Ultrasonic testing of concrete using split spectrum processing

In this paper, we present results for nondestructive testing of concrete using ultrasonic pulse echo techniques to detect and localize discontinuities which may cause critical infrastructure problems. Concrete is a highly attenuating medium and only limited penetration can be obtained using high frequency ultrasonic signals. However, even when sufficient penetration is achieved, significant background noise due to randomly distributed scatterers can corrupt the echoes from discontinuities. We apply split spectrum processing (SSP) technique to distinguish flaw signals from the background microstructure noise corresponding to complex, dispersive and nonhomogeneous reflectors. The experimental results are obtained for different types of concrete, using transducers with center frequencies of up to 1 MHz. Experimental data from concrete samples such as mortar, with and without discontinuities, and other concrete specimens using transducers with 0.25, 0.5, and 1 MHz center frequencies demonstrate SSPs noise reduction and discontinuity detection capabilities.