In this study, the corrosion-induced cracks and the corrosion of
rebar are experimentally evaluated in the dormant and acceleration
stages by applying the ultrasonic measurement. In the dormant
stage, the amplitude of the detected wave at 24 days
elapsed becomes smaller than that of no corrosion. The fact implies
that reflection scattering due to corrosion-induced cracking could
occur. Energy of waveform could recognize the attenuation of
ultrasonic wave due to corrosion-induced cracking. In the acceleration
stage, it is clarified that the ratio of the propagation distance
is characterized by the attenuation, which is closely correlated
with damage of rebar corrosion.
Thus, the applicability of the ultrasonic test to estimate the corrosion
of rebar and corrosion-induced cracking in concrete at the
early stage is confirmed.