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CORRECTIONS WITHIN DESIGN MANUAL FOR ROADS AND BRIDGESNOVEMBER 2002

SUMMARY OF CORRECTION - BA 83/01 Volume 3, Section 3, Part 3CATHODIC PROTECTION FOR USE IN REINFORCED CONCRETE HIGHWAY STRUCTURES

BA 83/02 was originally produced in partnership with the Corrosion Prevention Association (CPA).Following its publication and as a result of some feedback, it was agreed with the CPA that the diagramsshowing cathodic protection systems could be clarified. It was also agreed that Table 1 could be amended toreflect the latest information on the performance and application of different anode types.

Please remove pages 2/1 - 2/8 dated Febuary 2002 and insert new pages 2/1 - 2/8 attached, dated November2002.

We apologise for the inconvenience caused.

Highways AgencyNovember 2002

London: The Stationery Office

February 2002

DESIGN MANUAL FOR ROADS AND BRIDGES

VOLUME 3 HIGHWAY STRUCTURES:INSPECTION ANDMAINTENANCE

SECTION 3 REPAIR

PART 3

BA 83/02

CATHODIC PROTECTION FOR USE INREINFORCED CONCRETE HIGHWAYSTRUCTURES

SUMMARY

This Advice Note gives guidance on the selection andinstallation of cathodic protection systems for thecorrosion protection of reinforcement in highwaystructures. It has been produced in partnership with theCorrosion Prevention Association.

INSTRUCTIONS FOR USE

This is a new Advice Note to be incorporated in theManual.

1. Remove existing contents page for Volume 3, andinsert new contents page for Volume 3, datedFebruary 2002.

2. Insert BA 83/02 into Volume 3, Section 3, Part 3.

3. Archive this sheet as appropriate.

Note: A quarterly index with a full set of VolumeContents Pages is available separately from TheStationery Office Ltd.

BA 83/02

Cathodic Protection for Use inReinforced Concrete Highway

Structures

Summary: This Advice Note gives guidance on the selection and installation of cathodicprotection systems for the corrosion protection of reinforcement in highwaystructures. It has been produced in partnership with the Corrosion PreventionAssociation.


THE HIGHWAYS AGENCY

SCOTTISH EXECUTIVE DEVELOPMENT DEPARTMENT

THE NATIONAL ASSEMBLY FOR WALESCYNULLIAD CENEDLAETHOL CYMRU

THE DEPARTMENT FOR REGIONAL DEVELOPMENTNORTHERN IRELAND

Volume 3 Section 3Part 3 BA 83/02

February 2002

REGISTRATION OF AMENDMENTS

Amend Page No Signature & Date of Amend Page No Signature & Date ofNo incorporation of No incorporation of

amendments amendments

Registration of Amendments

VOLUME 3 HIGHWAY STRUCTURES:INSPECTION ANDMAINTENANCE

SECTION 3 REPAIR

PART 3

BA 83/02

CATHODIC PROTECTION FOR USE INREINFORCED CONCRETE HIGHWAYSTRUCTURES

Contents

Chapter

1. Introduction

2. Description of Cathodic Protection Systems

3. Assessment Prior to Cathodic Protection

4. Cathodic Protection System Options

5. Design Process and Procurement

6. Installation

7. Performance Assessment, Inspection andMaintenance

8. Bibliography

9. Enquiries


February 2002


Chapter 1Introduction

1. INTRODUCTION

Scope

1.1 This Advice Note provides general informationon the merits, selection and installation of various typesof cathodic protection for the control of corrosion ofreinforcement in reinforced concrete highwaystructures.

It relates principally to reinforced concrete highwaystructures at risk of reinforcement corrosion damagedue to chloride contamination.

Cathodic protection is an electrochemical processinvolving the use of low voltage dc electricity which iscaused to flow through the concrete and discharge onthe reinforcement resulting in control of corrosion toinsignificantly low rates.

This Advice Note also addresses the use of cathodicprotection for new structures in chloride contaminatedenvironments (also known as “cathodic prevention”).

It also gives guidance on particular cases wherecathodic protection may not be appropriate.

This Advice Note should be used in conjunction withother DMRB Advice Notes and Standards in order toensure that cathodic protection is only applied to thosestructures that have been properly and fully assessed inorder to determine the causes of their deterioration, thatcathodic protection along with associated repair and/orstrengthening works is the most appropriate techniqueto extend the life of the structure and that repaired/protected structures will be fit for purpose following theworks.

European Standard

1.2 This Advice Note is in accordance with theBS EN 12696:2000, “Cathodic Protection of Steel inConcrete.”

The BS EN 12696 Standard is a performance standardfor cathodic protection of steel in concrete which isapplicable to highway structures. It provides moredetail of the technique, and specifications for cathodicprotection of reinforced concrete highway structuresshould comply with BS EN 12696.

February 2002

Corrosion Prevention Association

1.3 This Advice Note has been prepared with theassistance of the Technical Committee of the CorrosionPrevention Association (formerly the Society forCathodic Protection of Reinforced Concrete). Membersof the Association are a source of expertise in cathodicprotection of reinforced concrete and includeConsulting Engineers, Contractors and MaterialSuppliers.

History

1.4 Cathodic protection of steel in soils and watershas been practised for over 150 years. Cathodicprotection of steel in concrete has been practised forsome 50 years, starting with applications to steelreinforced concrete pipelines. Trial applications toatmospherically exposed reinforced concrete highwaystructure elements commenced in 1958. Extensive trialsand full-scale demonstration projects followed bycommercial applications in North America in the 1980s.UK highways bridge demonstration projects in 1986and 1989 were followed by large scale commercialapplications, notably to the Midland Links MotorwaysViaducts support structures, starting in 1990.

Cathodic protection of atmospherically exposedreinforced concrete has, by the end of 2000, beenapplied to well in excess of 100,000m2 of bridges, carparks, harbour facilities, tunnels and buildings withinthe UK and well in excess of 2,000,000m2 overseas.Extensive research and trials have supported thisextensive and rapidly growing track record to establishcathodic protection as a technique of proven efficacyand reliability.

There has been extensive use of cathodic prevention ofnew highway structures in Italy with some significantlengths of post tensioned reinforced concrete deck unitsfor Autostrada receiving corrosion protection bycathodic protection.

1.5 Concurrently UK Consultants and Contractorshave been responsible for large scale projects ofcathodic protection applications to highway structuresand harbour facilities internationally, notably in theMiddle East and the Far East.

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Chapter 1Introduction

Cost Savings and Efficacy

1.6 Cathodic protection of reinforced concretehighway structures has been rigorously assessed, bothin the UK and internationally, and demonstrated to bereliable and effective in controlling corrosion ofreinforcing steel in chloride-contaminated concrete.Experience on such structures has demonstrated that theuse of cathodic protection, as an alternative to extensiveremoval and repair of chloride-contaminated concrete,can significantly reduce contract costs, particularlywhen contract durations are reduced and the need forstructural propping is avoided. The reduction of largescale concrete removal and reinstatement can result incontract cost reductions of between 20% and 80%.

