Experimental study on waterproof technology of piezoelectric impedance tranducers in concrete

Piezoelectric ceramics (PZT) is one of smart materials, which holds direct and converse piezoelectric effects and can use as impedance transducer for structural health monitoring. However, the PZT transducers must be waterproofed when they are embedded into the concrete structure to monitor the inner stress field since the PZT is a type of moisture absorption material. In this paper, three different waterproof materials, asphalt lacquer, silica gel, and general asphalt are used to overlay the PZT transducers respectively. Subsequently, the real admittances of the inundated PZT transducers are test by the impedance analyzer PV70A. The test results show that the admittance curves of PZT transducer overlaid by asphalt lacquer hardly vary before and after the PZT transducers are inundated into water, which suggests that asphalt lacquer is a fine waterproof material for PZT transducer.