A Regression Model Predicting The Compressive Strength Of Concrete By Means Of Non Destructive, Acoustic Measures

The standard method of evaluating the quality of concrete in buildings or structures is to test specimens cast simultaneously for compressive, flexural and tensile strengths. The main disadvantages are that results are not obtained immediately; that concrete in specimens may differ from that in the actual structure as a result of different curing and compaction conditions; and that strength properties of a concrete specimen depend on its size and shape. Although there can be no direct measurement of the strength properties of structural concrete for a reason that strength determination involves destructive stresses, several non- destructive methods of assessment have been developed. These depend on the fact that certain physical properties of concrete can be related to strength and can be measured by non-destructive methods. Such properties include hardness, resistance to penetration by projectiles, rebound capacity and ability to transmit ultrasonic pulses and X- and Y-rays. These non-destructive methods may be categorized as penetration tests, rebound tests, pull-out techniques, dynamic tests, radioactive tests, and maturity concept. According to Mehta 1 , the development of nondestructive test (NDT) methods for concrete has progressed at a slower pace compared to the development of NDT for steel structures because concrete is inherently more difficult material to test than steel. Concrete is highly heterogeneous on a macroscopic scale. It is electrically non conductive but usually contains significant amount of steel reinforcement. Thus it has not been an easy task to transfer the NDT technology developed for steel to the inspection of concrete.