Effect of the Compressive Strength of Concrete and the Size of Tested Specimens on the Compressive Strength of Concrete Obtained from Non-Destructive Test Using Rebound Hammer

Abstract

This objective of this research was to study the effect of the compressive strength of concrete and the size of specimens on the compressive strength of concrete obtained from non-destructive using rebound hammer. The actual compressive strength of concrete specimens had 3 levels; i.e. 235, 321, and 398 ksc, according to ASTM C192 standard. The concrete specimens were tested by rebound hammer with 3 different directions; i.e. -90º, 0º and +90º. Five different sizes of concrete samples were investigated: (a) 15 cm cube; (b) 22.5x22.5x15 cm prism; (c) 30x30x15cm prism; (d) Ø15x20 cm cylinder; and (e) and Ø15x30 cm cylinder. All concrete specimens were cured in water at 28 days. It was found from the study that the wider and the thicker of concrete specimens led to the higher compressive strength obtained from rebound hammer test. Furthermore, it was found that those cylindrical specimens gave the higher compressive strength from rebound hammer than those cube specimens, because the cylindrical specimens were thicker so that the higher rebound number would be obtained.