Spectral tomography of concrete structures based on impact echo depth spectra

This paper proposes a spectral tomography for nondestructive test of concrete structures based on the spectral data of impact echo test. Firstly, a mesh is drawn on the surface of the concrete. Then, impact echo tests are performed at the grids. The recorded signals are processed to obtain the spectra of the concrete. The spectra are further transformed into the depth spectra and assembled into 3D volume data. Finally, spectral tomography is applied to the volume data to construct the image of the concrete structure for arbitrary cross-sections. Both numerical and experimental tests are performed to verify the effectiveness and reliability of the proposed imaging method. It is seen that the spectral tomography can be used to show the internal cracks in the concrete specimens successfully.

► Spectral tomography is developed to detect the defects in concrete structures.
► The spectral tomogram is constructed based on the impact echo spectra.
► Inspectors can view arbitrary cross-sections of the concrete structure.
► The tomogram can be used to estimate the size, depth, and orientation of a crack.