NDT 4 Recommendation for in situ concrete strength determination by combined non-destructive methods

The aim of the Recommendation is to provide guidance on the combination of different methods of non-destructive testing (NDT) to increase the accuracy of the estimation of the in situ compressive strength of concrete. In particular, detailed information is provided for the combination of in situ measurements based on longitudinal pulse velocity and on rebound hammer index measurements, the best known and most widely used of such combinations [ 1-12].