Quantitative study of electromagnetic wave characteristic values for mortar's crack

Horizontal 4 mm-thickness cracks with various depth in different cement mortar specimens simulate respectively various inner micro-defects. GPR antenna of 1.0 GHz and 2.3 GHz central frequency scans respectively the inner-cracked specimens and non-crack one. Electromagnetic waveform characteristic, travel time and correlation of encoded ground penetrating radar reflection signals are quantitatively evaluated. The electromagnetic waveform and its travel time from 2.3 GHz antenna appear distinct reflection characteristic at the interface of inner crack; while only transmission of electromagnetic wave is observed when 1.0 GHz antenna employed. The correlation coefficient of encoded signals, is an available parameter to depict quantitatively inner crack, based on which a brief method to visualize inner crack is promoted within average erroneous percentage of 6% in shallow crack when scanned by 2.3 GHz antenna.