Evaluation of Concrete Strength by Combined NDT Techniques: Practice, Possibilities and Recommendations

This chapter presents a summarized state of the art of the available methods (SonReb and new methodologies) for the combination of NDT measurements. This synthesis can be helpful for selecting NDT methods for the combination. The chapter also discusses in which condition it is convenient or not to apply the combination of methods. Several possible approaches are detailed in a synthetic way. SonReb method is the most popular method for combining NDT methods, likely UPV and rebound hammer. The use of more than two NDT techniques with the objective of improving the evaluation is presented. This approach of combination can be interesting for example if moisture content varies in the tested concrete or if the quality of techniques is equivalent and if they are complementary. The results of the literature have been presented and discussed for a possible use in the RILEM recommendations. As a first result and without additional computational work, the use of the different approaches is discussed regarding the test result precision of, the TRP, and the magnitude of the final conversion model error.