System Selection and Life

1.7 In the highway structure environment, differenttypes of cathodic protection system are available, withdifferent operating characteristics. Satisfactoryperformance before maintenance can be expected torange from 10 to 40 years, depending upon system type,with embedded components of some systems having atheoretical design life of up to 120 years. However,electronic power supply and monitoring systems arelikely to require replacement every 20 to 40 years.

System Monitoring and Long Term Costs

1.8 Cathodic protection requires that the impresseddirect current (d.c.) flows either continuously or for themajority of the time. It is necessary to monitor thiscurrent flow and to intermittently monitor the effects ofthe cathodic protection on the steel/concreteelectrochemical performance in order to demonstratethat corrosion control has been achieved. There istherefore an ongoing cost associated with electricalpower (normally insignificant) and a cost of specialistmonitoring, control and assessment to be incorporatedinto life cycle cost analysis.

February 20021/2

Chapter 2Description of Cathodic Protection Systems

ODIC PROTECTION



2. DESCRIPTION OF CATHSYSTEMS

General

2.1 There are two types of cathodic protectionsystems, impressed current and galvanic (also known assacrificial). Both are discussed in this Advice Note,although galvanic anode systems have had limited useand are still considered experimental in UKapplications to atmospherically exposed reinforcedconcrete structures.

2.2 The principles of cathodic protection arestraightforward. Corrosion occurs by the formation ofanodes and cathodes on the reinforcement surface, asshown in Figure 1. Corrosion occurs at the anode; agenerally harmless reduction reaction occurs at thecathode. By introducing an external anode and anelectric current, the reinforcement is forced to becomecathodic and reduces corrosion to insignificant levels.The impressed current cathodic protection anode is amaterial that is consumed at a negligible or controlledrate by the anodic oxidation reaction.

Impressed Current Cathodic Protection

2.3 Impressed current cathodic protection consists ofan anode system, a d.c. power supply and monitoringprobes, with associated wiring and control circuitry.One of the key decisions is the choice of anode. Thealternatives are conductive coatings applied to theconcrete surface, mixed metal oxide coated titaniummesh or grid in a concrete overlay, conductive mortarand overlays, coated titanium ribbon in slots, or variousdiscrete anode materials in holes in the concrete. Aschematic of an impressed current system is shown inFigure 2.

2.4 Figure 2 depicts an atmospherically exposedconcrete structure where anodes are distributed acrossthe concrete surface to pass current evenly to thereinforcing steel. For buried or submerged concreteremote anodes can pass current through low-resistancesoil or water. In this application conventional cathodicprotection as used for pipelines or submerged structurescan be employed, as shown in Figure 3 (see alsoBS 7361: Part 1:1991).

Anode Systems

2.5 Available conductive coating anodes include avariety of formulations of carbon pigmented solvent or

November 2002 - Correction

water dispersed coatings, and thermal sprayed zinc.Recently, thermal sprayed titanium has been usedexperimentally, with a catalysing agent spray appliedonto the titanium coating.

2.6 Mixed metal oxide coated titanium mesh or gridanode systems are fixed to the surface of the concreteand overlaid with a cementitious overlay which can bepoured or pumped into shutters or sprayed.

2.7 Discrete anodes are usually installed in purpose-cut holes or slots in the concrete. They are either:

• rods of coated titanium in a carbonaceousbackfill;

• mixed metal oxide coated tubes;

• strips and ribbon;

• conductive ceramic tubes in cementitious grout.

Table 1 summarises the anode types and their relativeperformance. It is emphasised that the information inTable 1 is indicative only and based upon theexperience in the UK to year 2000. Preliminaries,access, traffic management and concrete repair costs arenot included.

For any particular application, the CP specialist mustensure that the chosen anode system and its design aresuitable for the application.

Power Supplies

2.8 Cathodic protection generally operates with acurrent density to the steel surface in the range5-20mA/m2. The direct current is normally provided byan a.c. powered transformer-rectifier or equivalentpower unit, taking single phase a.c., transforming it tolower voltage and rectifying it to d.c. and outputting itat typically 1-5 ampere, 2-24 volts to eachindependently operated anode zone. Thus it can be seenthat the electrical consumption of an impressed currentcathodic protection system is very modest. An anodezone is an electrically isolated area of anode. Each zonecan receive different levels of current. Systems aredivided into zones to account for different levels ofreinforcement, different environments or differentelements of the structure.

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Cathodic prevention of new or not yet corrodingreinforcement in concrete requires a current density tothe steel in the range 0.5-2mA/m2. The lower currentdensity results in good current distribution and safeapplication to prestressed structures.

A permanent power supply will be required forimpressed current cathodic protection systems, andwhere none is locally available arrangements must bemade, and allowed for in the assessed system costs. Insome situations street lighting supplies can be usefulsources of power.

2.9 Transformer-rectifiers may be manuallycontrolled or controlled either locally or remotely viamodem to a computer.

Monitoring System

2.10 The monitoring system is usually closelyintegrated with the power supply. As shown in Figure 2probes are embedded in the concrete to verify that all ofthe zones are working and that sufficient current ispassing to protect the reinforcement. Monitoring ofsteel/concrete potential is with respect to embeddedreference electrodes. These are usually silver/silverchloride/potassium chloride or manganese/manganesedioxide/potassium hydroxide. They are placed in theconcrete in the most anodic (actively corroding) areasprior to energising the system.

Additional reference electrodes are placed in theconcrete at locations of particular structural sensitivity,at locations of high reinforcement complexity or atlocations of sensitivity to excessive protection.

Steel/concrete/reference electrode (so called “half cell”)potentials are recorded and the decay in potential from“instant off” (a measure of the potential without IRerrors, see Chapter 4) to a time of 4 to 24 hours orlonger is used to determine the effectiveness of thesystem. A 100mV change in 24 hours or 150mV over alonger period is specified in BS EN 12696, along withcertain other criteria.

Earlier UK and USA practice to require a 100mVpotential decay in 4 hours will result in adequateprotection but, particularly after long periods ofoperation, is likely to result in excessive protection.

2.11 It is usual to embed several reference electrodesin each zone of the cathodic protection system. Thecathodic protection current can be interrupted and steel/concrete/reference electrode potentials and potentialdecays measured.

