FLEXURAL FAILURE BEHAVIOR OF RC BEAMS WITH REBAR COR- ROSION AND DAMAGE EVALUATION BY ACOUSTIC EMMISSION

It is important to interpret and evaluate the fracture mechanism of deteriorated concrete structures with rebar corrosion. Monitoring by means of acoustic emission (AE) technique based on the clarified fracture process of the deteriorated concrete is also useful for maintenance scheme. This paper presents an experimental investigation on the flexural failure behavior of RC beams having different weight loss of 0, 5, 10 and 30% due to corrosion. AE was also monitored during the loading tests of the deteriorated concrete beams. As corrosion levels represented by weight loss increased, load carrying capacity of the beams decreased dramatically. In the case of the severest damage having weight loss of 30%, the rebar was eventually broken at the final stage. The mechanical behavior was attributed to the decrease of cross section of rebar and deterioration of bond properties (debonding) between concrete and rebar with corrosion. The deterioration of bond properties also provided the decrease of number of cracks within the beams. Regarding observation of AE activity, the number of AE events in the beams increased with increasing the corrosion levels, especially as it became more intense at the initial loading level before yielding of rebar. The bond deterioration in the beams with corrosion might occur around the rebar at an early loading stage. The AE sensors attached directly onto the rebar detected more AE signals with lower frequency than that of concrete. It was concluded that such detected AE signals with lower frequency appear to be generated by debonding behavior due to corrosion.