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Schmidt Concrete Test Hammer

Schmidt Concrete Test Hammer

Surface Hardness and Penetration Resistance


BS1881: Part 202 ;ASTM C805
The concrete hammer is a hand held instrument used for testing the quality of hardened concrete in a structure.
On new structures, once the concrete has hardened, the instrument can be used to give an indication of the gain in concrete strength.
On existing structures, it can be used to gain an estimate of the uniformity of the concrete.


The instrument works on the principle that the rebound of an elastic mass impacting on a surface is a function of the hardness of the surface itself. Hence the harder the surface, the greater is the rebound distance.
The test sequence consists of:
1. prior to using the hammer, the surface of the concrete is first abraded with the carborundum stone to remove surface irregularities.
2. the hammer is then pushed firmly against the concrete until the the trigger button is automatically released
3. hand pressure is then reduced, to allow the plunger to fully emerge from the instrument.
4. extra hand pressure is then applied to push the plunger back into the instrument, compressing the internal spring to a point where the trigger mechanism over-rides and causes the impact force to be applied to the surface.
5. still applying hand pressure, the push button is pressed to lock the plunger in place, retaining the reading on the graduated scale.
6. the strength corresponding to the reading on the scale is then noted.
7. if concrete test cubes from the structure are available, then using the hammer on these will allow a more accurate answer to be established.

Measures concrete strengths of:
10 to 70 N/mm (100 to 700 kgf/cm)
Supplied in a carrying case complete with carborundum stone.
Total Weight 1.7kg.