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, 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.

Авторы
Barabanshchikov Yurii1 , Krotova Vasilia1 , Usanova Kseniia 1, 2
Журнал
Издательство
MDPI Multidisciplinary Digital Publishing Institute
Номер выпуска
10
Язык
Английский
Страницы
3167
Статус
Опубликовано
Том
14
Год
2024
Организации
  • 1 Scientific and Technological Complex for Digital Engineering in Construction, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
  • 2 Academy of Engineering, RUDN University, 117198 Moscow, Russia
Ключевые слова
concrete; cement; high-calcium fly ash; calcium nitrate
Дата создания
04.11.2024
Дата изменения
04.11.2024
Постоянная ссылка
https://repository.rudn.ru/ru/records/article/record/157698/
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