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c HongKongGovernment

Firstpublished,July1994.

Preparedby:

CivilEngineeringDepartment, CivilEngineeringBuilding,

101,PrincessMargaretRoad, Homantin,Kowloon, HongKong.

StandingCommitteeonConcreteTechnologymembers:

R.H.Pilling(Chairman)W.M.ChanC.S.ChungY.L.LeeW.C.LeungK.C.NgP.J.OsborneH.W.PangP.L.PangC.W.PoonW.Y.Tang

Thispublicationisavailablefrom:

GovernmentPublicationsCentre, GeneralPostOfficeBuilding, GroundFloor, ConnaughtPlace, HongKong.

Overseasordersshouldbeplacedwith:

PublicationsSalesSection, InformationServicesDepartment, 4thFloor,BeaconsfieldHouse, QueensRoadCentral, HongKong.

PriceinHongKong:HK$42 Priceoverseas:US$14(includingsurfacepostage)

Cheques,bankdraftsormoneyordersmustbepayabletoHONGKONGGOVERNMENT

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FOREWORD

This Model Specification lays down the quality of materials, thestandardsofworkmanship, the testingmethodsand the acceptancecriteriafor protective coatings for concrete, appropriate to various aggressiveenvironments and conditions, in works undertaken for the Hong KongGovernment. It has been prepared in such a manner that the clausescontainedhereinshouldbeusedasmodelclausesforthepreparationofaParticularSpecificationandshouldbemodifiedoraddedtowherenecessarytosuittherequirementsofindividualprojects.

InordertoassistinthepreparationofaParticularSpecification,notesareprovidedonadjacentpagesagainstsomeoftheclausestoamplifythe

intentoftheseclauses.This Model Specification was produced under a consultancy study

monitoredby the StandingCommittee on Concrete Technology, with thefinaleditingandproductioncarriedoutbytheStandardsUnitoftheCivilEngineeringDepartment.

July1994

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CONTENTS

PageNo.

GENERAL

01 Abbreviations 13

SUBMISSIONS

02 Supplyofinformation 15 03 Codingsystem 15 04 Storagelife 15 05 Methodofusingpaintcomponents 15

06 Surfacepreparationofconcrete 15 07 Dryfilmthicknessandcoverage 15 08 Overcoating 17 09 Physicalproperties 17 10 Durability 17 11 Healthandsafety 17 12 Maintenance 19

GENERALCONCRETECOATINGREQUIREMENTS

13 Surfacepreparationforuncoatedconcrete 21 14 Surfacepreparationforpaintedconcrete 21 15 Coatingapplicationfordryconcretesurfaces 23 16 Coatingapplicationfordampconcretesurfaces 25 17 Paintfinish 27 18 Qualitycontrolonsite 27

SPECIFICREQUIREMENTSFOR

CARBONATIONRESISTANCE

19 Newconstructionandolderconstruction 29 20 Backpressureactingoncoatings 35 21 Concretesubjecttograffiti 35

SPECIFICREQUIREMENTSFORCHLORIDE

RESISTANCE

22 Concretesubjecttochloridesprayandcarbonation 35

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PageNo.

23 Concretesubjecttocyclicimmersioninseawater 35

24 Concretewaterretainingstructuressubjecttosaltspray 37 25 Concretesubjecttochlorideback-penetrationfromsoil 37

SPECIFICREQUIREMENTSFORCHEMICAL

RESISTANCE

26 Resistancetosewage 37 27 Resistancetohighlyaggressivechemicals 39


ACTIVE/DYNAMICCRACKBRIDGING

RESISTANCE

28 Concretesubjecttoactivecracks 39

SPECIFICREQUIREMENTSFORTIDALWORK

29 Concretesubjecttocyclicimmersioninseawater 39 30 Wetconcretesurfaces 41

APPENDICES

APPENDIX1 45

DETERMINATIONOFTHEWATERVAPOUR

DIFFUSIONRESISTANCEOFCOATINGS

1.1 Scope 45 1.2 Testsubstrate 45 1.3 Procedure:preparationofspecimens 45 1.4 Procedure:determinationofwatervapourtransmissionrate 45 1.5 Calculation 46 1.6 Reportingofresults 47

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PageNo.

APPENDIX2 49

DETERMINATIONOFTHECARBONDIOXIDE


2.1 Scope 49 2.2 Testsubstrate 49 2.3 Equipment 49 2.4 Procedure:preparationofspecimens 49 2.5 Procedure:determinationofgasflowrate 50 2.6 Calculation 50

2.7 Reportingofresults 52

APPENDIX3 55

DETERMINATIONOFTHEWEATHERING

RESISTANCEOFCOATINGS

3.1 Scope 55 3.2 Testsubstrate 55

3.3 Equipment 55 3.4 Method 55 3.5 Reportingofresults 56

APPENDIX4 57

DETERMINATIONOFTHESALTSPRAY


4.1 Scope 57 4.2 Materials 57 4.3 Procedure:preparationofspecimens 57 4.4 Procedure:determinationofsaltsprayresistance 59 4.5 Reportingofresults 59

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PageNo.

APPENDIX5 61

DETERMINATIONOFTHESALTWATER

IMMERSIONRESISTANCEOFCOATINGS

5.1 Scope 61 5.2 Materials 61 5.3 Procedure:preparationofspecimens 61 5.4 Procedure:determinationofsaltwaterimmersionresistance 63 5.5 Reportingofresults 63

APPENDIX6 65

DETERMINATIONOFTHEDYNAMICCRACK

BRIDGINGRESISTANCEOFCOATINGS

6.1 Scope 65 6.2 Materials 65 6.3 Equipment 65 6.4 Procedure:preparationofspecimens 65

6.5 Procedure:determinationofcrack-bridgingresistance 66 6.6 Reportingofresults 67

APPENDIX7 71

DETERMINATIONOFTHEWATER

PERMEABILITYRESISTANCEOFCOATINGS

7.1 Scope 71 7.2 Materials 71 7.3 Equipment 71 7.4 Procedure:preparationofspecimens 72 7.5 Procedure:determinationofwaterpermeability

bylaboratorytestrig 73 7.6 Procedure:determinationofwaterpermeability

byCLAMTester 74 7.7 Reportingofresults 74

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PageNo.

APPENDIX8 77

DETERMINATIONOFTHEBOND

STRENGTHOFCOATINGS

8.1 Scope 77 8.2 Materials 77 8.3 Equipment 77 8.4 Procedure:preparationofspecimens 77 8.5 Procedure:determinationofbondstrength 78 8.6 Reportingofresults 79

APPENDIX9 83

DETERMINATIONOFTHERESISTANCE

TOAGGRESSIVELIQUIDSOFCOATINGS

9.1 Scope 83 9.2 Materials 83 9.3 Procedure:preparationofspecimens 83

9.4 Procedure:determinationofresistancetoaggressive liquids 84 9.5 Reportingofresults 85

APPENDIX10 87

DETERMINATIONOFWATERUPTAKE

OFCOATINGS

10.1 Scope 87 10.2 Materials 87 10.3 Procedure:preparationofspecimens 87 10.4 Procedure:determinationofwateruptake 88 10.5 Reportingofresults 89

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PageNo.

