In this study, a RC bridge wall rail affected by frost and salt actions was investigated in order to propose a maintenance planning of a RC structure subject to the combined attacks. A studied structure had been in service for more than forty years in Hokkaido in the northern part of Japan. Experimental results of material properties brought relationship between deterioration degrees of concrete and reinforcement. A compressive strength / Young’s modulus ratio was defined as the deterioration degree of concrete influenced by frost action and the deterioration degree of reinforcement was expressed by weight reduction rate. Further, the relationship was classified by degradation in appearance. On the assumption that the degradation in appearance depends on a balance between frost damage and salt damage, a developing process of the combined deterioration was observed. As a result, the deterioration degrees of concrete and reinforcement could be associated with the damage patterns. Especially, in case of the RC bridge wall rail with a loose concrete cover, the deterioration degree of concrete had a characteristic trend. Next, passage of time was considered and a time axis was added to the relationship between the deterioration degrees of concrete and reinforcement. Consequently, this relationship was proposed as assembly of damage developing process of a RC structure affected by combined frost and salt actions.
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