Wave attenuation measurement technique for nondestructive evaluation of concrete

Nondestructive testing (NDT) that uses ultrasonic waves is a reliable experimental technique for characterisation of materials in existing concrete structures and for safety evaluations of these structures. The wave velocity is related to the stiffness of material and the wave attenuation can be used to evaluate damaged concrete structures. This paper proposes an experimental technique to quantitatively measure the wave attenuation using contact ultrasonic transducer for NDT. The proposed technique is subject to interference as a result of the transducer-coupling condition. Unbiased attenuation can be obtained by self-compensating the signals measured in a lead–zirconate–titanate ceramic material inserted between a conventional transducer and a sample. The reproducibility and relevancy of the proposed technique are demonstrated using examples of the technique applied to cement paste and concrete. Also, the relevancy of the attenuation measurements for damage evaluation of cement-based material is demonstrated based on a theoretical attenuation model.