APPENDIX11 91

DETERMINATIONOFTHEIMPACT


11.1 Scope 91 11.2 Materials 91 11.3 Equipment 91 11.4 Procedure:preparationofspecimens 91 11.5 Procedure:determinationofimpactresistance 92 11.6 Reportingofresults 93

APPENDIX12 97

DETERMINATIONOFTHEALGAE


12.1 Scope 97 12.2 Materials 97 12.3 Apparatus 97

12.4 Procedure:preparationofspecimens 97 12.5 Procedure:determinationofalgaeresistance 98 12.6 Reportingofresults 98

APPENDIX13 101

METHODSFORTHEANALYSISOFCOATINGSAMPLES

13.1 Scope 101 13.2 Method:determinationofvolatilecontent 101

13.3 Method:determinationoffinenessofgrind 101 13.4 Method:determinationofviscosity 101 13.5 Method:determinationofspecificgravity 101 13.6 AdditionalTesting 101

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PageNo.

APPENDIX14 103

METHODSFORCHECKINGTHECONTINUITYOF

FILMFORMINGCOATINGSONCONCRETE

14.114.214.3

ScopeMethod:determinationofthicknessMethod:determinationofcontinuity

103103103

APPENDIX15 105

SIMPLEMETHODFORCHECKINGTHEADHESION

OFFILMFORMINGCOATINGSONCONCRETE

15.115.2

ScopeMethod:cross-cuttest

105105

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Notes

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GENERAL

Abbreviations 01 (1) AbbreviationsusedinthisSpecificationshallhavethefollowingmeanings:

ASTM :AmericanSocietyforTestingandMaterialsBS :BritishStandardSISIR :SingaporeInstituteofStandardsandIndustrial

ResearchDFT :dryfilmthicknessHOKLAS :HongKongLaboratoryAccreditationSchemeOPC :ordinaryPortlandcementPVC :polyvinylchlorideR-value :equivalentairlayerthicknessSD-value :watervapourdiffusionresistanceSBR :styrenebutadienerubberUV :ultraviolet

(2) AbbreviationsofunitsofmeasurementusedinthisSpecificationshallhavethefollowingmeanings:

oCcm

2cm3cm

cm2/sgg/Lg/cm3

g/m2

Hzkgkg/m3

kgfkgf/cm2

LL/m2

L/m3

m2m3m

mLmmmolMPa

2m sMm/smL/m2smol/cm3

:degreesCelsius:centimetre:squarecentimetre:cubiccentimetre:squarecentimetrepersecond: gram :gramperlitre:grampercubiccentimetre

:grampersquaremetre:hertz:kilogram:kilogrampercubicmetre:kilogramforce:kilogramforcepersquarecentimetre:litre:litrepersquaremetre:litrepercubicmetre:metre:squaremetre

:cubicmetre:millilitre:millimetre:molarity:megapascal:squaremetresecond:megaohm:metrepersecond:millilitrepersquaremetresecond:molaritypercubiccentimetre

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mol/s : molarityperseconds : secondm : micrometre% : percentage

SUBMISSIONS

Supplyof 02 Prior to the Engineer giving approval of a particularpaint type, theInformation Contractorshallsupply informationwhichwill satisfy Clauses 03to

11, and independent test certificates from a HOKLAS or similaraccreditedlaboratory,traceabletothepaintsproposed,demonstratingthat they comply with the requirements of this Specification. TheContractorshallalsosupplyinformationonthesurfacefinish,colours,chemicalproperties,weatheringresistanceunderexposuretosunlight,previousandexistingapplicationsofthepaintinHongKong.Allsuchinformationshallbeindependentlyverified;anytestsorcasehistorieson structures shall have been witnessed by an independent,accountablethird-partysuchasaHOKLASaccreditedlaboratory.

CodingSystem 03 All primers, paints and solvents to be used in the works shall beidentified by a unique coding system, relating to the batch of rawmaterialsfromwhichtheproductwasmanufacturedandthedateofmanufacture.

StorageLife 04 Storagelifeshallnormallybeaminimumofoneyear. Ifthestoragelife isknown to be shorter, the expiry date must be marked on thecontainerpriortodispatchfromthemanufacturersfactory.

Methodof 05 Preparationandapplicationtechniquesforallcomponentsofthepaint

UsingPaint systemshallbe stated.Thisinformationshall includethemethodsofComponents mixingtobeusedandthemaximumdilutions,ifany,bysolventsor

water.

Surface 06 Recommendations for preparing the surfaces of concrete shall bePreparation given,includingthefollowing:ofConcrete

(a) theminimumage,(b) themaximummoisturecontentandmeasuringmethod,(c) the equipment to be used for preparing the concrete

surface,and

(d) thematerialssuitableforfillingdefectsintheconcrete.

DryFilm 07 TheminimumandmaximumDFTlimitsforeachcomponentoftheThickness paint system shall be given for a temperature of 27 C. TheandCoverage correspondingcoverageinL/m2shallbequotedforpreparedconcrete

surfaces typical of low strength (Grade 20) and high strength(Grade?40)concrete cured under site conditions, inorder toachieverecommendedDFTvalues.

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Notes

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Overcoating 08 Drying and overcoating times of the pretreatments and coats of thepaintsystemshallbegivenforatemperatureof27 Candarelativehumidityof80 5 %. I nf or mati on shoul d also be gi ven ont he li mitoftemperatureandhumidityatwhichpaintingworkshouldcease.

Physical

Properties

09 All components of the paint system shall be capable of uniqueidentificationsuchthatanysubstitution,dilutionoradulterationofthe

paint can be identified. The Contractor shall provide test data andmethodsoftestforthefollowingpropertiesofeachapplicableprimer,paintandsolventusedinthesystem:

(a)specificgravity,(b)volumeofsolids,(c)viscosity,(d)finenessofpigmentgrind,(e)infra-redspectography,(f)pyrolysisgaschromatographyofthebinder,(g)ashcontentat450C.

Durability 10 (1) Thesuitabilityof thecoatingforapplicationondamp,alkaline,cement-basedmaterialsshallbestated.

(2) Thedecorativelifeofthepaintshallbestated, in termsofthecolour-fastness of the finishcoat and resistance to chalking, loss ofglossandatmosphericdirtying.

(3) Thelifeofapaintsystempriortotheneedforrecoatingshallbeatleast10years.Examplesshallbecitedofwherethepaintsystemhasachievedthislife.

(4) Thepaintsystemshallbecapableofwithstandingcleaningwithhot water (in the range between 40C and 50C), detergent andscrubbing action without losing adhesion, softening or changing incolourorgloss.

Healthand

Safety

11 (1) TheContractorshallsupplyhealthandsafetydatarelatingtothestorageandapplicationofallcomponentsofthepaintsystem.Asaminimum,thechecklistcontainedinTable?1shallbecompleted.

(2) Theeffectsofsolventandvapourbuild-upontheenvironmentinthevicinityofthepaintapplicatorshallbemonitored,andthelossofvolatilesperunitareaofpaintintermsofminimumairexchangeratesinconfinedareasshallbedetermined.