2cmv

G

2tempccrmdi

2caas

2/2

.12 Computerised monitoring systems allow theollection of decay data to be automated. Remoteonitoring systems allow this to be done without a site

isit.

alvanic Anode Cathodic Protection

.13 The principles of galvanic cathodic protection arehe same as for impressed current cathodic protection,xcept that the anode is a less noble (ie more active)etal than the steel to be protected and is consumed

referentially, generating the cathodic protectionurrent. The potential difference between anode andathode is a function of the environment and theelative electrode potentials of the anode and cathodeaterials. The current is a function of the potential

ifference and the electrical resistance. Figure 4llustrates a galvanic system.

.14 As the voltage and current cannot generally beontrolled, the level of protection cannot be guaranteednd a low resistance environment is required. Galvanicnodes are well proven for applications to buried orubmerged structures.

February 2002

on cell

l not lead to disruptive forces but can

Chapter 2

Description of C

athodic Protection System

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Figure 1. Schematic of embedded reinforcement corrosi

Note 1 – In cases of low oxygen activity at the anode, “black rust” may form, which willead to rapid section loss and subsequent risk of structural failure.

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rotection

Chapter 2

Description of C


s

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art 3 BA

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Figure 2. Schematic diagram of impressed current cathodic p

Novem

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merged steel in concrete

Chapter 2

Description of C


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Figure 3. Impressed current cathodic protection schematic for buried or sub

2/5 - C

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tion system

Chapter 2

Description of C


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Figure 4. Schematic diagram of galvanic anode cathodic protec

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Table 1 – Anode Types and Characteristics

Typical InstalledAnode

Other Cost Incl.Performance Surface

ional & Queries (Seek Preparationmpact/ Specialist (2000 Costs)

lation Advice) See Notes 3-8

Some unproveno products £20-£40/m2

ted

Limited UKo experience £60-£100/m2

Health & Safetyduring application

l Spray

sOverlay Quality £60-£100/m2

Control including overlay 25mmlay

o

£40-£100/m2

in pre- holes

o

£40-£100/m2

to holeslots

sLimited £30-£60/m2

experience, circa

thick

Chapter 2

Description of C


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Long Term Supplier’sAnode Type Anode Current Long Term Typical Anode Suitable for DimensSee Note 1 Density per m2 Current Density Life Estimate Suitable for Wet Running Weight I

of anode per m2 concrete See Note 2 Structures Surfaces Instal

Conductive 20mA/m2 20 mA/m2

Organic Max Up to 15 years No No NCoatings

Pain

Sprayed zinc 20mA/m2 20mA/m2

max Up to 25 years Possibly No N

Therma

Mixed metaloxide coated 110-220mA/m2 15-110 mA/m2 Yetitanium (MMO Ti) varying grades Up to 120 years Yes Yesmesh and grid incementitious In circaoverlay over

Discrete MMO Ti 800mA/m2 from Circa 10-110 Nanodes, with carbonaceous mA/m2 subject tocarbonaceous surround Distribution Up to 50 years Yes, not tidal Yessurround

Placed drilled

Discrete anodes Nin cementitious 800mA/m2 Circa 10-110surround. mA/m2 subject to Up to 50 years Yes YesMMO Ti or distributionConductive Placed inceramic or s

Cementitious 20mA/m2 20mA/m2 Yeoverlay Max Up to 25 years Yes, not tidal Yes, underincorporating wearing coursenickel plated Sprayedcarbon fibre 8mm strands2/7

er 2002 - Correction



Table 1 Notes

Note 1. Anode technology for reinforced concrete is rapidly evolving. The information reflects only those systemsthat have been relatively widely used before Year 2002.

Note 2. The performance of each element of the complete anode system is as important as the durability of theanode itself. The latest literature and experienced specialists should be consulted when determining the life of anyparticular anode system for any particular application.

Note 3. Transformer-rectifier/manual monitoring and cabling costs are additional. Year 2000 costs can be budgetedas £1,000 to £2,000 + £10 to £20/m2.

Note 4. Remote monitoring and control capital costs are additional, Year 2000 costs are up to £6000.

Note 5. Future operation monitoring and control costs are extra.

Note 6. Preliminaries, access, traffic management and concrete repair costs are not included.

Note 7. For a typical 4 zone cathodic protection system, manual performance assessment and simple reportingregime costs (in 2000) are £1,500 - £2,500 per annum which can be reduced to £1,000 - £1,500 per annum by usingremote monitoring and one visual inspection.

Note 8. All life and cost information is indicative. This information is for pre-budget assessments only. Full
performance and cost details for individual systems and applications should be sought from specialists prior toselecting a particular system for a particular project.
2/8 November 2002 - Correction


Chapter 3Assessment Prior to Cathodic Protection

CATHODIC
3. ASSESSMENT PRIOR TOPROTECTION
General

3.1 Cathodic protection is generally selected for oneof two reasons, either it is the only technically suitabletreatment or it is the most cost effective treatment. Botharguments are structure specific and will require carefulassessment of the structure and its condition.

Evaluation of Structure

3.2 In order to determine the most technicallysuitable and cost effective repair, the structural,physical and electrochemical condition must bedetermined by examining the documentary evidence inthe form of inspection and testing reports and byspecific site investigation. It is essential to determinethe reasons for reinforced concrete deterioration.Cathodic protection may be considered as an optionwhen dealing with reinforcement corrosion, but notother forms of deterioration.

It is also important to understand the reinforcementdetails in order to choose the most suitable anode and todesign the system correctly. It is assumed that thestructural integrity is fully assessed and the structurewill be maintained in a safe condition before, duringand after treatment.

All available drawings and relevant records arereviewed to assess the location, quantities, nature(eg smooth, ribbed, galvanised, epoxy coated,prestressed) and electrical continuity of reinforcement.The available information is confirmed andsupplemented as necessary by site and laboratory testsas described below.

Life cycle cost analysis

3.3 Cathodic protection usually leads to significantwhole life cost savings compared with the alternatelong term repair option of removal and replacement ofall chloride contaminated concrete, when the entirerepair and maintenance cycle for the structure iscalculated.

Cathodic protection is likely to be an effective methodof corrosion control for those structures that require along residual life after repair. Further cycles of patching

February 2002

will be avoided and only maintenance of the anodesystem, cabling and electronics will be required.

