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5.3 MEASURING CELL-TO-CELL RATHER THAN CELL-TO-BAR
In some instances it will not be possible to make a direct connection to a reinforcing bar. In this situation it
is common practice to use two half-cell probes connected to the inputs of the Half-Cell Meter. One probe is
fixed in position on the concrete surface and the other probe is moved over the surface. In this way the
surface can be 'mapped'.
Using this method, the absolute value of the reinforcing bar to concrete half-cell will not be measurable,
however changes from one point on the surface to the next can be measured and interpreted.
6 HALF-CELL PROBES
Two types of half-cell probe are available for your Half-Cell Meter. The probes can be easily identified by
colour:
•
Copper-Copper Sulphate (Cu-CuSO
•
Silver-Silver Chloride (Ag-AgCl): Blue
6.1 WETTING YOUR PROBE
For your probe to function properly the ceramic sensing end (the electrode) must be wet. To get a good wet
electrode, just place the electrode in tap water for two to three minutes; usually this will be sufficient to keep
the sensor going all day. Keeping the plastic end cap on the sensor when it is not being used will also help
to keep the electrode wet. During periods of extended storage, place a small amount of water in the end
cap before pushing the cap onto the probe.
20
): Yellow
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