The document discusses cathodic protection systems for repairing reinforced concrete structures. It describes two main types of cathodic protection - sacrificial anode cathodic protection (SACP) and impressed current cathodic protection (ICCP). ICCP uses an external electrical current to protect steel reinforcement from corrosion, while SACP uses sacrificial metal anodes. The document provides details on ICCP components and advantages such as flexibility and minimal concrete removal. It also notes disadvantages like requiring electrical power and specialist monitoring. Sample case histories describe using ICCP to repair bridge piers and highway structures by dividing them into protection zones.

1. The selection and use of cathodic protection systems for the repair
of reinforced concrete structures
ABSTRACK
Cathodic protection (CP) is an electrochemical repair technique that has increasingly been used
for the repair of reinforced concrete structures in the UK and worldwide. Cathodic protection
generally works by the passing of a small electrical current from the anode to the corroding steel
reinforcement thereby protecting it from further deterioration by increasing the hydroxyl ions
locally. This paper has looked at the advantages and disadvantages of using the two types of
cathodic protection systems, namely sacrificial anode and impressed current CP, and highlighted
some of the design considerations and challenges faced on a number of case histories that
Mouchel have undertaken. From our experience the decision whether to use an impressed current
CP system or a sacrificial anode CP system is influenced by a number of factors including but
not limited to the condition (the level and extent of deterioration) of the struc ture, the client’s
budget and the anticipated life expectancy of the structure following the repairs. Experience at
Mouchel indicates that the circumstances where SACP is most suitable includes small and
targeted repairs, repairs where budget costs are limited and repairs where the life expectancy is
anticipated to be around 10 years. On the other hand, ICCP is generally used to address
significant corrosion problems to large structures and surface areas, where life expectancy is
expected to be more than 25 years and where access and traffic management are challenging and
very costly.
Pendahuluan
Cathodic protection (CP) is an electrochemical repair technique that has increasingly been used
for the repair of reinforced concrete structures in the UK and worldwide. Cathodic protection
generally works by the passing of a small electrical current from the anode to the corroding steel
reinforcement thereby protecting it from further deterioration by increasing the hydroxyl ions
locally. At Mouchel, cathodic protection has mainly been incorporated with concrete repairs as a
means of rehabilitating deteriorated highway concrete structures with varying levels of chloride
contamination, corrosion and spalling. However, we have also implemented the use of cathodic
protection on other reinforced concrete structures including car parks, tunnels, ports and harbor
facilities (jetties/wharves), industrial and residential buildings and marine structures. The two
principal types of cathodic protection systems commonly used are the impressed current cathodic
protection (ICCP) and the sacrificial anode cathodic protection (SACP). The decision on which
of the two cathodic protection (CP) systems to use is usually also influenced by a number of
factors including but not limited to the condition of the structure, the client’s budget and the
anticipated life expectancy of the structure following the repairs. This paper discusses the
advantages and disadvantages of

2. the two generic cathodic protection systems and highlights the factors that have determined their
selection and use on a variety of structures that have been encountered at Mouchel. It also
highlights the factors that influenced the selection of the appropriate repair option in each of the
case histories mentioned and outlines the specific challenges that were encountered during the
design and installation phases.
2. Impressed current cathodic protection (ICCP)
2.1. What is impressed current cathodic protection (ICCP)
The majority of cathodic protection systems applied to reinforced concrete structures
internationally, and particularly in the UK, are impressed current cathodic protection (ICCP)
systems. ICCP systems arrest steel reinforcement corrosion activity by supplying electrical
current from an external source to overcome the ongoing corrosion current in the structure.
ICCP involves the permanent installation of a low voltage, controlled electrical system
which passes direct current to the steel so that all of the steel is made into a cathode, thus
preventing the steel from corroding. The anode can be applied on the surface of or drilled into
small holes in the structure. It is the main electrochemical treatment that provides protection that
can be effectively monitored and controlled in the long term.
The main components of a typical ICCP system include the anode system, reinforcing
steel, electrolyte (in the concrete), cabling, monitoring devices, e.g. reference electrodes and a
direct current (dc) power supply. Protection is provided by connecting the impressed current
anode to the positive terminal and the reinforcing steel to the negative terminal of a dc power
supply. The direct current is normally provided by an ac powered transformer rectified or
equivalent power supply. Typical dc power supply outputs are in the region of 1–5 A and 2–24 V
to each independently controlled anode zone. The main benefit of ICCP is its flexibility and
durability. The current output of the power supply can be adjusted to optimise the protection
delivered. ICCP systems can be controlled to accommodate variations in exposure conditions
and future chloride contamination.
The durability of ICCP systems is largely determined by the choice of anode. This is
because the damaging reactions are moved from the steel to the installed anode. There are a
number of impressed current anode systems for reinforced concrete on the market. These include
conductive coatings, titanium based mesh in cementitious overlay, conductive overlay
incorporating carbon fibres, flame-sprayed zinc and various discrete anode systems. There are a
range of factors which influence the selection of impressed current anodes for ICCP systems for
particular applications. These include environmental conditions, anode zoning, accessibility,