Comparison of cathodic protection with othertechniques

3.4 When selecting a treatment for corrosiondamaged reinforced concrete, the advantages andlimitations of the different treatment methods must beevaluated. Irrespective of the selected treatment tocontrol or repair corrosion related damage it willnormally be advantageous to minimise future chloridecontamination by dealing with the source of theproblem, and the counteraction of leakages.Improvements to the provision or maintenance ofdrainage, replacement expansion joints andwaterproofing must be considered and the use of porelining impregnants such as silane (DMRB Vol.2.4.2BD 43 and MCHW Vol.1 and 2). The main treatmentsavailable for highway structures can be summarised asfollows:

i) Do Nothing - acceptable if either a short life isrequired or to await full or partial replacement.May be supplemented by other measures such asenclosure or some form of containment if there isa risk of concrete delamination. May besupplemented with corrosion monitoring (seebelow).

ii) Patch Repairs - Usually required prior to anyother treatment. Patches may exacerbatecorrosion in adjacent areas due to the “incipientanode” effect, where a corroding anodic area isprotecting the adjacent reinforcement, but oncepatch repaired the adjacent reinforcement startscorroding in chloride contaminated concrete.Discrete galvanic anodes may sometimes beincorporated into patch repairs in order to helpcontrol this phenomenon.

iii) Coatings – pore lining impregnants such as silaneare usually applied to elements exposed tochlorides before opening the structure to traffic.However, once sufficient chlorides are present atreinforcement depth then application will notstop corrosion but may reduce the corrosion rate.

3/1



iv) Concrete Replacement - it may be feasible toremove all corrosion damaged and chloridecontaminated concrete, eg where salt water rundown occurs in a well-defined area of a bridgesubstructure.

v) Cathodic Protection - will control corrosionacross the whole area treated. Reduction in extentof concrete repair, with associated reductions inprogramme period, noise, dust, propping andtraffic management. Cathodic protection usuallyrequires a permanent electricity supply to run thesystem and regular monitoring and adjustment byqualified personnel. If remote monitoring isinstalled then a permanent communication link isusually required.

vi) Electrochemical Chloride Extraction (also knownas desalination or chloride removal). Thisinvolves temporary power supplies, anodes andtypically liquid electrolyte in temporary shutters.The system operates on the same principle ascathodic protection but the current density is1000 – 2000mA/m2 (c.f. 10-20mA/m2 forcathodic protection) and the treatment for 3 to15weeks changes the concrete chemistry. Chloridesare extracted into the liquid electrolyte foreventual disposal and very high levels ofhydroxyl ions are generated at the steel.

Life and effectiveness of treatment are still beingassessed, and are likely to be structure specific interms of concrete quality, cover, reinforcementdetails, chloride content and exposure. Initialcosts are similar to cathodic protection butcontract periods may be longer.

Chloride extraction does not need permanentpower supplies. In principle, monitoring is alsonot required although in practice checks on thecorrosion condition are recommended todetermine the life of the treatment. Chlorideextraction may not provide adequate corrosioncontrol if chloride contamination continues.

vii) Realkalisation – the equivalent of chlorideextraction but used where the structural concreteis carbonated. Its description is similar to thatprovided for chloride extraction in (vi) above butthe treatment time is typically 5-15 days. Theelectrolyte is selected to assist in re-establishingthe original highly alkaline conditions within theconcrete cover, thereby controlling the corrosion.

3/2

It is not suitable for chloride contaminated or forboth chloride contaminated and carbonatedstructures.

viii) Replacement - A properly designed replacementelement or structure has advantages but also hasfinancial and logistical disadvantages.

ix) Corrosion Inhibitors – for information on the lifeand effectiveness of corrosion inhibitorsreference should be made to BA 57 (DMRBVol.1.3.8).

x) Corrosion/Durability Monitoring - may beinstalled to monitor the ingress of chlorides andthe initiation of corrosion of structures in harshenvironments or to monitor the performance aftermany of the above treatments, including donothing, and around the edges of repairs orconcrete replacement. Corrosion monitoring hasalso been installed to monitor new structures.

Site Survey

3.5 All areas of the structure requiring cathodicprotection are checked for delamination of the concretecover. Defects such as cracks, honeycombing, or poorconstruction joints that permit significant waterpenetration and could impair the effectiveness of thecathodic protection, are recorded.

Chloride content, in increments of depth through thecover zone and past the reinforcement may be measuredat representative locations. Carbonation depthmeasurements may also be conducted at representativelocations.

Representative concrete cover and reinforcementdimensions are measured, for correlation with chlorideand carbonation measurements and to confirm thedocumentation of reinforcement quantities and location.The risk of electrical short circuits between anodes andreinforcement and with other steel such as tie wires isalso assessed.

3.6 The documentary information is assessed andsupplemented with tests to confirm the extent ofelectrical continuity within and between elements. Thisis usually carried out as part of the potential (half-cell)survey but should also be performed on a representativebasis as follows:

February 2002



a) electrical continuity between elements of thestructure within each zone of the cathodicprotection system;

b) electrical continuity of reinforcement withinelements of the structure;

c) electrical continuity of metallic items, other thanreinforcement, to the reinforcement itself.

3.7 Potential surveys of representative areas, bothdamaged and apparently undamaged, are carried outusing portable equipment. Measurements are taken,preferably on an orthogonal grid, at a maximum spacingof 500 mm.

It may not be necessary to carry out a steel/concrete/reference electrode potential survey of the entirestructure. It may be appropriate to survey in more detailthose areas where reference electrodes are planned tobe permanently installed in order to place them in themost anodic areas and other suitable locations.

Electrical continuity of the reinforcement within anysurvey area is essential and should be verified beforethe steel/concrete potential survey.

Measurements in areas identified as delaminated shouldbe treated with caution. Delaminations can producereadings inconsistent with the level of corrosion of thereinforcement.

Existing repairs are checked to ensure they are in goodcondition and are compatible with cathodic protection,ie capable of passing current to the reinforcement.

Merits of cathodic protection

3.8 There are a number of merits of cathodicprotection:

• undamaged chloride contaminated or carbonatedconcrete does not require replacement; concreterepair costs are consequently minimised;

• since concrete breakout is minimised, then it islikely that temporary works such as structuralpropping during repair will also be minimised;

• concrete repair work and structural proppingfrequently requires lane closures and trafficcontrol. These costs are consequently minimised;

February 2002

• minimising concrete breakout reducesuncertainties over structural behaviour due toredistribution of stress;

• there is no need to cut behind the rebar to removechlorides. In practice this may be required, in partor whole, to ensure adequate bonding of thepatch repair material;

• cathodic protection controls corrosion for all thesteel regardless of present or future chloride levelor carbonation;

• cathodic protection can be applied to specificelements, eg cross heads, or to entire structures;

• the cathodic protection current controls corrosionin areas adjacent to concrete repairs that wouldnormally require removal if only patch repairingwere carried out;

• the requirement for regular monitoring of acathodic protection system is usually regarded asan argument against cathodic protection.However, it means that a continuous assessmentof the corrosion condition is available;

• the integration of continuous corrosion conditionmonitoring can be an important benefit forcritical structures and for structures in severeexposure conditions. Costs of continuousmonitoring, inspection and control are low(typically less than 5 man-days per year).

Cathodic protection of Critical/Sensitive Elements

3.9 Particular caution and attention to detail isrequired when considering the application of cathodicprotection to critical or sensitive elements such asconcrete hinges or half joints.

