A feasibility study of detecting reinforcing-bar debonding by acoustic-emission technique

Acoustic emissions (AE) detected by two transducers mounted on a reinforcing bar in a reinforced-concrete block, which is subjected to cyclic tension-compression loading, are used to assess the locations of re-bar debonding. Preliminary uniaxial-tension tests of the re-bar were conducted to establish the proper level of AE sensitivity which was then verified by uniaxial-tension tests of re-bar embedded in a concrete block. The main tests consist of simulated beamcolumn connection with a 90-deg hooked No. 8 Grade 60 rebar subjected to various cyclic-loading histories. Reasonably good correlations were established between the debonding regions indicated by the AE signals and those detached by dye injected into the cracked concrete.