Effect of Solution-to-Binder Ratio and Molarity on Volume Changes in Slag Binder Activated by Sodium Hydroxide at Early Age

Maïté Lacante, Brice Delsaute, Stéphanie Staquet

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1 Citation (Scopus)

Abstract

This research investigates the impact of solution concentration and solution-to-binder ratio (S/B) on the volume changes in alkali-activated slags with sodium hydroxide at 20 °C. Autogenous and thermal strains are monitored with a customized testing device in which thermal variations are controlled. Consequently, both the autogenous strain and coefficient of thermal expansion (CTE) are determined. Heat flow and internal relative humidity (IRH) are also monitored in parallel, making this research a multifaceted study. The magnitudes of autogenous strain and CTE are higher than those of ordinary Portland cement paste. Decreasing the solution concentration or S/B generally decreases the autogenous strain (swelling and shrinkage) and the CTE. The shrinkage amounted to 87 to 1981 µm/m, while the swelling reached between 27 and 295 µm/m and was only present in half of the compositions. The amplitude of the CTE, which increases up to 55 µm/m/°C for some compositions while the CTE of OPC remains between 20 and 25 µm/m/°C, can be explained by the high CTE of the solution in comparison with water. The IRH of paste cannot explain the autogenous strain’s development alone. Increasing S/B eliminates the self-desiccation-related decrease.
Original languageEnglish
Article number3308
Number of pages24
JournalMaterials
Volume17
Issue number13
DOIs
Publication statusPublished - Jul 2024

Bibliographical note

Funding Information:
This paper is the result of research actions performed in the framework of the FNRS-FWO-EOS project 30439691 \u2018INTERdisciplinary multiscale Assessment of a new generation of Concrete with alkali-activated maTerials\u2019 (https://interact.ulb.be/ (accessed on 30 August 2023)). The financial support by FNRS-FWO-EOS is gratefully acknowledged.

Publisher Copyright:
© 2024 by the authors.

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