Ultrasonic Characterization of Damage in Concrete

Ultrasonic non-destructive evaluation is an essential component of con- dition assessment of concrete. Conventionally, the use of ultrasonics is limited to the study of velocity of sound through concrete. The velocity is qualitatively linked to the condition of the concrete in service. However, sophistication in signal pro- cessing has led to the development of better ultrasonic techniques that can give some quantitative estimates of the damage. This paper describes the use of the transmitted ultrasonic energy to estimate the level of damage in concrete under uniaxial compression. The experimental set up was designed to collect ultrasonic signals between transducers at opposite ends of a concrete cube that was loaded in compression. A specially designed software program allowed real time analy- sis of the signal - including calculation of transmitted energy, obtaining FFT, etc. The methodology adopted in the study was able to differentiate the behaviour of ordinary and high strength concrete in compression.