3. maintenance requirements, performance requirements and operating characteristics, life
expectancy, weight restrictions, track record and costs.
2.2. Advantages of impressed current CP (ICCP)
The application of ICCP systems means that significant cost savings are possible due to minimal
concrete removal (limited physical repair) as ICCP requires that only physically unsound
concrete i.e. delaminated, honeycombed, cracked concrete be removed while chloride-
contaminated but sound concrete is left in place. As a result, ICCP retains more of the original
structure with less effect on aesthetics. Consequently, the installation of ICCP systems eliminates
the need for removing chloride-contaminated but sound concrete with associated reduction of
noise, dust, disruption and propping. Installation of ICCP also limits the need to cut behind the
reinforcement.
ICCP controls corrosion at any chloride level regardless of present or future chloride
levels or carbonation. It controls pitting and general corrosion and prevents accelerated corrosion
around repairs. ICCP can be applied to specific elements, e.g. crossheads or to entire structures
and can be used to protect any buried or sub merged metallic items. ICCP has a proven track
record in the UK. In 1986, full scale CP site trials were undertaken in the UK, on the Midland
Links Motorways Viaducts around Birmingham. The work was undertaken on behalf of the
Department of Transport (now the Highways Agency). The trials showed that CP stopped
corrosion and confirmed it as a cost effective solution to deal with the chloride affected
reinforced concrete structures. As a result, ICCP has been adopted as the major rehabilitation
method to stop corrosion on the Midland Links structures, with more than 100,000 m2 Of
concrete being protected using this technique. The high confidence gained in CP has lead to its
wide application elsewhere in the UK on reinforced concrete structures including bridges (bridge
decks and substructures), car parks, tunnels, ports and harbour facilities (jetties/wharves),
industrial and residential buildings and marine structures.
As a consequence of the experience gained fromthe above, good specifications and
standards have been developed over time and are now available to assist with the design,
installation and performance monitoring of ICCP systems, which can be designed with up to 30
years design life subject to the quality of the existing concrete. However, an impressed current
CP system could in theory have a life expectancy of between 10 and 120 years depending on the
type of anode system selected and the monitoring and maintenance regimes put in place. Any
electrical components and cabling would be expected to be renewed after about 20 years but with
proper design, monitoring and maintenance, the period to first maintenance can be well in excess
of this time frame.
Impressed current CP systems can be divided into zones to account for different levels of
reinforcement, different environments or different elements of the structure. It can also be

4. utilised to provide protection to critical reinforcement at great depths i.e. along the length of half-
joints and deep bearing shelves. With ICCP systems, various remote monitoring and control
options are available to enable selective and continuous monitoring to be undertaken for each
anode zone.
2.3. Disadvantages of impressed current CP (ICCP)
The application of ICCP mandates the structures owner to undertake regular monitoring in order
to assess the levels of cathodic protection being afforded to the structure. There is, therefore, an
ongoing cost of electrical power (usually insignificant) and cost
of specialist monitoring, control and assessment. Competent, highly trained & specialised
persons are required in order to monitor ICCP system performance for the service life of ICCP
systems.There is an initial high cost outlay to install ICCP systems and future regular
maintenance/controlling costs are approximately £2,500/annum to ensure effectiveness of
system.
ICCP requires a constant electrical power (permanent power) supply and where none is
locally available arrangements must be made and allowed for in the costing. In the case of the
impressed current CP systems utilising discrete anodes extensive drilling is required as part of
the installation process. The drilled holes and chases have an impact on the appearance of the
structure and there is also concern about Health and Safety issues due to the risk of vibration
white finger through the use of extensive drilling. In addition, there are installation problems
associated with the use of certain impressed current anode systems such as discrete anodes in
areas of congested steel and the application of discrete anodes to the soffits of structural
elements. Also, discrete anodes occasionally have problems associated with achieving sufficient
current distribution when compared with surface applied impressed current anode systems.
The interface between cementitious overlay and bearing shelves in the case of the
MMO/Ti impressed current anode system acts a potential point of weakness as ponding/excess
seepage can potentially cause freeze/thaw action. ICCP system power supplies, monitoring
systems and their enclosures are often vulnerable to environmental damage, in particular
vandalism and to atmospheric corrosion. Cabling and control boxes associated with ICCP
systems are required to be strategically placed in order to avoid the risk vandalism.
Certain impressed current anode systems such as conductive coating anode systems
cannot tolerate water during installation or prolonged wetting during operation. They also do not
tolerate traffic or abrasion. Bulky equipment is required for the installation of certain impressed
current anode systems, e.g. the Thermally Sprayed Zinc anode system.
The cementitious overlay for the MMO/Ti mesh and overlay anode systemchanges the
profile, loading, appearance and clearances of a structure. Clearance may be an issue, e.g. on the
soffit of over-