(3) Thein-serviceperformanceofthepaintunderconditionsoffireshall be given, making particular reference to the surface spread offlame,andthetoxicityandopacityofcombustionproducts.

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Notes

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(4) TheContractorshallalsosupply informationonthelong termeffectsofvolatileorleachablecomponentsofthepaintsystemuponthe environment, with particular reference to leachable heavymetalcontentssuchasmercurybasedalgicidesorleaddriers.

Table1:Checklistofhealthandsafetyinformation

PRODUCTNAMEUSES

COMPOSITION

PHYSICALANDCHEMICALPROPERTIES

HEALTHHAZARDS

FIREHAZARDS

STORAGEPRECAUTIONS

TRANSPORTPRECAUTIONSHANDLING/USEPRECAUTIONS(includingadviceonpersonalprotectiveequipment)

DISPOSALPRECAUTIONS

EMERGENCYACTIONFire,spillage,firstaid

ADDITIONALINFORMATIONEcologicalhazards

RelevantregulationsAdvicetoOccupationalMedicalOfficersReferences

NAME,ADDRESSANDTELEPHONENUMBEROFSUPPLIER

REFERENCENUMBER,DATEOFISSUE

Maintenance 12 (1) The Contractor shall provide information on the methods ofpreparationtobeusedintheeventthatrecoatingofthepaintedsurfaceisrequired.

(2) TheContractorshall statewhichtypesofpaint, other thantheoriginal product, are compatible with the finish coat for recoatingpurposes.

(3) The Contractor shall provide information on the techniquewhichcanbeusedtorepairlocaldamagetothecoating,withparticularreferencetocolourandglossmatchingoffinishcoatsappliedafteratimelapseof5years.

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(4) The Contractor shall provide information on the mostappropriatetechniquesforcleaningofthefinishcoattoremovesurfacesoiling,withparticularreferencetoeaseofremovalofgraffitiorgluedposters,wherepossible,withoutdamagetotheexistingfinish.

GENERALCONCRETECOATINGREQUIREMENTS

Surface 13 (1) Surfaces to receivecoatings shall be sound,free fromlaitencePreparation and contamination suchasoils andgreases, andshall beat least 28forUncoated daysold.Concrete

(2) Theconcretesurfaceshallbepreparedbyhighpressurejettingwith potable water, either with or without added abrasive, wirebrushing or by othermeans approved by theEngineer, to provide astrong,hardsurface.

(3) Areas of contamination shall be removed by the use of

appropriate solvents, followed by thorough cleaningof the concretewithpotablewater.

(4) Shrinkagecracksofwidthlessthan0.3mm,blowholesorotherdefectsinthefinishedconcretesurfaceshallbefilledwithalevellingcompound compatible with the paint system to be applied; thecompoundshallbeknifedintodefectsandtight-trowelledto removeallsurplusmaterials.

(5) Shrinkagecracksofwidthgreater than0.3mmshallbesealedby resin injection, and movement joints shall be provided at joints

betweenconcreteandblockworkasinstructedbytheEngineer.

(6) Theprepared surfaceshall beprotected against contaminationwhenitistobeleftforperiodsofmorethanoneweekbeforecoating.

Surface 14 (1) The adhesion of existing paint layers to the concrete surfacePreparation shall be evaluated initially by a cross-cut test, in accordance withforPainted Appendix?15.Concrete

(2) Measurementsofcross-cutadhesionshallbemadeinsufficientnumberstorepresentonereadingper10?m2ofcoatedsurfaceforthefirst100?m2evaluated,thenthreereadingsper100?m2thereafter.

(3) Theadhesionofexistingpaintshallbedeemedtobesatisfactoryprovided75%ofthecross-cutsurfaceremainsattachedtotheconcreteand provided the surface is free from cracking, blistering or heavychalking.

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Notes

Clause 15

This Clause relates to applications on building structures and civil engineering structures exposed to the weather,away from the influence of marine spray or other sources of regular wetting.

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Coating

Application

forDryConcrete

Surfaces

(4) Compatibilitytestsshallbeundertakentoestablishwhetherthenewpaintwillbondtotheexistingpaint.Atrialareaof5?m2shallbeused,cleaned inaccordancewithClause?13(2),and the paintsystemappliedinaccordancewiththemanufacturersinstructions.RecordsofactualcoverageratesusedonthetrialareashallbemadeavailabletotheEngineer.After14days,pull-offtestsshallbemadeinaccordancewithAppendix?8.TheDFTshallalsobedeterminedforeachpaintlayer,tobetestedbyatravellingmicroscopeinamannersimilartothatstatedinClause1.3(6)atAppendix1.

(5) FailuretosatisfytherequirementsofClause?14(3)or14(4)willmeanthattheexistingcoatingsmustberemovedbyusinghotairorchemical strippers, and the surface finished by high pressure waterjetting with or without abrasive added, in accordance withClauses?13(2)to13(6).

15 (1) Allconcretesurfacestoreceivepaintshallbedryatthetimeofapplication. Sufficient drying time shall be allowed either after

constructionorafterwetpreparationmethods,tosatisfyeitheroneofthefollowingrequirements:

(a) Moisturemeterreadingsisconsistentlylessthan5%.

(b) There is no moisture retained behind a 1?m x 1?mpolythenesheet,tapedsecurelyontotheconcretesurfacetoformasealfor24hours.

(c) Internal humidity measurements within the concrete is?75%whenmeasuredbySeredaprobeorothermethods

approvedbytheEngineer.

(2) Priortoapplyingthepaint,atestareashallbepreparedonthestructuretobe painted,exceptwhereacompatibility testhasalreadybeenundertakeninaccordancewithClause14(4). Thecompletepaintsystem shall be applied in accordance with the manufacturersinstructions,includinganyprimersandundercoats,toanareaofnotlessthan5?m2.

(3) TheactualconsumptioninL/m2ofthevariouscoatsofthepaintsystemshallberecordedinthetrialarea,inorderthatdueallowance

maybemadeforrough,irregularorexceptionallyabsorbentconcrete.

(4) Whenthepaintsystemhascuredfor14days,atestofsurfaceadhesionshallbemadeinaccordancewithAppendix?8.Theaveragebondof3dolliestotheconcrete,viathecompletedcoatingsystem,shallbesatisfactory.AcoresampleshallbetakenfromthetestareaformeasurementoftheDFT.ShouldtheminimumandmeanDFT

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Notes

Clause 16

This Clause relates to applications on coastal works subject to marine spray.

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valuesofthecoresamplebelessthanthosespecified,thecoverageratesforthepaintshallbeproportionallyincreasedforthedurationoftheContract.

(5) If the bond strength results are not satisfactory, the concretesurfaceshallbecleanedusinghighpressurewaterjettinginaccordancewith Clause?13(2), followed by re-application and re-testing of thecoatinginaccordancewithClauses?15(1)to15(4).

(6) Coatings shall only be applied during favourable weatherperiods,whenrainfallisnotexpectedforthefollowing12hours.

(7) Thedewpointshallbeatleast5Clowerthanthetemperatureoftheconcretesurfacebeforepaintingcommences.

