Understanding Acoustic Emission Testing- Reading 1 Part B-A

16.7.9 Bond in Reinforced Concrete
A number of acoustic emission studies of debonding of reinforcing bars in
reinforced concrete have been carried out. Kobayashi et al. tested simulated
beam-column connections with a 90° hooked reinforcing bar subjected to
various cyclic loading histories. They found that the penetration of a surface
crack down to the level of the bar gave rise to only one or two acoustic events;
most acoustic emission signals were generated by the internal cracking
around the bar due to fracture at the lugs (ribs) of the bars. Acoustic emission
signals were able to indicate, with reasonable accuracy, the degree of
debonding. They suggested that acoustic emission techniques could be used
to determine the amount of bond deterioration in concrete structures during
proof testing, or due to overloads. In addition, several studies of bond
degradation at elevated temperatures have been carried out. Royles et al.
studied simple pullout specimens at temperatures up to 800°C.
Charlie Chong/ Fion Zhang