Impact Products Digital Concrete Test Hammer CN652 - Manual (Page 6)

The DIGI-SCHMIDT 2000 concrete test hammer comprises the actual concrete
test hammer and the display unit.
Both components belong together and are calibrated as one unit.
The impact bolt of the concrete test hammer strikes the surface of the concrete
with a defined force. After the impact, a metal body, the so-called hammer (see
pos. 14 in Fig. 6.2, page 16), rebounds. The rebound distance is measured by a
sensor and passed on to the display unit as an electrical signal. The signal
converted by the electronics is shown on the display unit as rebound value R
and, if necessary, displayed together with the corresponding compressive
strength of the concrete, fck.
There is a specific relationship between the rebound value R and the hardness
and strength of the concrete. The following factors must be taken into account
when ascertaining rebound values R:
- Impact direction: horizontal, vertically upwards or downwards
- Age of the concrete
- Size and shape of the comparison sample (cube, cylinder)
Model ND can be used for testing:
- Concrete items 100 mm or more in thickness
- Concrete with a maximum particle size < 32 mm
Model LD can be used for testing:
- Items with small dimensions (e.g. thin-walled items with a thickness from 50 to
100 mm)
With Model LD, it may be necessary to clamp the items to be tested
prior to measurement in order to prevent the material from deflecting.
- Items made from artificial stone which are sensitive to impacts
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