Blast Furnace Slag Hydration in an Alkaline Medium: Influence of Sodium Content and Sodium Hydroxide Molarity
Publication: Journal of Materials in Civil Engineering
Volume 32, Issue 12
Abstract
The reaction of blast furnace slag in sodium hydroxide (NaOH) solutions of different molarities is evaluated. The compressive strength of the activated slag does not scale with the molarity of NaOH. The primary reaction product in the activated slag is identified with calcium aluminosilicate hydrate [C(A)SH]. While the early reactivity of slag is enhanced at higher alkalinity, and the dissolution of slag increases with the molarity of NaOH, the quantity of C(A)SH in the hydrating system does not scale with the molarity of NaOH in the activated slag. From X-ray diffraction (XRD) analysis, an additional water-soluble, sodium-based amorphous product is identified in the reaction products. The water-soluble product, which does not contribute to strength, increases proportionately with the initial Na content in the solution. At higher molarity, there is a larger proportion of the water-soluble product relative to C(A)SH in the reaction products. The ratio and ratios in the C(A)SH gel are relatively invariant of the NaOH molarity in the activating solution. The compressive strength gain in the alkali-activated slag is determined by the quantities of C(A)SH and the intrinsic sodium-filled water-soluble 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 (XRD and FTIR scans).
Acknowledgments
The authors would like to acknowledge support from the Department of Science and Technology, Initiative to Promote Energy Efficient Habitant (I-PHEE) Grant No. TMD/CERI/BEE/2016/031.
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Published In
Journal of Materials in Civil Engineering
Volume 32 • Issue 12 • December 2020
Copyright
© 2020 American Society of Civil Engineers.
History
Received: Nov 27, 2019
Accepted: May 29, 2020
Published online: Sep 22, 2020
Published in print: Dec 1, 2020
Discussion open until: Feb 22, 2021
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