Compensating for Concrete Shrinkage with High-Calcium Fly Ash

Compensating for Concrete Shrinkage with High-Calcium Fly Ash

Shrinkage of concrete during hardening is a serious problem in attempts to maintain the integrity of concrete structures. One of the methods of combating shrinkage is compensating for it using an expansive agent. The purpose of this work is to develop and study an expanding agent to concrete, includ...

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Bibliographic Details
Published in:Buildings (Basel) Vol. 14; no. 10; p. 3167
Main Authors: Barabanshchikov, Yurii, Krotova, Vasilia, Usanova, Kseniia
Format: Journal Article
Language:English
Published: Basel MDPI AG 01-10-2024
Subjects:
Additives
autogenous shrinkage
Bend strength
Calcium
Calcium nitrate
Cement
Cement hydration
Compressive strength
Concrete
Concrete structures
Deformation effects
Electrolytes
expansive agent
Expansive concrete
Fly ash
Foaming agents
Hardening
high-calcium fly ash
Nitrates
Russia
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Summary:Shrinkage of concrete during hardening is a serious problem in attempts to maintain the integrity of concrete structures. One of the methods of combating shrinkage is compensating for it using an expansive agent. The purpose of this work is to develop and study an expanding agent to concrete, including high-calcium fly ash and calcium nitrate as an expansion activator. The content of Ca(NO3)2 can be used to regulate the degree of expansion of the additive itself during hydration and, accordingly, to control shrinkage, thus obtaining shrinkage-free or expanding concrete. Shrinkage–expansion deformations of concrete can also be regulated by the amount of expanding additive replacing part of the cement. With the Ca(NO3)2 content of fly ash being 10% or more, concrete experiences expansion in the initial stages of hardening. The transition of deformation through 0 to the shrinkage region occurs depending on the composition and content of the additive after 8–15 days of hardening. It has been established that replacing cement with pure fly ash with a curing period of 90 days or more has virtually no effect on the strength of concrete, either in bending or in compression. The use of an expanding additive containing 5–15% Ca(NO3)2 reduces the strength of concrete by an average of 9%, despite the fact that calcium nitrate is a hardening accelerator.
ISSN:2075-5309
2075-5309
DOI:10.3390/buildings14103167