The existing condition and structural performance ofthese elements must be fully assessed in order todetermine that controlling corrosion by the applicationof cathodic protection will result in continued safeoperation. Further, as these elements tend to have verycomplex reinforcement details the cathodic protectiondesign, in particular in respect of distribution of currentand the adequate provision of performance monitoringdevices, requires careful attention.

It is recommended that such systems should be thesubject of a fully independent cathodic protection andstructural design check and certification. (See Clause5.2).

3/3



Cautionary Notes for Cathodic Protection

3.10 Cathodic protection requires good electricalcontinuity of the reinforcement. Fusion bonded epoxy-coated reinforcement is difficult to cathodically protectunless the reinforcement cage has been madeelectrically continuous prior to coating. Any otherorganic coatings would have similar problems. Metalliccoatings on the reinforcement (eg galvanising) willchange the requirements for cathodic protection controland would need proper evaluation.

3.11 There is a theoretical risk that the alkaligenerated at the reinforcement by the cathodic reactioncould exacerbate any tendency for alkali silica reactionin the aggregates. BS EN 12696 states “Cathodicprotection applied in accordance with this standard hasbeen demonstrated to have no influence on alkali silicareaction/alkali aggregate reaction (ASR/AAR).”However, if ASR/AAR is a principal cause ofdeterioration and not reinforcement corrosion, cathodicprotection alone will not be an appropriate solution.

3.12 Cathodic protection works by changing the steel/concrete potential which is measured between anembedded reference electrode and the steel. If thepotential becomes too negative, the cathodic reactiongenerates excessive hydrogen. Prestressing steel may besensitive to hydrogen embrittlement and, due to thehigh tensile loading of prestressing members, failurecan be catastrophic. The risk of hydrogen embrittlementis even more acute if there is any corrosion of theprestressed steel as pits or notches form initiation sitesfor failure and are more susceptible to hydrogenevolution and as initiation sites for failure.

It is not currently recommended to apply cathodicprotection to any prestressed or post-tensioned concreteelements. If there are no other viable remediationoptions, and provided the tendons are in good conditionwith no corrosion, then cathodic protection may beconsidered. Such applications should be provided withthe necessary sub-division of anodes into small zoneswith detailed performance monitoring devices, inparticular reference electrodes, in order that excessivecathodic protection is avoided. It is recommended thatsuch systems should be the subject of a fullyindependent cathodic protection and structural designcheck and certification (See Clause 5.2).

3.13 Cathodic protection applied in accordance withthe procedures described in BS EN 12696 to reinforcedconcrete has been demonstrated to have no adverseeffects on the bond between reinforcement andconcrete.

February 20023/4


Chapter 4Cathodic Protection System Options

N SYSTEM OPTIONS
4. CATHODIC PROTECTIO
General

4.1 Alternative cathodic protection systems aresummarised in Chapter 2.

Impressed Current Systems versus Galvanic AnodeSystems

4.2 The majority of cathodic protection systemsapplied to reinforced concrete internationally and,particularly in the UK, are impressed current systemswhere the electrical d.c. power supply is a mainspowered transformer-rectifier or similar power supply.These systems can be controlled to accommodatevariations in exposure conditions and future chloridecontamination.

4.3 Galvanic anode systems have been used inrelatively minor trials in the UK and are reported to bequite successful in trials in the USA, particularly in hothumid, marine, conditions where the electricalresistivity of the concrete will be low. It is consideredthat more extensive performance data are required forgalvanic anode systems applied to atmosphericallyexposed reinforced concrete in UK conditions beforetheir use is recommended for highway structures in theUK.

Power Supplies

4.4 Typically the power supplies for cathodicprotection systems are rated at 0-12 volts for conductivecoating or mesh anode systems and 0-24 volts fordiscrete anode systems or for special applications wherea high resistance between anode and reinforcement isanticipated.

4.5 The most common power supply for the lowvoltage d.c. requirement is a transformer-rectifier, itselfsupplied from the single-phase mains distributionsystem. Switched mode power supplies are also widelyused. The d.c. power supply will normally also be usedas a point at which the performance monitoring systemis terminated for either local or remote monitoring.

February 2002

The d.c. power supply may be controlled:

• manually;

• remotely via a modem;

• a combination of both.

4.6 Where a.c. power is not available solar panelsand wind generators can provide the necessary power.

Anode Systems

4.7 There are a variety of anode systems that aresummarised in Chapter 2. In addition to those anodesystems described in this Advice Note there areemerging systems. Where such systems are proposed,evidence should be provided to demonstrate adequateperformance and a high probability of achieving thedesired design life. This evidence should includeproperly researched and monitored acceleratedlaboratory testing and field trials. Field trials shouldincorporate a minimum of two UK winters and shouldbe applied to a civil engineering structure exposed toconditions that are representative of the environment ofthe highway structure being considered as a recipient ofthe new anode system.

4.8 Where the foundations are either buried orimmersed in sea or brackish water, it may beappropriate to apply cathodic protection using buried orimmersed anodes remote from the foundations. Theseanodes are of a significantly lower cost for materialsupply and installation than the anodes in Table 1,which are specifically designed for installation into andonto concrete.

Galvanic anodes of magnesium (normally for soilapplications), zinc or aluminium alloys (normally forsea water applications) or impressed current anodes(high silicon cast iron, mixed metal oxide coatedtitanium or magnetite), have a long and proven recordin the applications of cathodic protection to steelexposed to soils and waters.

4.9 Typically these anode systems in soils or waterscan be designed with an anticipated life in the range20-40 years, but they are easier to replace than anodesinstalled in or on concrete. Expressed as a cost persquare metre of concrete being protected their cost

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would be typically in the range £5-£15 per m2 at 2000costs.

Other Life Determining Factors

4.10 By appropriate anode selection and design it ispossible to provide cathodic protection systems withdesign lives in the range 10 to 120 years.

4.11 Many cathodic protection systems, particularlythose using mixed metal oxide coated titanium mesh orgrid anodes encased in cementitious overlays, willencase all cabling within the concrete and therebyprotect the equipment from environmental damage and,in particular, vandalism.

The environment for cables will be particularly extremewith the concrete being highly alkaline. Also the anodicreaction products generate acidic conditions adjacent tothe anodes, requiring careful selection of sheathmaterials, particularly if the cable is in close proximityto the anode.

4.12 Cabling systems installed on the externalsurfaces of highway structures in cable trays or similarcable management systems have been vulnerable tovandalism and present maintenance problems.Wherever possible, cables should be buried in chaseswithin the concrete for protection.

4.13 Transformer-rectifiers, monitoring systems andtheir enclosures are vulnerable to damage and toatmospheric corrosion. Their specification and locationshould aim to minimise the risks of vandalism andmechanical damage and the enclosure should provideenvironmental protection against the worst caseenvironment in accordance with IEC 529.

