Thermography and ultrasound for characterizing subsurface defects in concrete

Abstract

A combination of non destructive testing (NDT) techniques is applied for subsurface damage inspection. Thermography and ultrasound are used compli-mentarily to detect and characterize near surface cracking. In this paper, specimens with subsurface cracks, are scanned by an infrared camera in order to indicate the position of the cracked area. For cases of small and thin cracks the cooling off curves over a specifid time span are examined in order to identify the damage areas more reliably. At the specific position indicated by thermography, ultrasonic sensors are placed in order to make a more detailed assessment for the depth of the crack. Although there is no visual sign of damage, ultrasonic waves are influenced in terms of velocity and attenuation. © RILEM 2013.