5. bridges, around bridge bearings or in car parks. When an ‘as shot’ appearance is unacceptable
then a flash coat would need to be applied in order to achieve the desired finish.
Due to the risk of hydrogen evolution and possible occurrenceMof hydrogen
embrittlement on high strength steels ICCP is not routinely applied to any prestressing or post
tensioned elements
without specific consideration for suitable safeguard criteria. Provided the tendons are in
good condition with no corrosion then the use of ICCP is usually considered with suitable
safeguard criteria involving the minimisation of overprotection and the use of appropriately
placed monitoring probes at carefully selected locations, together with appropriately screened
cables.
The use of impressed current CP systems in the presence of Network Rail lines and
equipment or other electrical systems needs to be strictly controlled in order to prevent incidents
of stray current interfering with associated overhead line/equipment and track signalling
equipment. In addition, any isolated reinforcement steel or adjacent surface mounted steelwork
must be made continuous with the ICCP system in order to prevent stray current corrosion.
2.4. Sample case histories
2.4 Mouchel were commissioned to carry out a special inspection of a 68 span, pre-stressed, pre-
tensioned concrete beam and slab bridge carrying a single lane carriageway in a tidal estuary that
was experiencing concrete deterioration due to reinforcement corrosion. The bridge comprises of
two abutments and 67 piers, with each pier comprising of transverse reinforced concrete
crossheads or capping beams with inverted ‘T’ construction. From the special inspection, it was
concluded that the major cause of concrete deterioration was chloride induced corrosion of the
steel within the piers, in particular the inter-tidal zone. This was a consequence of deicing salts
being sprayed onto the road in poor weather conditions, along with the salt spray from the sea
itself. The corrosion of the reinforcement had caused cracking and disruption and spalling of
concrete cover.
2.4.1. Case 1 – bridge piers
It was deemed that the most practical way to address the corrosion problems without
significantly altering the geometry, aesthetics and structural integrity of the bridge was to
incorporate an electrochemical repair solution alongside concrete repairs. Various
electrochemical repair options were considered including concrete replacement, chloride
extraction and cathodic protection and the
impressed current CP was chosen as the most cost effective repair option that is likely to
meet the client’s requirements which includes a minimum life expectancy of 30 years. The ICCP

6. was designed and installed for four of the piers as part of the major trial repairs carried out to the
bridge, with other piers to follow pending the outcome of the trial installations.
The design of the ICCP system was based on two anode types Mixed metal oxide coated
expanded titanium mesh in a cementitious overlay (approx. 730 m2 of anode coverage) and
Discrete anodes installed at two depths (Ebonex CP10/300 installed horizontally at 450 mm
depth, and Ebonex CP10/1300 installed vertically at 1450 depth). The two anodes were utilised
in 5 zones distributed on each bridge pier as shown below:
 Zone 1 – Stem wall and top surface of capping beam.
 Zone 2 – Diaphragm walls.
 Zone 3 – Capping beam soffit, sides and ends.
 Zone 4 – Atmospherically exposed part of columns to mid-tide level.
 Zone 5 – Submerged part of columns from mid-tide to bed level.
The zoning arrangement is shown in Fig. 1 while the orientation of the discrete anodes
protecting zone 1 is shows on Fig. 2 below. The pier was divided into five zones to give targeted
and controlled protection to the various elements of the pier and the client’s requirement was to
include remote monitoring and control in order enable monitoring offsite and thus less need for
site visits and traffic management. The number of reference electrodes per zone ranged from 4 to
8 and these numbers were chosen to enable close monitoring and control in the presence of the
prestressing steel.
Some of the risks, hazards and challenges that had to be dealt with in the design and
installation of the CP system were the presence of Macalloy bars, prestressing beams, working
over water, hazardous materials, working at height and the presence of services.
2.4.2. Case 2 – highway bridge structures
Mouchel has been responsible for ICCP related projects on a 21 km section of elevated
motorway, comprising of some 1200 crossbeams and 3600 columns on a major UK roads
network. The structures involved in the network have included the largest concentration of CP
installations in Europe. ICCP was adopted by the Client (UK Highways Agency) as a viable
repair option for the substructures on the network and remains at the forefront of all structural
renewal schemes on the network. Mouchel was responsible for CP from the feasibility stage
through to the design, specification and contract supervision of the installation of CP schemes on
all structural renewal schemes on the network, some of which were up to £12 million in contract
value.
Mouchel was involved with the management, monitoring and performance verification of
existing CP systems installed to more than 700 structures to ensure that the CP systems were
performing satisfactorily. Mouchel were also involved in the development of a