(8) Paintingusingwaterbasedpaintsshallnotcommencewhilsttherelativehumidityisabove85%orwhereitmaybeexpectedtoexceed90%duringthe12hourcuringperiod.

(9) Primers, undercoats and finish coats may be applied inaccordance with the manufacturers instructions using brush, roller,sprayorothertechniquetoachievethedesiredsurfacefinish.Brushapplicationofprimersisthepreferredmethod,workingthepaintintotheconcretepores.

(10) Wherebrushorrollertechniquesareused,thebrushesorrollerheads shall be used for the day only and then discarded. Theequipmentshallnotbecleanedforre-use.

(11) Where spray equipment is used, all cleaning fluid shall bepurgedfromtheequipmentusingundilutedpaintpriortopainting. Allcontaminatedpaintusedforpurgingequipmentshallbediscardedandshallnotbeusedintheworks.

(12) Except where airless spray equipment incorporating a nozzlemixingdeviceisemployedwhen two-componentmaterialsareused,eachcomponentshallbethoroughlystirredbeforemechanicalmixingofthewholeunitstogether;partbatchesshallnotbeused.

(13) For multiple coat applications, the manufacturers stated

minimumandmaximumovercoatingtimesfortheprevailingweatherconditions shall not be breached, and successive coats shall haveslightlydifferentcolourshadestoassistinachievinguniformcoverage.

Coating 16 (1) Paint for application onto damp concrete surfaces shall beApplication specifically formulated for tolerance to moisture during application,forDamp cureandinservice.ConcreteSurfaces

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Notes

Clause 17

Severe drying can be taken to be a wind velocity of 3 m/s at 27 2C and 60 5% relative humidity for 6 hours.

Clause 18

The frequency of carrying out the quality control tests listed at Appendix 13 depends on the size of the protective

coating contract or when the quality of the coating materials are suspected to have been changed.

The frequency of carrying out wet film thickness test is not fixed and is performed as required by the contractor and/orengineer to ensure adequate film thickness has been applied.

The frequency of testing of dry film thickness of the protective coating by an approved laboratory is normally 1 per 50

square metres of applied coating.

The tests outlined in Appendix 13 are used as quality control tests to compare the properties of the coatings samples

before and during coating works. The basic acceptance criteria is that the average of the results from an individual

test is equal to the properties measured before the coating work and is within the agreed standard deviation whichmay be obtained from the coating suppliers.

Responsibilities for tests and test results representation need to be specified in the Contract, e.g. 3 pull-off tests toform a sample set and one sample set per 50 m of applied coating or per production of one continuous application

shift, whichever is less.

The bond strength measured from a site test is normally slightly lower than that obtained from a laboratory test.

However, the acceptance criterion of average bond strength being above 1.2MPa mentioned in Clause 8.5(7) atAppendix 8 should not be relaxed as this should be achievable for coatings applied properly.

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(2) Allconcretesurfacestoreceivepaintshallbesurface-dryatthetimeofapplication,includinganycracksorotherdefectsthatmayholdwater.Theconcretesurfaceshallleavenomarkwhenasheetofpaleblueblottingpaperispresseduniformlyontotheconcrete.

(3) Where the requirements of Clause?16(2) cannot be satisfied,temporaryprotectionshallbeprovidedtoencasetheconcreteandpaintapplicator and prevent moisture penetration, ensuring adequateventilationisprovided.

(4) ThepaintshallbeappliedinaccordancewithClauses?15(2)to15(13).

(5) Depositsofsalt crystalswhichcollectoncoatedsurfacesmustbewashedoffwithpotablewaterandthesurfaceallowedtodry,priortoapplyingfurthercoatsofpaint.

PaintFinish 17 Allpaintsshallbefreefromcracking,wrinklingorotherdefectswhen

exposedtoseveredryingconditions.

Quality

Controlon

Site

18 (1) Prior to commencing painting works, the Contractor shallprovidesamplesofallpaintstobeusedofnotlessthanonelitreeachinsealedcontainers,fortestingbytheEngineer,oneachdeliveryofpainttosite.

(2) During theexecutionofthepaintingworks theEngineershallrandomly select samples of paint for comparison with the initialsamplesinaccordancewiththemethodsstatedinAppendix?13.

(3) TheContractorshallstoreallemptypainttinswhichhavebeenused intheWorks,alongwithsitedelivery tickets,for inspectionbytheEngineerwhoshallthenauthorizedisposalofthetins.

(4) Forcoatingssubjecttoaggressiveliquids,thereshallbenosignsofdefects,suchaspin-holes,crackingandblistering,onthesurface.The electrical continuity of the coating shall be measured inaccordancewithAppendix?14,ifinstructedbytheEngineer.

(5) Areas of coating which do not comply with the specifiedminimum DFT shall have a further coat applied to make good the

deficiency.Wherethemanufacturersmaximumovercoatingtimehasbeen exceeded, thesurfaceshall be lightly roughenedinaccordancewiththemanufacturersrecommendationspriortopaintapplication.

(6) Theadhesionofthecoatingtotheconcreteshallbecheckedatrandomlyselected locationsby thecross-cut test inaccordancewithAppendix?15. Should low adhesion befound,definedasmore than25%ofthe coatingbeingpulledaway, furtherinvestigationbydollypull-offtestingisrequired.

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NotesClause 19

The general purpose of applying anti-carbonation coatings is to protect buildings and structures directly exposed to

the atmosphere and ingress of carbon dioxide, and to satisfy aesthetic considerations.

The coating generic types expected to have good performance are acrylic, vinyl and polyurethane. The generic typesnot likely to perform well are polyethylene, epoxy, tar epoxy, chlorinated rubber, bituminous, cementitious, silicone

and silicate.

The recommended R-values of coating systems for different concrete grades for both new and older construction are :

(a) New Construction Concrete R-Value

Grade (m)

15 150

20 10025 50

35 2545 25

The R-values quoted are designed to prevent the carbonation front reaching the steel reinforcement in a 60year life cycle, assuming the cover is not less than 25 mm. Where the cover is less than 25 mm, the R-value

may need to be increased to achieve the 60 year life.

(b) Older Construction Concrete R-Value

Grade (m)

15 30020 300

25 20035 10045 25

The R-values for old concrete have been calculated for a 5 year old structure, carbonating rapidly. The R-valueshould limit further carbonation of the concrete from its present level (x mm) to (x + 5 mm) in a further 55

years.

In considering older construction, for structures of age > 5 years, use of the R-values in the above table willlimit carbonation to less than 5 mm over 60 years life. For younger structures (age < 5 years), the carbonation

may be more than 5 mm over the remaining years.

The above recommended R-values for older construction are only for guidance. For old structures with

sufficient carbonation data from a detailed survey, the Engineer should make reference to the notes on p.30and p.32 in the calculation of the appropriate R-values for application of anti-carbonation coatings.

It is important that the coating achieves the R-value at the minimum expected DFT following application on site. The

target value for DFT (target mean DFT) is calculated from experience as the minimum DFT plus 33%.

The target mean DFT shall be the average DFT achieved by the contractor. If either the minimum DFT measured on siteis less than the specified minimum DFT or the average DFT on site is less than the specified target mean DFT, then athicker coating will need to be applied to meet the specifications.