The enclosure materials and/or corrosion protectiontreatment should provide a minimum of 10 years to firstmaintenance in respect of atmospheric corrosion. It isprobably reasonable to anticipate a 25 year life beforereplacement of the electrical and electronic systems thatcomprise the transformer-rectifiers and monitoringsystems.

Performance Monitoring Systems

4.14 As outlined in Chapter 2, the performance ofcathodic protection systems is monitored by measuringthe effects of the cathodic protection current flow on:

a

b

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) steel/concrete potential measured with respect toreference electrodes installed in the concreteadjacent to the steel;

) steel/concrete potential measured with respect toreference electrodes or (less accurate) probesinstalled in the concrete and the magnitude ofpotential decay with time after the cathodicprotection system is switched off.

.15 Reference electrodes or probes should all beelected on the basis of sufficient documentary datarom the manufacturers or system suppliers toemonstrate their accuracy, their functional ability andheir longevity as required within the cathodicrotection system.

uitable Reference Electrodes are:

silver/silver chloride/0.5M potassium chloridegel electrode

(Ag/AgCl/0.5M KCl)

manganese/manganese dioxide/0.5M potassiumhydroxide electrode

(Mn/MnO2/0.5M KOH).

.16 Generally, accurate reference electrodes mayave a life in the range 10-20 years. Potentialeasuring probes (sometimes called pseudo electrodes)ay be less accurate but have a life expectancy well in

xcess of 20 years.

.17 Steel/concrete/reference electrode potentialeasurements taken with the cathodic protection

urrent switched ON will contain errors due to theoltage established by the current (I) flowing throughhe resistive (R) concrete and films on theeinforcement. These are termed IR drop errors. Tovoid these errors the steel/concrete potential iseasured “instant off” typically between 0.1 seconds,

nd 0.5 seconds after switching OFF the cathodicrotection current.

he absolute value of the steel/concrete potential is onef the criteria in BS EN 12696, as well as the decayrom that value over a period of 24 hours or longer withhe cathodic protection current switched OFF, as in.10.

.18 The voltage or current signals from theerformance monitoring reference electrodes or probesnd their associated connections to the steel

reinforcement can be monitored manually, locally at thestructure or can be data logged either locally or via a

February 2002



modem interface for remote interrogation and datacollection.

4.19 Remotely controlled distributed d.c. powersupplies typically incorporate remote monitoring andcontrol as an integrated part of their package. The largermulti-channelled systems in centralised enclosures cantypically be provided with or without remotemonitoring.

4.20 Remotely controlled and/or remotely monitoredcathodic protection equipment can transmit their dataand be commanded with control instructions via the fullrange of communication networks including hardwiredtelephone, wireless (mobile) telephone, e-mail, radio,etc. Consideration should be given to possibleextensions of the cathodic protection system andassociated communication network and the relativemerits of simple stand-alone systems or extensivenetworked systems. Competitive procurement issuesmay be complex in this sector.

4.21 Typical costs of a remote monitoring and controlsystem are presented in Table 1.

Cathodic Protection of New or UndamagedStructures

4.22 Cathodic protection can be applied to reinforcingsteel in concrete that is not presently corroding toprevent depassivation and corrosion when chloridelevels at the steel concrete interface eventually becomesufficiently high. This is sometimes referred to as‘cathodic prevention’.

4.23 The use of cathodic prevention can be consideredat construction for any structure where the exposureconditions to chlorides will mean that significantcorrosion will occur during the design life of thestructure. This might include the tidal zones of marinehighway support structures or tunnels where theexternal ground water or estuarine conditions are saline.As yet it has not been extensively used in the UK but itis increasingly used in regions with severe durabilityproblems.

4.24 Cathodic prevention, particularly if installed atthe time of construction, is likely to be significantlylower in cost than cathodic protection installed duringthe service life of a structure.

4.25 Where chloride contamination due to exposure isconsidered to be sufficient to result in corrosion damageduring the design life of the structure, but does notpresently justify the installation of a cathodic

pgmtcp

February 2002

revention system at construction, consideration may beiven to the installation of a corrosion/durabilityonitoring system. This would give early warning of

he ingress of chlorides, and the ability to plan aathodic prevention system installation or otherreventative maintenance.

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ROCUREMENT

Chapter 5Design Process and Procurement

Procurement and Design Routes

5.1 A number of established routes are available forthe design and procurement of cathodic protectionsystems for reinforced concrete. The main alternativescan be outlined as follows:

i) Full and detailed design and specification by theClient’s Consultant, with no design responsibilityupon the Contractor. Such an approach may beappropriate for stages of a phased repairprogramme where consistency and continuity ofdesign is considered essential.

Novel and innovative installations, where the risk oftechnical and practical problems is higher, may alsobenefit from this approach.

A disadvantage of this approach is that the experienceof the Contractor is excluded until the installation phaseof the project.

ii) Detailed performance specification and outlinecathodic protection design by the Client’sConsultant, with the Contractor responsible forthe detailed system design. This is a widely usedapproach and has many advantages bothtechnically and practically.

An advantage of this approach is that the experienceand ingenuity of the Contractor can influence the finaldesign, typically subject to checking and approval bythe Client.

iii) Detailed performance specification and outlinedesign by the Client’s Consultant with restricteddesign scope for the Contractor, for example,through the exclusion of certain anode options.This approach can allow the experience of theContractor to contribute to the design whilecontrolling particular aspects of the installationand as such may be seen to have many of theadvantages of both i) and ii).

iv) Full and detailed specification and design by theContractor as part of a design and build package.In principle, this approach should allowprocurement procedures to be simplified.

5. DESIGN PROCESS AND P

February 2002

As with all procurement and design routes, theexperience and capabilities of the personnel involvedshould be carefully controlled and monitored. See 5.3.

Design Review/Certification

5.2 On completion of the detailed cathodic protectiondesign, irrespective of the procurement route, theprincipal aspects of the design should be subject toreview by appropriately experienced personnel. See 5.3.

As a minimum, a design review should include thefollowing:

i) Review of existing data as employed by thedesigner during the selection and design of thecathodic protection system.

ii) Review of design methodology and comparisonwith specification and any outline system design.

iii) Numerical checks of critical and other selecteddesign calculations, including evaluation of anyassumptions made.

iv) Preparation of concise report, detailing thefindings from i) - iii) above and stating clearlyhow the design conforms to the specification.The report should also highlight any technical orpractical concerns that have been identified.

In certain cases, the contract will demand thecompletion of a formal certificated independent designcheck, clearly stating that the design is consistent withthe specification and highlighting any aspects of thedesign that are not in accordance with the specification.

Personnel

5.3 Due to the specialised nature of cathodicprotection, and its design, specification and installationfor reinforced concrete structures, it is essential that theexperience and capabilities of key personnel areestablished prior to any works proceeding.

