Report on Nondestructive Test Methods for Evaluation of Concrete in Structures

Description

Nondestructive testing (NDT) methods are used to deter-mine concrete properties and to evaluate the condition of concrete in deep foundations, bridges, buildings, pavements, dams, and other concrete construction. For this report, NDT is defined as generally noninvasive, with the excep-tion of transport property tests, which may cause easily-repaired surface damage. While coring and load testing may be considered nondestructive, they are excluded from this report. Refer to ACI 437R for more information about strength evaluation of existing concrete buildings.

NDT methods are applied to concrete construction for four primary reasons:1. Quality control of new construction2. Troubleshooting problems with new and old construction3. Condition evaluation of older concrete for rehabilitation purposes4. Quality assurance of concrete repairs NDT technologies are evolving and research continues to enhance existing methods and develop new methods. The report is intended to provide an overview of the principles of various NDT methods practiced and to summarize their applications and limitations. Emphasis is placed on methods that have been applied to measure physical properties other than the strength of concrete in structures, to detect flaws or discontinuities, and to provide data for condition evaluation.

Traditionally, quality assurance of concrete construc-tion has been performed largely by visual inspection of the construction process and by sampling the concrete to perform standard tests on fresh and hardened specimens. This approach does not provide data on the in-place prop-erties of concrete. NDT methods offer the advantage of providing information on the in-place properties of hardened concrete, such as the elastic constants, density, resistivity, moisture content, and fluid transport characteristics.