Detection of the corrosion damage of rebar in concrete using impact-echo method

The main purpose of this study is focused on the feasibility, reliability, and applicability of detecting the rebar (reinforcing steel bar) corrosion in concrete blocks by using impact-echo method associated with three electrochemical methods; that is open-circuit potential (OCP), direct current (DC) polarization, and alternating current (AC) impedance. The result of present study indicates that the impact-echo method can certainly detect the development of microcrack in the concrete blocks. With respect to predicting corrosion damage, the displacement spectrum obtained from the impact-echo method should be transferred as acceleration spectrum. Thus, the degree of corrosion damage can be predicted from relative amplitude obtained from acceleration spectrum. The OCP method can evaluate the corrosion state of steel in concrete. However, it is not useful in predicting the corrosion damage of the interior of the specimen. Both the DC polarization and AC impedance methods can predict the corrosion rate. The corrosion thickness of specimen obtained from integrating the corrosion rate can directly evaluate corrosion damage. It is very obvious that the proposed method can be applied to the nondestructive testing for reinforced concrete (RC) structures. (C) 2001 Elsevier Science Ltd. All rights reserved.