Embedded piezoelectric sensors for health monitoring of concrete structures

This paper presents an experimental investigation for detecting defects in concrete structures using so-called "smart aggregates." The smart aggregates are small cylinders with piezoelectric patches inside that can be embedded in concrete structures and used as both actuators and sensors. Specimens with different types of defects such as notch, hole, and inclusion were used in this study. To evaluate the effectiveness of the smart aggregates for detecting real cracks in concrete structures, three-point bending tests were carried out on two reinforced concrete beams. The test results indicate that not only the passive defects (notch, hole, or inclusion) but also the real cracks in reinforced concrete structures can be detected by the smart aggregates. Sensitivities of different parameters (time-of-flight, energy content of the signals, wavelet packet decomposition-based damage index) for various defects were also investigated.