The dry film thickness (DFT) shall be converted to wet film thickness (WFT), allowing for losses, to get a correct

coverage (L/m). The target mean WFT shall be used by the contractor/supplier to calculate actual coverage rates andnot the minimum DFT or WFT which is commonly done.

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CARBONATIONRESISTANCE

New

Construction

andOlder

Construction

19 (1) The carbon dioxide diffusion resistance of the paint system,measuredinaccordancewithAppendix?2,shallbeexpressedintermsofanR-value.

(2) TherequiredminimumR-valueforthepaintsystemshallbe......m.

(3) TheDFTusedtocalculatetheR-valueforthepaintsystemshallbetheminimumDFTtobeachievedinservice.ThetargetmeanDFTshallbegreaterthantheminimumDFTby33%.

(4) Thepaint shall be appliedin twocoats. shallbenotlessthan150?m.

Theminimum DFT

(5) The SD value of the paint system at the meanDFT shall not

exceed4?m equivalent air layer resistanceandshall bemeasured inaccordancewithAppendix?1.

(6) Theadhesionofthepaintsystem,measuredinaccordancewithAppendix?8,shallbesatisfactory.

(7) Thepaintsystemshallnotsupportalgalgrowth,whenmeasuredinaccordancewithAppendix?12.

(8) WateruptakebythepaintsystemshallbezerowhenmeasuredinaccordancewithAppendix?10.

(9) The requirements of Clauses 19(2) and 19(6) shall also besatisfied after 4000 hours artificial weathering in accordance withAppendix?3.

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Notes

Selection of Anti-carbonation Coatings for Application to Old Construction with Sufficient Carbonation Data from aDetailed Survey

The first step is to estimate the carbonation coefficient of the concrete, by measurement of the carbonation depth

around the structure. This is done by taking the maximum carbonation recorded or a value that more appropriatelyrepresents the carbonation state of the structure (X

o), and substituting into equation (1) to obtain the carbonation

coefficient (D),

X o

D = (1)

2To

where

D = carbonation coefficient (mm/year)

Xo

= actual carbonation depth (mm)T

o= age of the structure (year)

The second step is to select the parameters necessary for estimating the required R value of the coatings as follows :

(a) Maximum depth of carbonation before reinforcing bar becomes active (XM).

(b) Required design life of the structure (TM).

According to Engelfried(1)

, depth of carbonation for older construction with a coating applied at some point after

construction is given by :

X = (Sc + K)

- S

c(2)

where

Sc = carbonation resistance of the coating, expressed as an equivalent thickness of

concreteK = 2S X + X + 2DTc o o E

TE

= elapsed time since application of the coating

Thus, in order to determine the necessary performance of a coating, the appropriate parameters are fed into equation

(2), as follows :

XM

= (Sc + K)

- S

c(3)

and

K = 2S X + X + 2D(T - T )c o o M o

By re-arranging equation (3), Sccan be obtained:

Xo + 2D(TM- To) - XMS

c= (4)

(2XM- 2X

o)

The R-value for the coating can then be calculated as follows,

R = Sc

c(5)

where

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NotesR = equivalent air layer resistance to carbon dioxide diffusion

c

= carbon dioxide diffusion resistance for concrete (typically 400)

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Notes

Example

A 7-year old concrete structure was found to have a carbonation depth ranging from 15 mm to 23 mm. It was proposedto select an anti-carbonation protective coating to reduce further carbonation to less than 5 mm in the next 25 years.

Solution

Design for the worst case, choose:X = 23 mm

o

XM

= 28 mmT

o= 7 years

TM

= 32 years

Using Equation (1),

X o

D =

2To

23=

2 7

= 38 mm2/year.

Hence, substituting into equation (4),

23 + 23825 - 28S =

c

(228 - 223)

= 163 mm

Using equation (5), therefore,

R = 163 400 mm

= 65200 mm

= 65 m (say)

Hence the Engineer should select a coating which has the property of R 365m. Provided that the coating is appliedproperly with sufficient film thickness and that degradation of the coating under natural weathering will not reduce theR value of the coating to below 65 m, then the carbonation front will not advance more than 5 mm in the next 25 years.

If the coating is expected to degrade to R < 65 m within the design life, then recoating will be required. The Engineerwill thus need to consider the need to recoat the structure to ensure a continuous, high performance barrier is present.

REFERENCE :

(1) Engelfried, R., "Carbonation of Unprotected Concrete and its Control by Means of Coatings", Defazet, V31, n9,

1977, pp 353-359.

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NotesClause 20

Situations occur where concrete is saturated on one face, but is exposed to the air or sea spray on others. Structures

which are subject to these conditions include water towers, swimming pools and subways.

Where this occurs, coatings must not form a barrier to the passage of water vapour through the concrete, otherwiseblistering of the coating may occur. The thickest area of the coating will be at greatest risk from blistering, hence the

maximum thickness is specified for testing in accordance with Appendix 1 of this Model Specification.

Coatings which are suitable for application in these conditions include the higher performance acrylics and

cementitious coatings. Coatings which are unlikely to be suitable include barrier coatings based on epoxy andpolyurethane resins.

Clause 21

Paints which would be expected to comply with Clause 21 are moisture curing or two-component polyurethane based

systems, with the property to penetrate into the concrete surface. These types of paint may not necessarily becompatible with all the requirements contained in Clauses 19 & 20.

Clause 22

The coatings applied to structures in the splash zone and atmospheric zone should have good resistance to U.V.,

abrasion, and be suitable for application under high humidity/moisture conditions. The aesthetic considerations arenormally of secondary importance.

Suitable coating systems include acrylic and polyurethane. Epoxy and coal tar epoxy may also be used if protectedfrom sunlight. Coating systems not appropriate for wet applications or not suitable for splash zones are water based

coatings and soft coatings such as bituminous coatings.

Water-repellent systems such as silanes are not suitable for lower grade concrete, as rapid carbonation would occur.However, for new construction of Grade 45 and above or where carbonation is not a concern, the R-value requirementmay be waived, allowing the use of water-repellent systems. The non-film forming water repellent system should be

specified to comply with Clauses 22(2) and 22(3), at the manufacturer's minimum recommended coverage rate. Also,the treated concrete should be resistant to water uptake when measured in accordance with Appendix 10 of this Model

Specification, both before and after artificial weathering to 4000 hours in accordance with Appendix 3 of this ModelSpecification.

Clause 23

The coatings applied to structures in the tidal zone will be subject to abrasion from various floating objects and

possible contamination by oils and solvents.

Coating systems such as cross-linking high performance epoxy, coal tar epoxy and polyurethane are normallyeffective for immersed conditions. Heavily modified cement based coatings may not be suitable for permanent

immersion and are not recommended.

For structural elements subject to flexural cracking under load, the paint system should be specified not to fail under1000 cycles of flexure when tested in accordance with Appendix 6 of this Model Specification at a temperature of 27

2C.

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BackPressure

Actingon

Coatings

20 (1) Therequirements forpaintsapplied tonewconcreteor to oldconcrete shall be in accordance with Clause19, except as stated inClauses?20(2)and20(3).

