphate attack. However, the main chain of C(N)-A-S-H gel is readily attacked by sulphate at [AlO4] bridging tetrahedra (BT). Meanwhile, the magnesium sulphate initially results in de-calcium phenomenon (Mg will replace Ca), and then generates the de-aluminium phenomenon, finally forming the Si-Al gel (main product in the out layer) when removing Ca and partial Al from the gel and charge-balancing the gel by abundant Mg ions.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Civil Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 08 Dec 2021 14:31 |
Last Modified: | 08 Dec 2021 14:45 |
Status: | Published |
Publisher: | China Silicate Society |
Identification Number: | 10.14062/j.issn.0454-5648.20200918 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:181232 |