7. strategy to repair and maintain old/existing CP systems that were nearing the end of their design
lives. The strategy included the consideration of the following factors:
 Cyclical maintenance/renewal.
 Anode life expectancy.
 Whole life cost issues.
 Choice of replacement anodes.
 Integrating works with other cyclical measures.
 Minimising disruption to the travelling parties.
The choice of ICCP as the most suitable repair option was made from a number of repair options.
The repair options considered were crossbeam replacement, concrete replacement (chloride
threshold), and surface treatment (coatings). ICCP was chosen for the principal advantage that
the repair option offers a life
GAMBAR 1 DAN GAMBAR 2
expectancy greater than 15 years and it reduces structural impact in addition to minimising
disruption to travelling parties. The properties and advantages of ICCP outlined in Sections 2.1
and 2.2, respectively, were instrumental in enabling various anode
systems to be designed and installed on these highway structures. Environmental factors, whole
life costs and methodology for the choice of anodes were some of the other factors that were
considered. The impressed current anode systems used for CP systems on these highway
structures included the following:
 Conductive paint anode system.
 MMO/Ti mesh and overlay anode system.
 MMO/Ti mesh ribbon anode system.
 Conductive overlay anode system.
 Various discrete probe anodes.
On a typical pier at this highway viaduct, the design of the ICCP system would be based on
any of the above anodes or a combina tion depending on the configuration of the structural
elements, the exposure conditions, headroom restrictions and other relevant local factors. Each
pier was divided into four zones to give targeted and controlled protection to the various
elements of the pier. Some of the older ICCP systems only included manual monitoring which
meant regular site visits and the use of Mobile Elevating Working Platforms (MEWPS) and
occasionally traffic management. However, since about year 2000, all new CP systems installed
have included remote monitoring and control as standard. The number of reference electrodes
per zone ranged from 2 to 6 and these numbers were chosen to enable appropriate monitoring
and control of the installed systems.

8. Some of the risks, hazards and challenges that had to be dealt with in the design and
installation of the CP system were the presence Macalloy bars, working close to a river,
hazardous materials, working at height and the presence of services. For a mesh and overlay
system, a load carrying capacity check for the effects of any additional loading due to the applied
cementitious overlay was undertaken as part of the detailed design of the concrete repairs.
With a large number of piers to be repaired over time, the approach and criteria that was
used to complete the electrical design aspects of the ICCP systems was required to be consistent
and standardised. Also, the client was seeking consistency in the design and material types
specified in order to encourage standardization from contract to contract.
3. Sacrificial anode cathodic protection (SACP)
3.1. What is sacrificial anode cathodic protection (SACP)
A sacrificial anode is a form of cathodic protection, it is made from a metal alloy from the
galvanic series which has a more negative electrochemical potential than the steel reinforcement
of the structure [1]. This works because the difference in potential between the anode and steel
causes a positive current to flow in the electrolyte, making the steel more negatively charged,
thus becoming the cathode. The difference in potential between the steel reinforcement and the
sacrificial anode, indicated by their relative positions in the galvanic series, means that the
galvanic anode corrodes (sacrificed) in preference to the steel. The sacrificial anodes are directly
electrically connected to the steel to be protected. Metals that are commonly used as sacrificial
anodes are aluminum, zinc and magnesium. These metals are also alloyed to improve the long-
termperformance and dissolution characteristics[2].
3.2. Advantages of SACP
Unlike ICCP, an external power source is not required to install SACP. This greatly
reduces the start up costs as no provision has to be made to connect to a power supply. Also, the
SACP system is easier to maintain and this leads to significantly less minimal running costs
throughout the life of the system. In addition, the SACP system voltages and current outputs are
lower compared to the ICCP system, leading to a low risk of cathodic interference in adjacent
structures. Consequently, the imposed potential is unlikely to exceed the
900 mv defined in BS EN 12696:2000 as being capable of
inducing hydrogen embrittlement of steel reinforcement [3].
Sacrificial anodes are relatively easy to install, as sound but chloride contaminated or
carbonated concrete does not require replacement, only specific areas require concrete breakout.
Repairs can be targeted; focusing on specific areas of deterioration or elements of the structure,
preventing inefficient protection of the steel and therefore keeping costs down. The anode also

