Ultrasonic discontinuity detection in thin-walled concrete

The ubiquity of concrete components in today's aging infrastructure has led to a pressing need for the development of efficient and effective testing techniques. This paper presents the novel application of ultrasonic techniques such as impact/echo and immersion scanning for discontinuity detection in thin-walled concrete (approximately 60 mm in thickness). Such components are typical in water and wastewater piping networks present in much of the industrialized world. Adaptations to the impact source allowed for an increased frequency response necessary for resonating thinner samples. Utilizing the water saturation present in these concrete samples, ultrasonic energy was propagated through the samples at frequencies up to 360 kHz, often too high for typical concrete specimens. A scanning system was developed capable of locating the different stages of crack propagation including hairline cracking through fracture. The capability of the system to quantify interior aggregate distribution is also demonstrated and discussed. Finally, techniques for practical implementation of this test system are discussed.