(2) The SDofthepaintsystemshallnotexceed4?mequivalentairlayerresistanceatthemaximumDFT,measuredinaccordancewithAppendix?1.ThemaximumDFTshallnotbegreaterthan1.5timesthe

targetmeanDFT.

(3) The water permeability measured in accordance withAppendix?7, Clause?7.5(2), shall classify the coating system asresistantattherecommendedthickness.

Concrete

Subjectto

Graffiti

21 InadditiontoanyrequirementscoveredbyClauses19and20,paintswhicharesubjecttograffitimusthavethefollowingproperties:

(a) Thepaintsystem shallbe resistant to treatmentwiththesolventsnecessaryfortheremovalofsolvent-basedspraygraffiti.

(b) The paint system shall be resistant to high pressurewashingusedtoremovepostersandwater-basedgraffiti.

SPECIFIC REQUIREMENTS

RESISTANCE

FOR CHLORIDE

Concrete

SubjecttoChloride

Sprayand

Carbonation

22 (1) The paint system shall comply with Clause 19 or Clause 28

exceptasstatedinClauses?22(2)and22(3).

(2) Thepaint system shallberesistant to theingress of salt spraywhenmeasuredinaccordancewithAppendix?4.

(3) Thepaint systemshallbe resistant to salt spray in accordancewithClause22(2)after4000hoursartificialweatheringtoAppendix?3.

Concrete

Subjectto

Cyclic

Immersion

inSeawater

23 (1) The paint system shall be formulated for application ontosurfacedrybutsaturatedconcreteinthetidalrange.

(2) The paint system shall cure rapidly between the tidal cycles,such that it may be immersed in seawater within 3 hours ofapplication.

(3) Thepaintsystem shallberesistant tothediffusionofchlorideionwhentestedinaccordancewithAppendix?5.

(4) The minimum DFT of the paint system, tested in accordancewithClause1.3(6)atAppendix1,shallbetheminimumDFTforthefield application; thetargetmean DFTshall beatleast 33%greater

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Notes

Clause 24

Water repellent systems such as silanes are not suitable for lower grade concrete, as rapid carbonation would occur.However, for new construction of Grade 45 and above or where carbonation is not a concern, the R-value requirement

may be waived, allowing the use of water repellent systems. The non-film forming water repellent system should be

specified to comply with Clauses 22(2) and 22(3), at the manufacturer's minimum recommended coverage rate. Also,the treated concrete should be resistant to water uptake when measured in accordance with Appendix 10 of this Model

Specification, both before and after artificial weathering to 4000 hours in accordance with Appendix 3 of this ModelSpecification.

Clause 26

Coatings will be immersed and subject to a variety of chemicals, including possible acid attack due to sulphur

oxidizing bacteria.

Coating systems such as cross-linking high performance epoxy, coal tar epoxy and polyurethane normally perform

well under exposure to sewage.

Where the concrete structure is expected to crack, perhaps due to shrinkage or flexural movement, the paint systemshould be specified to be reinforced with glass-fibre fabric, of density 280-300 g/m open weave lapped by 25 mm at its

edges. In such circumstances, the minimum DFT of the system would be expected to exceed 1 mm.

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thantheminimumDFT.

(5) Thepaint shall be appliedin twocoats. shallbenotlessthan150?m.

Theminimum DFT

(6) Thewaterpermeabilityofthecoating,measuredinaccordancewithAppendix?7,Clause?7.5(1),shallbeclassifiedaswaterresistantat

therecommendedthickness.

(7) The adhesion of the coating system, measured in accordancewithAppendix?8,shallbesatisfactory.

(8) The impact resistance of the paint system, measured inaccordancewithAppendix?11,shallbesuchthatnowaterpenetratesthroughthecoatingaftertesting.

Concrete

Water

Retaining

Structures

SubjecttoSalt

Spray

24 (1) ThepaintsystemshallcomplywithClauses20or28,exceptasstatedinClauses?24(2)and24(3).

(2) Thepaintsystemshallbe resistant to theingressofsaltspray,whenmeasuredinaccordancewithAppendix?4.

(3) Thepaint systemshallbe resistant to salt spray in accordancewithClause24(2)after4000hoursartificialweatheringtoAppendix?3.

Concrete

Subjectto

Chloride

Back-penetration

fromSoil

25 (1) ThepaintsystemshallcomplywithClause20or28,exceptasstatedinClauses?25(2)and25(3).

(2) Thepaintsystemshallbe resistant to theingressofsaltspray,whenmeasuredinaccordancewithAppendix?4.

(3) Thepaint systemshallbe resistant to salt spray in accordancewithClause?25(2)after4000hoursartificialweatheringtoAppendix?3.

SPECIFIC REQUIREMENTS

RESISTANCE

FOR CHEMICAL

Resistance

toSewage

26 (1) Thepaint shall be appliedin twocoats. Theminimum DFT

shallbenotlessthan150?m,andthetargetmeanDFTshallbenotlessthan200?m.

(2) ThepaintsystemcomplyingwithClause26(1)shallbetestedinaccordance with Appendix?9, using 1% sulphuric acid test solution,andshallnotdeteriorateovera3monthtestduration.

(3) ThebondstrengthofthepaintsystemmeasuredinaccordancewithAppendix?8,shallbesatisfactory.

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Notes

Clause 27

In this environment, coatings may be immersed in strong acids, alkalis and solvents.

Coating systems such as high performance solvent free epoxy and coal tar epoxy with at least 400 m DFT are likely tobe suitable.

Where the concrete structure is expected to crack, perhaps due to shrinkage or flexural movement, the paint systemshould be specified to be reinforced with glass-fibre fabric, of density 280-300 g/m open weave lapped by 25 mm at its

edges. In such circumstances, the minimum DFT of the system would be expected to exceed 1 mm.

Clause 28

The ability of concrete to crack, opening to widths from hairline to 0.3 mm, places very high stresses on paint films. In

order to bridge cracks successfully the coating must have a substantial thickness, typically with a minimum DFT of at

least 300 m, and be elastomeric or plastomeric in physical terms.

Elastomeric coatings for concrete are typically polyurethane based, whereas plastomeric are soft acrylic copolymerformulations, which commonly have high rates of dirt pick-up and may need cosmetic top coats.

Alternative approaches are either to reinforce over the crack with glass-fibre fabric, or to chase out the crack, fill thechase with sealant and then apply a conventional paint.

It is unlikely that crack-bridging paint systems will perform adequately when applied over existing brittle paint finishes.

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Notes

Clause 30

This Clause relates to applications on concrete in the splash or tidal zone that remains saturated beneath the concrete

surface.

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(4) The target mean DFT shall be at least 33% greater than theminimumDFT.

(5) Thepaint shallbeapplied in twocoats. shallbenotlessthan150?m.

Theminimum DFT

(6) Thewaterpermeabilityofthecoating,measuredinaccordancewithAppendix?7,Clause?7.5(1),shallbeclassifiedaswaterresistantattherecommendedthickness.

(7) The adhesion of the coating system, measured in accordancewithAppendix?8,shallbesatisfactory.

(8) The impact resistance of the paint system, measured inaccordancewithAppendix?11,shallbesuchthatnowaterpenetratesthroughthecoatingaftertesting.

