The non-destructive testing of concrete

Abstract

Summary: A method is described which has been used to determine the velocity of longitudinal waves in concrete specimens by measuring the time taken for an ultrasonic pulse to travel through a known length of concrete. Results are given which illustrate the use of the method for studying the variations occurring among laboratory specimens. The value of the longitudinal wave velocity as an index of concrete quality is discussed, with reference to tests made on a variety of specimens subsequently subjected to compressive and flexural strength tests and density analysis. Deterioration of concrete quality due to freezing and thawing can be detected before superficial damage occurs. The Poisson's ratio of several types of concrete has been measured and values from 0·16 to 0·31 obtained depending mainly upon the type of aggregate.