Effect of Infilling of Air Voids by Ettringite on Resistance of Concretes to Freezing and Thawing

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Title: Effect of Infilling of Air Voids by Ettringite on Resistance of Concretes to Freezing and Thawing

Author(s): C. Ouyang and 0. J. lane

Publication: Special Publication

Volume: 177

Issue:

Appears on pages(s): 249-262

Keywords: air voids; durability; ettringite; fly ash; freezing and thawing; sulfate ions; wet-dry treatment

Date: 1/1/1999

Abstract:
The effect of infilling of air voids by ettringite on resistance of concretes to freezing and thawing was studied. Nine concrete mixtures, made with five cements with or without Class C fly ash, were exposed to freezing-thawing cycles following 110 to 222 days of moist curing. Prior to freezing-thawing, the specimens were examined by a low-vacuum scanning electron microscope (SEM) for the degree of infilling. It was found that the extent of the infilling depends on the length of moist curing as well as the wet/dry treatment. The infilling implies that these air voids are water-accessible. The function of the air-void system to protect concrete from freezing and thawing has been compromised due to the presence of water in some air voids. The infilling seems also to increase effective spacing factor. These might cause concrete to be more vulnerable to freezing-thawing damage.