Quantitative Evaluation of Surface Crack and Internal Defect in Concrete Member by Ultrasonic Spectroscopy

Abstract

The lack of the durability in concrete structures is reported widely as serious problems. To keep the safety of structures and to confirm the long service life, the development of effective non-destructive evaluation method for defects is in urgent demand. In this paper, an evaluation method for cracks and internal planar defects in concrete members is studied by using the ultrasonic spectroscopy. Spectral responses obtained by using sweep mode input of a function generator are applied to evaluate these cracks and defects. In experiments, artificial surface cracks normal to the axis and planar defects embedded parallel to the surface in concrete members are investigated quantitatively. Two-dimensional resonance analysis of the members with these defects is performed by using the Boundary Element Method (BEM). These results show that the present method is promising as quantitative evaluation method of the cracks and defects in concrete members.