Relationship between chloride ingress and concrete cover quality of inland structures exposed to deicing salts

Abstract

The apparent diffusion coefficient of chloride ions is used to evaluate the durability of existing concrete structures against chloride attack. The coefficient requires in situ measurements of chloride profiles, which use destructive sampling techniques, such as core drilling. In this study, the relationship between the apparent diffusion coefficient of chloride ions obtained from destructive tests and the air-permeability coefficient obtained from a non-nodestructive Torrent method in the existing road bridges exposed to deicing salts was analyzed. The obtained relationship was different from the common trends obtained from laboratory chloride-immersion tests and in situ measurements in marine/coastal concrete structures. Additional cyclic wetting and drying tests in a laboratory revealed the effects of environmental differences on the apparent diffusion coefficient of chloride ions. A higher ratio of the drying period, in the case of deicing salts, reduced the apparent diffusion coefficient.

Keywords

• Chloride attack
• Deicing salts
• Air permeability
• Durability
• Concrete bridge