Schmidt/Rebound Hammer test is a Non-destructive testing method of concrete which provide a convenient and rapid indication of the compressive strength of the concrete. The rebound hammer is also called as Schmidt hammer that consist of a spring controlled mass that slides on a plunger within a tubular housing. When the plunger of rebound hammer is pressed against the surface of concrete, a spring controlled mass with a constant energy is made to hit concrete surface to rebound back. The extent of rebound, which is a measure of surface hardness, is measured on a graduated scale. This measured value is designated as Rebound Number (rebound index). A concrete with low strength and low stiffness will absorb more energy to yield in a lower rebound value. The rebound hammer test have the following objectives:

1. Determine the compressive strength of the concrete by relating the rebound index and the compressive strength
2. Assess the uniformity of the concrete
3. Assess the quality of the concrete based on the standard specifications
4. Relate one concrete element with other in terms of quality