ABSTRACT
ABSTRACT. Concrete structures in the northern regions of Japan have a higher risk of deterioration due to freezing and thawing coming from the cold climate and heavy snows. The laboratory evaluation of resistance of concrete to freezing and thawing is studied actively in Japan, but there is still much left to be studied hereafter about the deterioration of concrete structures exposed in the field. A survey of the deterioration of concrete used in road bridges was made in Iwate Prefecture, a district in northeastern Japan. The number of bridges examined in this survey was 382. Many of the bridges were in greater or lesser degree damaged by freezing and thawing. The degree of deterioration differed according to the different parts of the bridges. Although the main cause of deterioration is presumed to be the result of poor construction, it can be pointed out that the lack of consideration for design of these structures adds significantly to their deterioration. In this paper, some designing methods for preventing frost damages of concrete are listed, based on the results of the survey.
