Non-destructive Testing (NDT) of Concrete in Structures

Abstract

Non-Destructive Testing (NDT) methods are used to determine the condition and quality of concrete or to locate objects embedded in concrete, without damaging or destroying the concrete. Some NDT methods may be used to identify the location and development of cracks and voids which are not visible at the concrete surface but which may affect the structural or durability performance of concrete. Due to the specialised nature of NDT methods and the specific equipment required for each method, operators must be well trained and familiar with all factors affecting the test conditions and the readings or responses obtained. Also, the results must be properly evaluated and interpreted by experienced personnel who are familiar with the particular NDT technique. Each NDT method has its advantages and limitations for certain assignments, and none can be used alone to give an effective and unambiguous diagnosis. It is important to avoid any negative influences such as weather conditions, and to be aware of the limits of the technique in response to various objects. Some NDT methods are comparative and rely on a control or reference sample such as a defect-free item or a series of test cylinders to establish the base response. This Technical Note provides an overview of the different NDT methods available and nominates suitable applications for their use1,2,3 .