This is intended for non-destructive testing of the quality of concrete in finished structures.

In testing, the rebound number is measured, which is dependent on the strength of the mortar (concrete with coarse particles) close to the surface. Since the strength of the mortar as a rule determines the strength of the concrete, the rebound number gives an indication for the strength of the concrete. The results obtained are ±15% of the actual compressive strength. As the test does not destroy the specimen, the curing process continuing after setting of concrete the be followed up accurately.