Civil Engineering Reference
In-Depth Information
Impressed current cathodic protection is frequently found to be the most
cost-effective solution on reinforced concrete structures with chloride-
induced corrosion with a long required life (over 10 years). However it is
also widely used in other situations including carbonated structures and
where any corrosion damage is unacceptable.
Another advantage of applying impressed current cathodic protection
is that patch repairing can be made easier. As the corrosion protection is
provided by the cathodic protection, cutting out and patching is easier as
all chloride-contaminated (or carbonated) concrete does not have to be
removed from behind the corroding reinforcement, as shown in
Figure 4.5.
There are now well-proven national and international standards for
supply, installation, monitoring and control of impressed current cathodic
protection. These include the European Standard BS EN 12696 (2000),
NACE standard RP 0290 (2000), and Australian/New Zealand standard AS
2832.5 (2002).
The key advantages of impressed current cathodic protection are:
•
It controls corrosion in all areas where anodes are applied.
•
It stops the 'ring anode' or 'incipient anode' effect.
•
It simplifies repairs as there is no need to remove chloride-contaminated
concrete. This can avoid requirements to prop the structure during
repairs.
•
There are good, well-recognised international standards for applying
the technique.
Concrete removal beyond the
corroded area is not required
for electrochemical treatment
Feathered edges and
poor preparation allow
breakaway at edges and
poor keying
Squared edges cutting behind
the bar and removal beyond the
corroded area restores passivity
and removes contamination
such as impressed current cathodic protection.