WetConcrete

Surfaces

30 (1) Paintforapplicationin thetidalandsplash zoneshall comply

withClauses29(1)to29(8).(2) Allconcretesurfacestoreceivepaintshallbefreefromsurfacewateratthetimeofapplication.

(3) Forworkingabovewater,temporaryanti-splashprotectionshallbeprovidedtoreducetheeffectofwaveactioninre-wettingconcretesurfaces.

(4) Paintingworksshallbeprogrammedtomeetthemanufacturersminimumtimelimitbeforethepaintcanbeimmersedinwater.

(5) ThepaintshallbeappliedinaccordancewithClauses?16(4)and16(5).

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NotesListed below are short lists of some types of coating system studied by Consultancy Agreement No. 47/88

SHORTLIST OF ANTI-CARBONATION COATINGS

Coating system Supplier Generic TypeRecommendedDFT (microns)

Granoimpact Roma Cali-Empire Ltd Acrylic 440

Granogloss Cali-Empire Ltd Acrylic 200

SBD Stonepaint Dodwell Industrial Acrylic 250

SBD Weatherproof Dodwell Industrial Acrylic 250

Decadex Expandite-Interswiss Acrylic 350

Dekguard/Topcoat W Foseco Industries Silox/Acrylic 300

Dekguard/Topcoat S Foseco Industries Silox/MMA 140

Thorolastic ICI-Thoro Acrylic 325

Emer-Clad New Asia Engg Acrylic 350

Icosit Cosmetic Sika Ltd MMA 120

Elastofil Sika Ltd Acrylic 900

SHORTLIST OF COATINGS TO RESIST SEAWATER SPRAY

Coating system Supplier Generic TypeRecommended

DFT (microns)

Hdrozo Clear 16 Ameron Ltd Silane N/ABerger C.R. Finish Berger Paints Ltd Chlor.Rubber 200

Granoimpact Rolana Cali-Empire Ltd Acrylic 210

SBD Aquapel WR Dodwell Industrial Silane N/A

Hardac Acrylic Sealer Dodwell Industrial Acrylic N/A

FCR 851 Expandite-Interswiss Cement 2000

Nitocote EP 430 Foseco Industries Epoxy 400

EP 41 Loyal Enterprise Epoxy 200

Dekguard/Topcoat S Foseco Industries Silox/MMA 140

Interguard EF/Interthane PQ International Paint Epoxy-P/U 150

Icosit Cosmetic Sika Ltd MMA 120

Only where protected from sunlight

Nitocote ET 550

Nafulan I Dick

Eptar 56

Foseco Industries

Univic Engineering

Loyal Enterprise

Tar Epoxy

Tar Epoxy

Tar Epoxy

350

500

225

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NotesSHORTLIST OF COATINGS TO RESIST SEAWATER IMMERSION

Coating system Supplier Generic Type

Recommended

DFT (microns)

Luxatar 6 Berger Paints Tar Epoxy 800


Nitocote ET 401 Foseco Industries Tar Epoxy 500



Dulux Epoxy Bildcote AR580 ICI Ltd Epoxy 300

Intergard EF/Intertuf JJA 180 International Paint Epoxy-P/U 300

Concresive 1447/1448, Hydrocote Inter Pacific Ltd Epoxy 500

Eptar 56 Loyal Enterprise Ltd Tar Epoxy 225

EP 41 Loyal Enterprise Ltd Epoxy 200

Emer-Tar Epoxy New Asia Engineering Tar Epoxy 200

Irathane Pyrok Industries Polyurethane 225

Coluriet TCN 300 Sigma Coatings Tar Epoxy 300

Poxitar F Sika Ltd Tar Epoxy 150

Probond 811C/EC-400 Spray Engineering Epoxy 500

Rust-Oleum 9578 Topman International Tar Epoxy 200

Escoweld 7502 E Univic Engineering Ltd Epoxy 500

MC-DUR 1500 ToF Univic Engineering Ltd Tar Epoxy 500

Suitable for Contact with Potable Water


SHORTLIST OF CRACK-BRIDGING ANTI-CARBONATION COATINGS

Coating system Supplier Generic TypeRecommended

DFT (microns)

SBD Weatherproof EC Dodwell Industrial Acrylic 800

Decadex Expandite-Interswiss Acrylic 350

Dekguard Elastic Foseco Industries Acrylic 400

Thorolastic ICI-Thoro Acrylic 325

Emer-Clad Reinforced New Asia Engg Acrylic 750


Barracryl Sanxoz Master Builders Acrylic 300

Icosit Elastic Sika Ltd Ethylene 300

Elastofil Sika Ltd Acrylic 900

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NotesSHORTLIST OF COATINGS TO RESIST SEWAGE


Recommended

DFT (microns)

Amercoat 78 HB Ameron Ltd Tar Epoxy 400

Epoxy Plus Coating Dodwell Industrial Epoxy 500

Epilux 4 Berger Paints Tar Epoxy 215





Dulux AR 431-7790/7791 ICI Ltd Tar Epoxy 200

Concresive 1170 Inter Pacific Ltd Epoxy 200

Eptar 56 Loyal Enterprise Ltd Tar Epoxy 225

Emer-Tar Epoxy New Asia Engineering Tar Epoxy 200


Colturiet TCN 300 Sigma Coatings Tar Epoxy 300Poxitar F Sika Ltd Tar Epoxy 285

Poxitar Sika Ltd Tar Epoxy 285

Probond 711C/EC-400 Spray Engineering Epoxy 500

Rust-Oleum 9578 Topman International Tar Epoxy 200

Escoweld 7502 E Univic Engineering Ltd Epoxy 500

MC-DUR 1500 ToF Univic Engineering Ltd Tar Epoxy 500

Suitable for Contact With Potable Water


SHORTLIST OF COATINGS TO RESIST CHEMICALS


Recommended

DFT (microns)

Nitocote EP 403

Nitocote ET 401

Nitocote EP 430

Resicote F7/Resilay HB

Probond EC-400

Escoweld 7502 E

MC-DUR 1500 ToF

Foseco Industries

Foseco Industries

Foseco Industries

Sui Tai Ltd

Spray Engineering

Univic Engineering

Univic Engineering

Epoxy

Tar Epoxy

Epoxy

Epoxy

Epoxy

Epoxy

Tar Epoxy

400

500

400

500

500

500

500

Suitable for Contact With Potable Water


SHORTLIST OF CRACK-BRIDGING COATINGS TO RESIST SEA SPRAY


Recommended

DFT (microns)

SBD Weatherproof EC/Aquapel WR

Irathane

Dodwell Industrial

Pyroc Industries

Siloxane/Acrylic

Polyurethane

800

225

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45APPENDIX1

DETERMINATION OF THE WATER VAPOUR


Scope 1.1 Thismethodcoversthedeterminationofthewatervapourdiffusion

resistance of coatings for concrete by measuring the water vapourtransmissionthroughacoatedcomposite.

Test 1.2 Unglazedceramictilesof100x100x5mmsizeshallbeusedastheSubstrate substrate.Thetilesshallbeofuniformqualityandfromasinglebatch,

freefromcontamination.

