Figure 3. Recommended installation mounted on the reinforcement net. The CorroWatch probe is mounted in combination with an ERE-20 reference- electrode (blue cable).
Position It is recommended to install the CorroWatch probe (Figure 1) in the concrete cover between the concrete surface and the outer reinforcement layer. To ensure correct function it is extremely important that great care is taken when mounting the CorroWatch probe. It is important that the position of the probe does not change during casting. This is ensured in the best way by e.g. mounting the probe on at least two reinforcement bars (Figure 3).
Anodes
Cathodes
Figure 2. CorroWatch probe structure. The black cable is the reinforcement connection cable.
Surveillance and early warning system
Structure
The CorroWatch multiprobe is composed of: 4 anodes, 1 cathode, 1 reinforcement connection and an internal temperature sensor. The 4 anodes are placed in a joint ring in varying but well known distance to the ring’s bottom. The cathode is placed in the ring’s periphery.
Installation
To obtain optimum evaluation possibilities, we recommend the CorroWatch probe be mounted in combination with an ERE-20 reference-electrode.
The cables from the CorroWatch probe and the ERE-20 reference-electrode are joined and conducted to the concrete surface. To protect against casting damage, it might be advantageous to conduct the cables in conduits.
Colour codes in cable
In the standard edition the following colour codes are used in the black CorroWatch probe cable (see Figure 2): Red Cathode (net) Brown Highest anode Blue Second highest anode Green Second lowest anode Yellow Lowest anode White Reinforcement connection Pink Grey Temperature sensor
Mounting - step by step
1. Control on receipt Check that the CorroWatch probe has not been damaged during shipment. The 4 anodes shall be placed as shown in Figure 1 and they must not be loose or corroded. The cable must show no signs of damage e.g. from squeezing.
2. Mounting To avoid rust formation on the anodes, the mounting of the CorroWatch probe should be performed as close to the casting time as possible. By use of plastic strips, the Cor- roWatch probe is mounted on a stable base, e.g. the rein- forcement net. The anodes must face the future concrete surface and they must be placed parallel to this. It is impor- tant that the sensor is firmly mounted, so that displacement does not happen during casting. The anodes and the cath- ode must not be in any metal contact with the reinforce- ment. To achieve a satisfactory recasting we recommend suitable distance be kept to other embedded parts.
For direct connection to reinforcement use the black single wire from the body of the probe.
Close to the CorroWatch probe an ERE-20 reference-elec- trode is mounted.
3. Measuring The placing of the CorroWatch probe should be illustrated in a draft with measurements that are detectable after cast- ing. Furthermore, the distance (perpendicular to reinforce- ment and anode) from the outermost reinforcement to the outermost anode should be measured and noted (Figure 2).
4. Marking When several CorroWatch probes are mounted it is impor- tant to mark the individual cables in a way that leaves no doubt as to where each cable pertains.
5. Cabling The best way to protect the cables against damages dur- ing casting is by conducting them to the concrete surface through a conduit.
6. Degreasing All electrodes should be degreased with ethanol or acetone before casting is initiated.
7. Casting Great care should be taken when using immersion vibrator etc. close to the CorroWatch probe during casting. Marking should be done on the concrete forms.
8. Remounting After casting and form removal the finishing cabling and mounting are carried out in the terminal board in a mul- tiplexer or data logger. When choosing materials for this work it is important to consider risks of moisture problems or vandalism. Cable identification is done by marking and sketching drawings. Before closing the multiplexer we rec- ommend a bag of dehydrating agent to be placed inside it.
Specifications The standard CorroWatch probe is supplied with specifica- tions as follows:
Dimension:
Body Ø85 mm
Height 55 mm
Width 165 mm
Cable: Screened 8-conductor Length 5 m (standard) Colour Black
Anodes: Length 60 mm Diameter Ø12 mm
Weight: Approx. 0,5 kg
Cathode: Red cable
Rebar’s: White cable, if connected
Anode 1 Brown cable (about 55 mm high)
Anode 2 Blue cable (about 50 mm high)
Anode 3 Green cable (about 45 mm high)
Anode 4 Yellow cable (about 40 mm high)
