Comprehensive study of moist curing duration and activator type on mechanical properties, shrinkage, and cracking of alkali-activated slag

Despite the considerable research efforts, shrinkage and cracking of alkali-activated slag (AAS) is still a delicate issue. One of the reasons is the enormous complexity of these materials, which originates from different activators, their different dosing, and different approaches for curing. There...

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Bibliographic Details
Published in:Construction & building materials 2024-02, Vol.416, p.135199, Article 135199
Main Authors: Kucharczyková, Barbara, Nápravník, Petr, Kocáb, Dalibor, Lisztwan, Dominik, Rovnaník, Pavel, Hajzler, Jan, Bílek, Vlastimil
Format: Article
Language:English
Subjects:
Activator type
Alkali activated slag
Cracking
Curing
Microstructure
Reaction rate
Resonance method
Shrinkage
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Summary:Despite the considerable research efforts, shrinkage and cracking of alkali-activated slag (AAS) is still a delicate issue. One of the reasons is the enormous complexity of these materials, which originates from different activators, their different dosing, and different approaches for curing. Therefore, the effect of the duration of moist curing of AAS pastes with the three most common sodium activator types (hydroxide, waterglass, carbonate) of the same molarity 4M Na+) and the same starting slag volume fraction (0.52) on their mechanical properties, shrinkage, and cracking performance was complexly investigated throughout one year. Shrinkage was assessed manually by measuring length changes and automatically using embedded strain gauges. A non-destructive resonance method was newly applied to monitor the evolution of cracking over time, including the physical closure of cracks. The obtained results emphasise the fundamental role of an activator for curing effectiveness based on the rate of reaction and microstructural refinement. •The effect of moist curing distinctively differs for pastes with different activators.•Close relation between the reaction rate, microstructure, and effect of moist curing duration.•The use of embedded strain gauges for long-term continuous shrinkage monitoring introduced.•The resonance method was found very useful for monitoring cracking behaviour over time.•Initial cracking due to shrinkage and moisture gradient followed by physical closing of the cracks.
ISSN:0950-0618
1879-0526
DOI:10.1016/j.conbuildmat.2024.135199