NDT method of impedance spectroscopy was used to characterize concreteslab specimens without and with contact graphite compound coating. Differences intan δ (f), Im Z(f) and Re Z(f) spectra for dry specimens were observed. Furthermore,based on the predominant loss type, the material quality was characterized. Ourmeasurements confirmed the reproducibility of this method. Furthermore, theinfluence of the concrete specimen composition on their electric parameters wasassessed.