Comparative Study of Rebound Hammer, Nitto Hammer, and Pullout Tests to Estimate Concrete In-Place Strength by Using Random Sampling Analysis

The use of nondestructive testing (NDT) techniques to estimate concrete in-place strength has been broadly studied, with proof of their usefulness in complementing destructive testing (DT). However, the use of DT techniques still dominates. The main objective of this investigation was to compare the performance of three NDT techniques—the rebound hammer, Nitto hammer, and pullout tests—to determine in-place strength. NDT-versus-strength correlation curves were fit to data measured from thick concrete slabs. Strength was measured from cast-in-place cylinders. Analyses of NDT sensitivity, uncertainty, and variability are presented. A new parameter to quantify the performance of the NDT techniques is proposed. This parameter is the limit error between the measured and estimated strengths, which combine uncertainty and variability analyses. The analysis shows that the least limit error for predicting in-place strength was achieved by the rebound hammer test when one testing location was considered or by the pullout test for two or more testing locations.