Embedded piezoelectric pitch-catch sensing-based NDT techniques for concrete strength evaluation

Recently, novel methods using piezoelectric materials to monitor the strength development of concrete during curing process have been reported. However, these methods showed some limitations to obtain an absolute concrete strength in realworld. In order to estimate the absolute strength of the concrete, the concrete strength monitoring method using embedded pitch-catched guided-wave propagation is proposed in this study. Because the wave signals are varied by the change of mechanical properties of structure, the strength of the concrete can be estimated. Moreover, to obtain the absolute strength of the concrete, specific strength equations are derived using the features extracted from the wave signal variations according to the strength development of the concrete. To verify the effectiveness of the proposed approach, a series of experimental studies using miscellaneous concrete specimens have been carried out. The guided-wave signal was measured by embedded piezoelectric sensors using a pitch-catch method. The propagation velocity was extracted from the each signal, and the strength estimation equation was derived from the relationship between velocity and measured compressive strength. Finally, further research issues will be discussed for real-world implementation of the proposed approach.