Monitoring the strength development in concrete by EMI sensing technique

For any new nondestructive evaluation (NDE) technique, prior to full commercialization and real field application, rigorous studies are needed to address its practicality and reproducibility of the results under nominally the same conditions. Recently, the applicability of electro-mechanical impedance (EMI) sensing technique has been extended to monitoring of concrete curing and strength gain. Experimental investigations of this relatively new NDE technique for damage detection in structures have been successfully demonstrated by many researchers. The objective of the present study is to further develop the application of the EMI sensing technique for in situ monitoring of concrete using the low cost piezoceramic (PZT) patches. In this investigation, resonant frequencies of the surface bonded PZT patches were tracked using an impedance analyzer by sweeping the frequency within the range of 100-400 kHz. The experimental results verify the practicality of the EMI sensing technique for monitoring the strength development in concrete. Using an established empirical relationship, the relative strength gain of concrete can be predicted by monitoring the resonant frequency shift. The quantitative approach based on the statistics metrics such as RMSD, MAPD and CCD to compare the EMI spectra is also presented. (C) 2010 Elsevier Ltd. All rights reserved.