2011 Volume 65 Issue 1 Pages 400-405
Frost damage, which is the deterioration due to freeze and thaw of pore solution is causes scaling, pop-out and cracks on surface of concrete members, is an important issue in the durability of concrete structures in cold regions. Deicing agents are sprayed in order to prevent frost damage. By contrast, it has been reported that chlorides of deicing agents accelerate the deterioration due to frost damage under freeze-thaw environment. It is generally known that phase changes of hydration products, such as formation of friedel’s salt and ettringite, occur due to penetration of chloride ion. Ettringite formation leads volume expansion and cracks. Since the acceleration of frost damage due to chlorides penetration, the use of deicing agents which is not containing chloride ions, such as potassium acetate and calcium-magnesium acetate, has been proposing. However, it has not been shown that chemical alteration due to penetration of deicing agents influence on increase of strain and decrease of structural characteristic value with frost damage under freeze-thaw environment. Therefore, this study aimed to investigate the influence of deicing agents under freeze-thaw environment on 1）progress of frost damage, 2）phase changes of hydration products and 3）decrease of structural characteristic value. As the results, 1）penetration of deicing agents containing chloride ions influenced on the strain hysteresis and resulted in the increase of residual strain and water absorbing ratio, 2）ettringite formation with displacement and dissolution of monosulfate hydrates was a contributory factor for frost damage acceleration and 3）chemical alteration and increase of residual strain due to penetration of chlorides led decrease of tensile strength, elastic modulus and fractural energy.
