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version 1.2_en
CM method
Another common method of determining the moisture
of the bottom layer
of
screed
is the CM method. The accuracy of the CM method depends on
various parameters and is not suited for a comparison with the humimeter
GF2 resp. for material calibration. In the following chart of producers of CM
devices you can find comparative values of measurements in drying chamber
in weight% to CM% for some concrete types. Please find comparative values
for other concrete types in the user manual of your CM device.
CM calibration curve
The CM floor screed calibration curve is a conversion from water content into
CM %. The measurement values of this calibration curve are guidance values
and do not replace the CM method. However, via the non-destructive
measuring process of the GF2 the measurement is simplified. Subsequently
a CM measurement according to the norm is recommended!
cement
screed
weight %
1.8
2.2
2.7
3.2
3.6
4.1
4.5
5.0
CM %
0.7
1.0
1.4
1.8
2.1
2.5
2.9
3.2
anhydrite
floor
weight %
0.1
0.3
0.6
1.0
1.4
1.8
2.2
2.5
CM %
0.1
0.3
0.6
1.0
1.4
1.8
2.2
2.5
concrete
B15,B25,B35
weight %
1.3
1.9
2.5
3.2
3.8
4.4
5.0
CM %
0.3
0.8
1.3
1.7
2.2
2.7
3.2
If your CM device shows a cement screed moisture value of 1.8 CM%, this
value corresponds to 3.2 weight% corresponding to the norm method in the
drying chamber.
Drywall
For measuring drywall, press the humimeter GF2 with its
full surface and a pressure of approx. 4 kg on the outside
of the drywall. There must not be any metal or anything
similar in an area of
50mm
behind the drywall.
