Combined embedded and surface-bonded piezoelectric transducers for monitoring of concrete structures

• Smart aggregates were used for structural health monitoring under cyclic loading.
• Smart aggregates were able to study the overall condition of the structure.
• Localized damage was studied using surface bonded PZTs.
• Combination of smart aggregates and surface bonded PZTs were used for SHM.
• The proposed method can be used for both over all and localized SHM.

Piezoelectric lead zirconate titanate (PZT) transducers are increasingly used for monitoring various engineering structures. PZT transducers are used for monitoring structures based on the electro-mechanical impedance (EMI) for a single PZT and the wave propagation technique for multiple PZTs. In concrete structures, the EMI sensing region is small due to high damping of the concrete. Using the wave propagation technique with high actuation voltage, a larger area can be monitored. The smart aggregates (embedded PZT transducers) can be employed using the wave transmission technique to monitor very large areas with a reasonably low actuation signal. The combination of smart aggregates (using the wave transmission technique) with surface bonded PZTs (using the wave propagation technique) can provide an effective method to study both the local and overall conditions of the structure. In this work, a concrete beam with the dimensions of 220×40×20 cm was cast and nine PZT transducers were embedded or attached on the beam. The PZT readings were correlated with the damage on the structure. Combination of smart aggregates (using the wave transmission technique) with surface bonded PZTs (using the wave propagation technique) for SHM was studied. The results show that this combination provides an effective way to assess both the local and overall conditions of the structure.