Assessing the bond behaviour of corroded smooth and ribbed rebars with acoustic emission monitoring

Corrosion of the reinforcement is one of the major deterioration problems in existing reinforced concrete (RC) structures. One of the important damage modes is the deterioration of the bond between steel and concrete. In this paper, the acoustic emission (AE) technique is evaluated for damage detection, characterisation and localisation during the corrosion process and during pull-out tests. AE monitoring is applied during accelerated corrosion as well as during pull-out tests, in combination with standard inspection techniques such as crack width measurements. RC prisms with smooth or ribbed reinforcement were corroded up to different corrosion levels: 0%, 1.5%, 5% and 10% mass loss. The corrosion process was accelerated in the laboratory. One of the specimens of each rebar type at every corrosion level was monitored continuously with the AE technique. At the target corrosion levels, pull-out tests were carried out to study the bond capacity. During these tests, AE monitoring was performed on every specimen. Results show that AE is able to detect damage during the corrosion progress and that the moment of crack initiation can be determined from the cumulative AE event curves. During the pull-out tests, debonding damage was successfully detected, characterised and located based on AE data.