© 2017 Proceq SA
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Diameter Measurements on welded Reinforcement Meshes
In most cases a diameter can be measured but the displayed value is far
too large and cannot be used. The only way to determine the diameter is
by an inspection hole.
Scanning on Small Surfaces and Near to Edges
On small areas and near edges you may have to place a cover sheet for
scanning with the probe cart.
For correct cover measurements
the sheet thickness must be set as
Cover Offset value.
In this case no Cover Offset value
must be set
Figure 33:
Scanning near to the edge
4. Profometer Corrosion
4.1 Measuring Principle
4.1.1. Corrosion and Half-cell Potential
Under normal conditions reinforcement steel is protected from corrosion
by a thin, passive film of hydrated iron oxide.
This passive film is decomposed due to the reaction of the concrete with
atmospheric carbon dioxide (CO
2
, carbonation), or by the penetration of
substances aggressive to steel, in particular chlorides from de-icing salt
or salt water.
At the anode ferrous ions (Fe++) are dissolved and electrons are set free.
These electrons drift through the steel to the cathode, where they form
hydroxide (OH-) with the generally available water and oxygen. This prin-
ciple creates a potential difference that can be measured by the half-cell
method.
Figure 34:
Principle of steel corrosion in concrete with oxygen availability
