Abstract: Disclosed are non-destructive evaluation systems and method thereof for detecting delamination, overlay debonding, spalling and detecting and differentiating between sound and delaminated patches in concrete structures. The non-destructive evaluation method for detecting delamination in concrete structures includes obtaining a plurality of acoustic waves, storing the plurality of acoustic waves, calculating a short-term Fourier transform (STFT) spectrum for each of the plurality of acoustic waves, wherein each STFT spectrum comprises a plurality of window discrete Fourier transforms, and detecting the delamination based on the STFT spectrum.