Monitoring depth and width of cracks in underwater concrete structures using embedded smart aggregates

This work devises a method to monitor the width and depth of cracks in underwater concrete structures employing active sensing technology based on embedded smart aggregates (SAs). To this end, an experimental platform is designed. Two SAs are pre-embedded in the underwater concrete beam to enable the excitation and acquisition of signals. The time-domain method analyzes the sensor signals, and wavelet packet decomposition is utilized to calculate the sensor signal energy. The sensor signal energy gradually decays with an increase in the depth of cracks in the concrete beams. However, as the width of the cracks increases, the main channel for stress wave propagation changes, causing the sensor signal energy to first decay and then increase. This paper also defines a damage index based on the depth of cracks in the underwater concrete beams to describe the crack depth damage.