Coated Surfaces; Pre-Moistening - Proceq PM8500 User Manual

Profometer corrosion

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4.1.11 Coated surfaces

It is not possible to make a measurement through an electrically isolating coating (e.g. an

epoxy resin coating, sealing sheets or asphalt layers.)

It is possible to make a measurement through thin dispersion coatings, that are often used, for

example on the walls and ceiling of underground car parks, however this can cause a small

shift of the potentials.

It is always necessary to check whether a measurement can be made through a coating. To

do this, potentials should be measured at a few locations:

in the first place through the coating and

with the coating removed

If possible, areas with largely varying potentials should be chosen. If there is no alteration of

the potential, or if a shift of the potential can be compensated by a correction (e.g., ρV = ± 50

mV), then a measurement can be made directly on the coating. If not, then the coating must

be removed before making the measurement.

The contact between the pore solution of the concrete and the probe can be impaired by a

dried out concrete skin. This can greatly increase the electrical resistivity of the concrete.

It is therefore recommended to moisten the surface approximately 10 to 20 minutes before

carrying out the measurement. If this is not possible, it must be ensured that the sponge on

25. September 2023

Figure 15 : PM8500 Four Wheel Electrode. Wheel spacing set up

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