On drying shrinkage in alkali-activated concrete: Improving dimensional stability by aging or heat-curing

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• 作者：R.J. Thomas ^{thomasrj@clarkson.edu} ; Diego Lezama ^{lezamads@clarkson.edu} ; Sulapha Peethamparan ; ^{speetham@clarkson.edu}
• 关键词：Alkali-activated concrete ; Drying shrinkage ; Autogenous shrinkage ; Fly ash ; Slag cement
• 刊名：Cement and Concrete Research
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：91
• 期：Complete
• 页码：13-23
• 全文大小：1887 K
• 卷排序：91

文摘

The problem of excessive drying shrinkage in alkali-activated concrete (AAC) is well-documented in the literature. The magnitude of drying shrinkage is often three or more times that in portland cement concrete. This study investigates the effects of binder type, activator concentration, strength, age, and curing method on the manifestation of drying shrinkage in alkali-activated fly ash and slag cement concrete. Early-age shrinkage strains in excess of 1200 με (0.12 percent strain) are observed in AAC. This is attributed to delayed hydration, microstructure refinement, and strength development. The resulting damage is far more significant than in portland cement concrete. Shrinkage and resulting damage are greatly reduced when specimens are dried at later age and after heat-curing. Alkali-activated slag cement concrete is more sensitive to water loss than portland cement or alkali-activated fly ash concrete. This results from a finer pore structure in alkali-activated slag binders.