Fully Contactless Ultrasonic System to Characterized Concrete Structure With Guided Wave Approach and Energy Attenuation

Ultrasonic techniques provide an effective non-destructive evaluation (NDE) method to monitor concrete structures, but the need to perform rapid and accurate assessment requires evaluation of hundreds, or even thousands, of measurement data. Use of a fully contactless ultrasonic system can save time and labor through rapid implementation and can enable automated and controlled data acquisition, for example through robotic scanning. Here we describe a fully contactless ultrasonic system composed of an electrostatic transducer sender and MEMS sensor receiver. The developed contactless sensors, controlled scanning system with mobile apparatus and employed signal processing schemes are described. The system is demonstrated through tests on concrete slabs for two applications in concrete: detecting near-surface delaminations using a guided wave approach and characterizing the level of microcracked concrete using a surface wave energy attenuation approach. In the first case, the concrete delaminations are interpreted in terms of guided plate wave (Lamb wave) theory. In the second case, energy loss (attenuation) is used to indicate the level of distributed cracks in concrete. In both cases the ultrasonic system shows good results and consistent data.

References
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