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 electr ochemical methods; that is open-circuit potential (OCP), direct current (DC ) polarization, and alternating current (AC) impedance. The result of prese nt study indicates that the impact-echo method can certainly detect the dev elopment of microcrack in the concrete blocks. With respect to predicting c orrosion damage, the displacement spectrum obtained from the impact-echo me thod should be transferred as acceleration spectrum. Thus, the degree of co rrosion damage can be predicted from relative amplitude obtained from accel eration spectrum. The OCP method can evaluate the corrosion state of steel in concrete. However, it is not useful in predicting the corrosion damage o f the interior of the specimen. Both the DC polarization and AC impedance m ethods can predict the corrosion rate. The corrosion thickness of specimen obtained from integrating the corrosion rate can directly evaluate corrosio n damage. It is very obvious that the proposed method can be applied to the nondestructive testing for reinforced concrete (RC) structures. (C) 2001 E lsevier Science Ltd. All rights reserved.