Civil Engineering Reference
In-Depth Information
10 Operate the system for 12 months and supply a 12-month monitoring
report.
11 Hand over system to client who appoints a suitably qualified and trained
engineer to continue monitoring the system (this may be the client's
own engineer, the contractor's engineer or an independent cathodic
protection engineer).
Advantages and limitations of impressed current cathodic
protection
The main reason for choosing to use an impressed current cathodic protection
system as part of the repair and rehabilitation strategy for a structure is that
it controls corrosion across the whole area where anodes are installed.
When carrying out repairs to corrosion-damaged reinforced concrete it
is important to be aware of the 'ring anode' or 'incipient anode' effect. This
is illustrated in
Figure 4.3,
4.4a
and
4.4b.
The problem is that by repairing
the corroding anode, we generate new anodes around the repair. This is
especially prevalent in chloride-contaminated concrete where the higher
moisture levels and the chloride content lower the electrical resistance of
the corrosion cell and allow greater separation between anode and cathode.
BEFORE
AFTER
Concrete
Concrete
Patch
of the repair by the formation of a new cathode in the patch repair (from Broomfield
2007).
