The W-M-250 Manual Test Hammer is the traditional instrument used for the non-destructive testing of hardened concrete. This easy-to-use instrument provides a quick and simple test for obtaining an immediate indication of concrete strength in various parts of a structure. The minimum verifiable strength is 1400 PSI (10 MPa) to approximately 9000 PSI (62 MPa). All concrete test hammers measure the surface hardness of the material they are testing; this is then correlated to concrete compressive strength.
The manual concrete test hammer, aka rebound hammer, schmidt hammer, swiss hammer, sclerometer, is the most widely used non destructive instrument for compressive strength determination. However, it typically has the largest coefficient of variation; therefore its result should be verified with another non destructive test such as the V-Meter MK III.
Typical Correlation Charts for James Instruments Rebound Hammer