Visualised NDT for concrete cracking by SiGMA-AE and SIBIE

Visualised techniques of non-destructive testing (NDT) are investigated for concrete cracking. Acoustic emission (AE) techniques have been extensively studied and applied to concrete and concrete structures. Currently, source kinematics of crack location, crack type and orientation can be quantitatively identified by the SiGMA procedure of AE. Thus, AE source characteristics in diagonal-shear failure are visually clarified. The impact-echo method is developed for NDT of defects in concrete. Resonance frequencies are applied to estimate the presence and the depth of defects in concrete. Because it is not easy to identify particular peak frequencies only responsible for the presence of defects, SIBIE procedure is developed. The procedure is applied to an ultrasonic test of an artificial surface-crack in concrete. It is shown that the crack-depth is clearly visualised, even in the case that the crack is partially filled with water.