Ultrasonic pulse method for detecting internal defects and cracks in concrete structures : 52152 Luo, Q. Non-Destructive Testing in Civil Engineering, Liverpool (United Kingdom), 14–16 Apr. 1993. Vol. 2, pp. 531–550. Edited by J.H. Bungey. The British Institute of NDT (1993)

Abstract

The ultrasonic pulse method has been used for many years for the detection of internal defects in concrete structures. There are, however, only quantitative differences between the acoustic parameters (pulse velocity, amplitude of the wave) of regions containing defects and those without defects when using transmission measurements. Methods of judgment whether internal defects exist or not based on the data obtained from the different measuring points thus becomes a worthwhile topic to explore. The Author has proposed a method based on the theory of mathematical statistics - the Probability Method. This method has been verified to be valid through practice. The shortcomings of empiricism in judging defects have been eliminated by using this method and automation in judgment and analysis work is also possible. Cracks are often found in concrete structures for a variety of reasons. For shallow cracks, the crack depths can be measured by general ultrasonic pulse methods. For deep cracks with depths more than several metres, the Author has developed an opposite drilling measurement technique to measure their depths. This is based on determining the existence of the cracks through the amplitude changes of the received wave. After the cracks are grouted, the method has also been used to investigate the grouting effectiveness. (A) For the covering abstract see IRRD 861706.