9. controls corrosion in areas adjacent to concrete repairs that would normally require removal if
only conventional concrete patch repair was carried out. Since concrete breakout is minimised, it
is unlikely that temporary works such as structural propping, which is expensive, will be required
during repair [4]. Also with minimal breakouts, uncertainties over structural behaviour due to
redistribution of stresses are reduced. These all leads to less traffic disruption as the remedial
works can be completed in a shorter timeframe.
A SACP system is easier to design and specify as it has fewer critical components, with
the main critical component being the anode itself. The system is considered to be a sustainable
option as it is making the most of the structure in its current form and extending its life through
relatively minor repair work. There is also less waste going to landfill as often relatively little
concrete is broken out and repaired.
There is also an issue of on going liabilities; many Highways Agency (HA) structures
aremaintained as part of a Managing Agent Contract (MAC) which is run by a contractor for a
period of time, this means that a structure could be maintained by several different managing
agents throughout the SACP system’s life. The handover of an SACP system is much less
involved, requiring no document handover, data exchange or knowledge transfer.
Overall the SACP system is much cheaper than the ICCP system, in the short and
medium term, is easier to install, no monitoring is required and it causes less disruption as less
time is required on site.
3.3. Disadvantages of SACP
The main disadvantage is the uncertain lifespan of the anodes the life expectancy of the
system is dependant upon the average current output of the anodes. The anodes only have a finite
amount of material available for sacrifice and a higher current uses up that material at a higher
rate. Changing conditions can affect the current output of the anode. Factors which are known to
affect the current output are chloride content, temperature, oxygen content and humidity.
There is no way of knowing when all of the material in the anodes have been used up and
the anode has stopped working, this is a predicament, as new deterioration is likely to be the first
sign that the anodes are spent [5].
Compared to ICCP, the current output of the SACP system is limited and this means that
the current output cannot be altered over time to compensate for changing conditions [2]. There
is no way of adjusting the SACP system other than adding or taking away anodes and because
the system is not monitored in the same way as ICCP, it is difficult to know when adjustments
are required; this may lead to a failure to arrest active corrosion.

10. Monitoring of an SACP system takes the form of survey at set intervals to monitor for
signs of deterioration. Although there are no running costs associated with the system itself, the
structure requires a regular visual and delamination survey to monitor its condition; however,
this can be done during the structures regular inspection schedule [4].
As a design consideration, the resistivity of the concretemust be taken into account as the
lower driving voltage of the anodes means they may not work in high resistivity environments. If
there is significant loss of section to the steel reinforcement, steel replacement needs to be carried
out at the same time anodes are installed as no cathodic protection system can restore lost metal.
3.4. Sample case histories at Mouchel
3.4.1. Case 1 – bridge abutments
During a routine principal inspection, concrete at the base of the abutments at an
Interchange comprising two portal frame bridges was found to be deteriorating. The principal
inspection found that deterioration was causing delamination and spalling of the concrete and
some areas of section loss to the steel reinforcement, see Fig. 3.
A special inspection was commissioned to find the cause of the deterioration. It found
high levels of chloride ion ingress in the concrete which initiated corrosion in the steel
reinforcement. The chloride ion ingress is believed to be caused by de-icing salts on the road
spraying up onto the abutments ‘splash zone’ over a number of years. This helped us focus on
repair options specifically for chloride induced corrosion. After conducting feasibility study the
chosen option was to carry out conventional patch repairs with sacrificial anodes, Galvashield
XPs, placed into the patch repairs and Galvashield CCs in the adjacent sound concrete, along
with an elastomeric coating. It was recommended that the sacrificial anodes and coating be
applied along a 1 m band above and 0.2 m immediately below ground level for the entire length
of the abut ments of both bridges as this prevents further deterioration in the critical ‘splash
zone’.
The accepted best practice on Highways Agency structures was to remove and replace all
concrete where chloride ion contents exceeds 0.3% by weight of cement at the depth of
reinforcement. This would have lead to a large volume of concrete being removed and replaced.
However, not all of the chloride contaminated concrete was deteriorated, so whilst concrete
repair was carried out to the deteriorated areas, corrosion was controlled using the SACP system,
therefore leading to less concrete being broken out and a shorter time on site. Fig. 4 shows
typical anode layout for the SACP design.
Mouchel decided to use an SACP system for several reasons and constraints. The main
constraints were the amount of traffic management that was needed to complete the site works,
we could close one lane of the roundabout at a time, keeping one lane open thus allowing us to
work on one abutment per bridge and then switching the lane closures to the other lane so that

