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© 2012 by Proceq SA
7.2
Reading the display screen
Object number
Mean value / measured values.
Minimum value / maximum value.
Table position: Value stored at that position.
Actual resistivity measurement: Proportion of current flow
through the concrete relative to the nominal current.
The position in which a measured value can be stored in the
table can be selected with the cursor keys.
Fig 7.2 Resistivity measurement screen
7.3
Measuring with the Wenner Probe
In order to obtain a reliable reading, it is necessary to have a good electrical contact between the
foam pads of the resistivity probe and the concrete surface.
As far as possible, reinforcement bars should not be directly beneath the probe and should not run
parallel to the probe. The recommended procedure is to measure diagonally to the rebars. (e.g RILEM
TC154-EMC: ELECTROCHEMICAL TECHNIQUES FOR MEASURING METALLIC CORROSION rec-
ommends making 5 readings from the same location moving the probe a few mm between each
measurement and taking a median from the 5 values.).
The well-moistened probe should be pressed lightly against the surface of the concrete until the
reading is stable.
The “Current” field (See Fig 7.2) monitors the current flow through the concrete. If there is a bad con-
tact between the electrodes and the concrete or if the conductivity of the concrete is small, the flow
of the current will be reduced. This gives an indication as to the reliability of the reading obtained.
50% to 100%
The reading is reliable.
20% to 50%
“Value not exact” will be displayed on the screen.
0% to 20%
The resistance is >99k
Ω
cm or the contact is very poor.
Once the reading is stable it can be saved by pressing the STORE button. It will be saved in a table
in the position indicated on the display (e.g “G7” in Fig 7.2). The table has a maximum size of 16x16
cells. The position in the table where the measurement is stored must be selected manually on the
screen (Fig 7.2).
Use the
←→
buttons to select a letter from A to P.
Use the
↑↓
buttons to select a number from 1 to 16.
Fig 7.3 Table for resistivity measurements.
