Paper Title
Correlation between Rebound Index and Destructive Compressions Testing for Concretes: A 33 Years of Experience with Schmidt Rebound Hammer

Original Schmidt curve is provided by the producers along with the hammer and compressive strength of concrete member can be estimated by empirical relationships between rebound index and compressive strength. Empirical formulae based on laboratory tests can be used only within their limits of application. The expected error of the strength estimation by rebound index under general service circumstances is about 30 to 40%. Present research paper gives a summary of experiences with the rebound index in the last more than 33 years. Application of this technique on different concrete grade cubes, showing that several phenomena strongly affect the mechanical and physical behavior, W/C ratio, type of cement. Strength estimates may differ as much as 70%, if these parameters are not taken into account. After review the 33 years of experience by the several researchers, we conclude that the no unique relationship between the Schmidt rebound index and compressive strength. Keywords - Schmidt Rebound Hammer, Surface Hardness, Rebound Index, Strength Estimation