Evaluation of deterioration and specification of defect of RC structure by natural potential and external impact-acoustic methods

It is a worldwide problem to build safer reinforced concrete (under-mentioned RC) structures on reflection of the great Hanshin earthquake disaster in 1995, Japan. The researches on the durability and the earthquake proof have advanced and the various countermeasures for these have been proposed. This paper deals with the specification of deterioration zones and its reliance, by using an external impact-acoustic detector, newly developed, which enables us to examine nondestructively the corrosive state of the inside of a concrete structure, and furthermore the verification with the natural potential method. The main experimental results concerning the building used in common are as follows:(1) The macroscopical corrosive degree of the RC structure can be evaluated by measuring the natural potential by means of the CuCuSO4 half cell and the effectiveness of the corrosion map. (2) “The external impact-acoustic method” can specify precisely the corrosive parts of reinforcement without the least damage on the RC structure, although the judgment of the corrosive grade is difficult; so, this disadvantage must be covered by using the natural potential method at the same time. (3)The relationship between the natural potential method and the external impact-acoustic one is quantitatively analyzed concerning an existing building.