Use a grinding stone to smoothen the test surface
Perform a few test impacts with the rebound hammer on this smooth, hard surface before taking any measurements which you are going to evaluate. Perform a consistency check on the test anvil
Position the hammer perpendicular to and against the test surface. Push the concrete test hammer adainst the surface at a moderate spped until the impact is triggered. Bes aware that the plunger generates a recoil when it deploys.