All works resulting in the production of a specification,system design (outline or detailed), the installation,commissioning and operation should be overseen byexperienced personnel with at least one of thefollowing:

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Chapter 5Design Process and Procurement

i) An appropriate degree plus a minimum of threeyear’s responsible experience in the design andspecification or installation and operation (asappropriate) of cathodic protection systems forreinforced concrete.

ii) Professional Membership in the Institute ofCorrosion or Certificated as a CathodicProtection Specialist or Corrosion Specialist ofNACE International plus a minimum of threeyears’ responsible experience in the design andspecification or installation and operation (asappropriate) of cathodic protection systems forreinforced concrete.

In all cases, evidence of qualifications, experience anddetails of previously installed and operational cathodicprotection systems should be sought prior to theapproval of specialist personnel.

Where an organisation cannot provide such personnelfrom their own permanent staff, it is acceptable for anappropriate external specialist or company to bebrought in as a specialist consultant or contractor.

It is common practice for the Consultant and Contractorfor cathodic protection contracts to be members of theCorrosion Prevention Association (CPA).

Quality Management Systems

5.4 The various, well-defined stages associated withthe specification, design, installation and operation ofcathodic protection systems for reinforced concretestructures can be readily integrated into an appropriateQuality Management System. Such systems are widelyoperated by the majority of Consultants and Contractors(eg under BS EN ISO 9000).

Quality Management System requirements should bedefined in the contract. Appropriate documents mayinclude:

i) Quality Plans;

ii) Design/Calculation Sheet;

iii) Design Review/Certification;

iv) Method Statements and Material Data Sheets;

v) Installation Test Records;

v

v

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i) Commissioning and PerformanceDocumentation;

ii) As-Built Drawings of concrete repairs and thecathodic protection systems.

February 2002


Chapter 6Installation

Removal of Damaged Concrete/Old Repairs

General

6.1 The installation should be overseen by personnelwith the experience and expertise detailed in 5.3. Theinstallation will incorporate specialist trade skills whichmay include concrete repair, surface preparation,coating application, sprayed concrete application andspecialist cathodic protection component installationskills. These skills should be demonstrated anddocumented to appropriate levels for both tradeoperatives and site supervisors. In the planning andexecution of the work all the normal constructionindustry requirements regarding safety, riskassessments, safety plans and environmentalassessments should be properly addressed.

6.2 The original concrete and previous repairs arerequired to conduct the electrical current from theanode to the steel reinforcement. In order to achieve auniform current distribution the concrete needs to besound and the electrical resistivity of the repairs shouldbe within the range 50% - 200% of that of the parentconcrete.

6.3 All areas of unsuitable or defective concreteidentified during the survey are removed and anyexposed reinforcement prepared by removing all loosecorrosion scale, and if necessary replaced.

It is not necessary to remove sound but chloridecontaminated or carbonated concrete.

Electrical Continuity of Steel Reinforcement

6.4 Electrical continuity checks are carried out byeither measurements of electrical resistance or potentialdifference, at representative locations and for allreinforcement in concrete repair areas, within thevicinity of the cathodic protection system.

These checks are to ensure electrical continuity withinthe reinforcement. If discontinuity is found appropriateelectrical bonding should be carried out.

6.5 If the structure incorporates other metalliccomponents within the area of the cathodic protectionsystem or adjacent to the cathodic protection system(eg drainage pipes, brackets, dowel bars, bearings), it is

6. INSTALLATION

February 2002

necessary to either bond the metallic components to thecathodic protection system negative (reinforcement), orto electrically isolate the metal from the systemnegative.

Installation of Negative Connection andPerformance Monitoring Equipment

6.6 Negative connections are required between thereinforcement and the transformer-rectifier. A minimumnumber of two negative connections should be made ineach zone.

6.7 Reference electrodes are installed to enable themeasurement of the potential of the steel/concreteinterface. Reference electrodes should be installed atanodic locations in each zone.

6.8 All electrodes and probes should be installedwithin a concrete breakout or drilled hole that does notdisturb or affect the surrounding concrete around theelement of reinforcement to be measured, iereinforcement should NOT be exposed within 0.5m ofthe electrode, probe or coupon.

Concrete Repairs

6.9 Concrete repairs are required to reinstate theconcrete to its original profile where cracking orspalling has occurred or where the previous repairs areunsuitable.

It is not necessary to remove sound but chloridecontaminated or carbonated concrete.

6.10 Standard concrete repair techniques based onbest practice guidance and the manufacturer’srecommendations should be used to reinstate theconcrete. The concrete repair materials should beselected for their compatibility with cathodic protectionsystems as in 6.2 above.

The steel reinforcement should not be primed and nobonding agents should be used.

6.11 Where an anode system is being applied to thesurface of the concrete, repairs should be cured withoutthe use of a curing membrane.

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Anode Installation

6.12 The concrete should be prepared prior to theinstallation of the anode. For surface mounted anodesthe concrete should be adequately prepared to ensure agood physical bond between the concrete and the anodeor its overlay. Surface preparation should present aclean, sound, dust free surface of suitable roughnessand exposure of aggregate for the various anode oroverlay types.

6.13 Internal anodes should be inserted into chases orholes cut into the concrete. Chases may need to be gritblasted to provide a physical key for the cementitiousbackfill. Holes do not normally require any furtherpreparation.

6.14 During the installation of anodes it is importantto check for any possible electrical short circuitsbetween the anode and the steel reinforcement and thatanode/steel spacing is adequate.

6.15 The concrete should be inspected to identify anytie wire or steel which may short-circuit to the anode.Particular attention should also be given to any soffitareas where there may be loose tie wire etc. on thesurface.

6.16 Conductive coating anodes may be spray appliedor hand applied (roller or brush). The anodes have aprimary anode which distributes the current evenly tothe anode surface. The primary anode is usually a metalwire or ribbon which is either fixed to the concretesurface prior to the anode application or is incorporatedinto the coating film.

6.17 Titanium mesh or grid anodes should be fixed tothe concrete surface using plastic fasteners. Anodesections are interconnected with spot welded titaniumstrip which may also be used as current distributors.The anode should be encapsulated in a cementitiousoverlay that can be either spray applied or cast.

6.18 Internal anodes should be embedded in concretechases or holes using cementitious material or graphitebackfill.

6.19 A minimum number of two anode/cableconnections should be provided in each anode zone.

6.20 The correct installation of the anode is essentialfor the success of the cathodic protection system. Itshould only be undertaken by appropriately trainedpersonnel.

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Electrical Installation

6.21 All power supplies, monitoring systems andcables should be installed to provide adequateprotection from vandalism and the environment. Wherethe risk of vandalism is high, cabling should beembedded within the concrete surface.

