Application of an Electromagnetic Method for Evaluation of Chlorine Distribution in Concrete

Presence of chloride ions in cover concrete leads to an enhanced ­deterioration of reinforced concrete structures. Prediction of the resultant damage in early stages of development is not possible, unless the distributions of chloride ions across the concrete section are known. This paper presents an on-going study of evaluating such distribution by a non-destructive method using electromagnetic wave. The technology is introduced in a separate paper in the symposium, shows in laboratory experiments its applicability to structures whose concrete properties are known. The ability to estimating the said distribution in cross section in existing concrete structure has been investigated in field tests and the method to be equally usable has been found by modifications of the method based on actual concrete properties in question. Once established, the method will ­provide a valuable means of readily collecting, not a limited and point-based data from cores, but information of area-wide chlorine ions non-destructively. This should, in turn, allow the owner of the concrete structure to identify chlorine deterioration at an early stage and to formulate effective strategies against the resultant damage.