11. we could complete works on the remaining abutment of each bridge. The other major concern
was the timing of the site works, because the interchange is a main access route for holidays to
Devon and Cornwall, we needed a system that could be installed quickly and easily to ensure
that work was complete before the holiday season. As no temporary works or special access was
required the site works could be completed quickly.
3.4.2. Case 2 – car park structure
In a similar way to bridges, car parks suffer from corrosion caused by chloride ion
ingress. As part of a car parks ‘life care plan’ it undergoes a schedule of inspections and
maintenance to ensure the long term integrity of the car park and keep it safe for public use.
During several routine inspections over a period of years it was noted that areas at the base of the
columns and localised areas on the deck were exhibiting deterioration. An investigation was
carried out to determine the cause of the observed deterioration. The findings from the
investigation showed that the car park was in a poor to fair condition with areas of reinforcement
corrosion occurring in the deck and base of the columns due to the presence of chlorides; which
is deemed to be a direct result of leaking down pipes, de-icing salts being brought into the car
park on vehicle wheels, and the direct use of de-icing salts on the car park. Fig. 5 shows a typical
example of spalling to the car park deck structure.
Due to the size and nature of the deterioration conventional patch repairs with sacrificial
anodes (Galvashield XPs) placed with in the repairs was recommended at deteriorated locations
on the deck concrete. For the base of the columns the same solution was recommended, but in
addition, sacrificial anodes (Galvashield CCs) were installed in sound concrete to unaffected
columns as a way of preventing future deterioration. Mouchel advocated sacrificial anodes in the
patch repairs to prevent incipient anode formation immediately adjacent to the patch repairs.
Sacrificial anodes were used as part of this repair strategy because traditional
conventional patch repairs would not last very long in such an aggressive environment due to
incipient anode formation. Also the operation to place the anodes in the patch repair is simple
thereby reducing repair time and cost. It is not considered cost effective to replace chloride
contaminated elements such as the deck structure because of the revenue the car park will lose
out on whilst the repairs are being carried out; the work itself is also very costly. Also, ICCP was
not considered viable as the deck was made up of many one way spanning slabs and electrical
continuity would be very difficult to achieve throughout the whole deck, making the installation
process very expensive and time consuming.

12. GAMBAR 3, 4 DAN 5
4. Conclusions
This paper has looked at the advantages and disadvantages of using the two types of
cathodic protection systems and highlighted some of the design considerations and challenges
faced on a number of case histories that Mouchel have undertaken.
Mouchel has been involved in the design, supervision and monitoring of cathodic
protection systems and can conclude that cathodic protection is now a widely used and accepted
repair method for arresting corrosion of reinforcement in concrete structures. It is normally used
alongside concrete repairs to minimize the extent of conrete breakout, thereby maintaining
concrete intergrity and aesthetics.
Mouchel has used the technique of cathodic protection to apply repair solutions to a large
number of structures over time. From our experience the decision whether to use an impressed
current CP system or a sacrificial anode CP system is influenced by a number of factors
including but not limited to the condition (the level and extent of deterioration) of the structure,
the client’s budget and the anticipated life expectancy of the structure following the repairs.
Both the sacrificial anode CP system and the impressed current CP system are
appropriate repair options that can be used in the right circumstances. Our experience at Mouchel
indicates that the circumstances where SACP is most suitable includes small and targeted repairs,
repairs where budget costs are limited and repairs where the life expectancy is anticipated to be
around 10 years. On the other hand, ICCP is generally used to address significant corrosion
problems to large structures and surface areas, where life expectancy is expected to be more than
25 years and where access and traffic management are challenging and very costly.