6.22 Prior to energising, the system should be tested toprove the function and polarity of all circuits. Thesetests should be documented.

Commissioning

6.23 Before energising, the “as found” conditionshould be established by measurement of steel/concretepotentials at permanently embedded referenceelectrodes.

6.24 Initial energising should be at low current andshould be immediately followed by testing todemonstrate that all zones are operating correctly.

6.25 The system should then be adjusted to a suitablelevel of current and allowed to operate for a periodbefore Performance Monitoring (typically 28 days).

Records

6.26 During the installation the cathodic protectioncontractor must maintain adequate and accuraterecords. The documentation shall comprise thefollowing:

i) Installation Record Drawings

ii) Test Reports and Data

iii) Certification of materials

iv) COSHH information

The Installation Record Drawings shall show allcathode (including reinforcement bonding positions),anode and connections, reference electrode, corrosionrate probes, cabling layouts and junction box positions.

The records will form part of the Maintenance Manualfor the structure.

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Training

6.27 Before the completion of the Contract,arrangements should be made to provide training forstaff of the Maintenance Organisations for ongoingmanagement of the cathodic protection system. In somecases it may be possible or desirable to retain specialistadvisers to manage the system. Consideration must begiven to the procurement of such services.

February 2002 6/3


MENT, INSPECTION

Chapter 7Performance Assessment, Inspection and Maintenance

7.1 The intervals and procedures for routineinspection and testing vary from one cathodicprotection system to another dependant upon thestructure, the cathodic protection system type, thereliability of power supplies, the environment and thevulnerability to damage.

7.2 Those systems provided with electronically datalogged or electronically data transmitted performancemonitoring systems may require less frequent physicalinspection as the routine testing can be undertakenautomatically.

7.3 Consideration can be given to extending theintervals between routine inspection and testing if nofaults, damage or significant variation in systemperformance are indicated by successive inspections/tests.

7.4 Routine inspection procedures are typically asfollows:

a) Function Check comprising:

• confirmation that all systems arefunctioning

• measurement of output voltage and currentto each zone of the cathodic protectionsystem

• assessment of data.

Typically, the Function Check should beundertaken monthly in the first year of operationand, subject to satisfactory performance,thereafter at 3 monthly intervals.

b) Performance Monitoring comprising:

• measurement of “instant OFF” IR errorfree polarised potentials

• measurement of potential decay over aperiod of 24 hours or longer

• measurement of parameters from any othersensors installed as part of the performancemonitoring system

7. PERFORMANCE ASSESSAND MAINTENANCE

February 2002

• limited visual inspection

• assessment of data

• adjustment of current output.

Typically the Performance Monitoring should beundertaken at 3 monthly intervals in the first yearof operation and, subject to satisfactoryperformance and review at 6 monthly to 12monthly intervals thereafter.

c) System Review comprising:

• a review of all test data and inspectionrecords since the previous System Review

• full visual inspection

• preparation of a System Review reportincorporating recommendations for anychanges to the operation and maintenanceor system review intervals and procedures.Cathodic protection systems that areoperating in a reliable and stable mannercan benefit from the reduced costs ofextending the intervals between bothFunction Checks and PerformanceMonitoring.

Typically, the System Review should beundertaken annually.

7.5 Maintenance of the cathodic protection system isgenerally restricted to fault finding, replacement ofelectrical components within the d.c. power supplyunits, if required, repairs to cabling, trunking, conduit,junction boxes, repairs to conductive coating anodesand general maintenance to the power supply enclosure.See Table 1 for typical anode system life.

7.6 The requirement of cathodic protection systemsto receive the routine inspection procedures describedin Clause 7.4 must be addressed in the continuingmanagement requirements of structures provided withcathodic protection. Both Function Check andPerformance Monitoring work can be undertaken byproperly trained technician grade personnel. Local staffcan be trained for this work and this is often a

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Chapter 7Performance Assessment, Inspection and Maintenance

requirement incorporated into a cathodic protectioninstallation and commissioning contract.

Remotely monitored systems do not need to be visitedfor function checks. The maintenance proceduresshould be fully documented in maintenance andoperation manuals.

The System Review activity should be undertaken bypersonnel who are appropriately expert and experiencedas in Clause 5.3.

In the event of a cathodic protection system beingadopted by different Maintenance Organisations oroperators, the records and manuals should enable thecontinued satisfactory operation of the system.

February 20027/2


February 2002

1. BS EN 12696: 2000 Cathodic Protection of Steelin Concrete. British Standards Institution, 2000.

2. CPA Corporate Members Directory.ISBN: 0 9525190 5 4.Web-Site: www.corrosionprevention.org.uk

3. BS 7361: Cathodic Protection. Part 1: Code ofPractice for Land and Marine Applications,British Standards Institution, 1991.

4. “Cathodic Protection of Reinforced Concrete –Status Report”, Corrosion Prevention Association(formerly SCPRC), Report No. 001.95, 1995.

5. Boam, K.J., Unwin, J. “The Midland Links –A Maintenance Strategy” Institution of Highways& Transportation, National Workshop - NewConcepts for Management of HighwayStructures, Leamington Spa, pp 59 to 73, 1990.

6. Unwin, J., Hall, R.J. “Development ofMaintenance Strategies for Elevated MotorwayStructures” Proc. 5th Intl. Conf. On StructuralFaults and Repair, Ed. Prof. M.C. Forde.Vol. 1 pp 23 to 32., 1993.

7. CPA Monographs as listed in Reference 2 above.

8. DMRB Standard BD43 ‘Impregnation ofconcrete highway structures’.

9. DMRB Advice Note BA57 ‘Design fordurability’.

10. MCHW Volume 1 ‘Specification for HighwayWorks’.

11. MCHW Volume 2 ‘Notes for Guidance on theSpecification for Highway Works’.

8. BIBLIOGRAPHY

Chapter 8Bibliography

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February 2002 9/1

9. ENQUIRIES

All technical enquiries or comments on this Advice Note should be sent in writing as appropriate to:

Head of Civil EngineeringThe Highways AgencySt Christopher HouseSouthwark Street G BOWSKILLLondon SE1 0TE Head of Civil Engineering

Chief Road EngineerScottish Executive Development DepartmentVictoria QuayEdinburgh J HOWISONEH6 6QQ Chief Road Engineer

Chief Highway EngineerThe National Assembly for WalesCynulliad Cenedlaethol CymruCrown BuildingsCathays Park J R REESCardiff CF10 3NQ Chief Highway Engineer

Assistant Director of EngineeringDepartment for Regional DevelopmentRoads ServiceClarence Court10-18 Adelaide Street D O’HAGANBelfast BT2 8GB Assistant Director of Engineering

Chapter 9Enquiries

corrections within design manual for roads · pdf filecorrections within design manual for...

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