Procedure: 1.3 (1) The tilesandallmaterialsshallbeconditionedfor24hoursatPreparation theapplicationconditionsof27 Cand80 5 %rel ati ve hu mi dit y of

Specimens (2) The coating system shall be applied in accordance with themanufacturers instructions, using all necessary primers andundercoats,andcoverageratesshallbecheckedbyweighing.

(3) Applicationshallbebyspray,brushorroller.

(4) 10 tiles shall be prepared in oneoperation for all tests to becarriedout.

(5) Aftercoating,the specimensshall beconditionedat27 Cand80 5 %rel ati ve hu mi dit yf or 6 weekst o per mit nat ural l oss o

solventsandothervolatilematerials.(6) Following conditioning, 2 tiles shall be sawn in half and themaximum, minimum and mean DFT measured using a travellingmicroscope; the mean value shall be taken from at least 30observations.

(7) 2tilesshallbelabelledandstoredinalight-fastboxtoserveascolourcontrolpanelsforartificialornaturalweatheringtests.

Procedure: 1.4 (1) Thesample shallbe set in ametal cell using silicone rubber,

Determination suchthattheuncoatedfaceshallbesealedaboveareservoirofdistilled ofWater water. Vapour

Transmission (2) Theunit shallbeplaced inadesiccator at 27 Cand 0% Rate relativehumidity.Thechangeinweightoftheunitwithtimeshallbe

measuredperiodically.

(3) Themeasurementshallbecontinueduntilasteady-stateweightlosshasbeenrecordedforacontinuous3dayperiod.

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46Calculation 1.5 (1) Thewatervapourtransmission ratefor thecoatedtile shall be

calculatedinaccordancewiththeequation:

dGWVT = (g/m2per24hr)

T.Awhere:

WVTisthewatervapourtransmissionrate(g/m2per24hr),

dGistheweightchangeundersteady-stateconditions(g),

Aisthetestarea(m2),and

TisthetimeduringwhichdGoccurred(24hrunits)

(2) Thewatervapourdiffusioncoefficientshallbecalculatedforthecomposite,fromwhichthediffusioncoefficientforameasuredmeanthicknessofcoating shall beobtained. The water vapour diffusioncoefficientforthecompositeshallbecalculatedfromtheequation:

WVT.tTdT = (cm2/s)

H2O

Pwwhere:

dT isthewatervapourdiffusioncoefficient(cm2/s),H2O

WVTisthewatervapourtransmissionrate(g/m2per24hr),

tTisthethicknessofthecomposite(cm),and

Pw is the density of saturated water vapour at the testtemperature(g/cm3)

(3) Theperformanceofthecompositeisthengivenby:

tT tt tc= +

dT dt dc H2O H2O H2O

where:

tTisthethicknessofthecomposite(cm),

ttisthethicknessofthetile(cm),

tcisthethicknessofthecoating(cm),

dT is the water vapour diffusion coefficient for theH2O

composite(cm2/s),

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47 dt isthewatervapourdiffusioncoefficientforthe tile

H2O

(cm2/s),and

dc isthewatervapourdiffusioncoefficientforthecoatingH2O

(cm2/s)

(4) Theequivalentairlayerresistanceofthecoatingtothediffusion

ofwatervapourshallbecalculatedfromtheequation:

daH2O

SD = tc (m)dc

H2O

where:

SDistheequivalentairlayerresistance(m),

da isthediffusioncoefficientforwatervapourinair,whichH2Oisequalto0.242cm2/s)

tcisthethicknessofthecoating(m),and

dc isthewatervapourdiffusioncoefficientforthecoatingH2O

cm2/s

(5) The water vapour diffusion resistance of the coating shall becalculatedasthemeanoftwodeterminations.

Reportingof 1.6 Thefollowingshallbereported:Results

(a) Thenameofthecoatingsystemandthebatchnumbers.

(b) Thenameofthe manufacturerandHongKongsupplier.

(c) The coverage rates used for each component of thecoatingsystem.

(d) Themeasuredmean,minimumandmaximumDFT.

(e) Commentsonanyapplicationortestingirregularities.

(f) TheresultsforwatervapourdiffusionresistancevalueSDatthemeanDFT.

(g) Whether the samples have been subjected to artificialweatheringandtheduration.

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Figure1.1-Set-upforWaterVa ourDiffusionTest

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APPENDIX2

DETERMINATION OF THE CARBON DIOXIDE


Scope 2.1 Thismethodcoversthedeterminationofthecarbondioxidediffusion

resistance of coatings for concrete by measuring the flow rate of amixtureofoxygenandcarbondioxidegasthroughacoatedcomposite.

Test 2.2 Unglazed ceramic tiles of 100?mmx 100?mmx 5?mmsize shall besubstrate used as the substrate. The tiles shall be of uniform quality and

preferablyfromasinglebatch,freefromcontamination.

Equipment 2.3 Thefollowingequipmentisrequired,asshowninFigure2.1.

(a) Atest chamber to receive5?mm thickunglazedceramictileswithcoatingsystemsapplied.

(b) Supplies of analytical grade 85/15 oxygen and carbondioxidegasblendandheliumgas.

(c) Pressurebalanceequipment.

(d) Agaschromatographandintegrator.

Procedure: 2.4 (1) The tilesandallmaterialsshallbeconditionedfor24hoursatpreparation theapplicationconditionsof27 Cand80 5 %rel ati ve hu mi dit y

ofspecimens (2) The coating system shall be applied in accordance with themanufacturers instructions, using all necessary primers andundercoats,andcoverageratesshallbecheckedbyweighing.


(4) 10 tiles shall be prepared in oneoperation for all tests to becarriedout.

(5) Aftercoating,the specimensshall beconditionedat27 C

and80 5 %rel ati ve hu mi dit yf or 6 weekst o per mit nat ural l oss o solventsandothervolatilematerials.

(6) Following conditioning, 2 tiles shall be sawn in half and themaximum, minimum and mean DFT measured using a travellingmicroscope; the mean value shall be taken from at least 30observations.

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(7) 2tilesshallbelabelledandstoredinalight-fastboxtoserveascolourcontrolpanelsforartificialornaturalweatheringtests.

Procedure:

determination

ofgasflow

rate

2.5 (1) Afterconditioning,thecoatedsampleshallbecarefullyplacedinthetestchamber.

(2) The gas cylinders shall be turned on and the gas flow ratesmonitoredtoobtainthesameflowrateandpressureonbothsidesofthecoatedtile.

(3) Thesystemshallbeallowedtoequilibrateforatleast24hours.

(4) Thecarbondioxideandoxygendiffusionratethroughthecoatedtilecompositeshallthenbemeasuredbygaschromatography.

Calculation 2.6 (1) ThefluxrateforcarbondioxideshallbecalculatedasthecarbondioxidediffusioncoefficientforthecompositeusingFicksfirstlawofdiffusion:

d=QxL

AxC(cm2/s)

where:

disthecarbondioxidediffusioncoefficient(cm2/s),

Qistheflowrate(mol/s),

Listhethicknessofthecomposite(cm),

Aisthetestarea(cm2),and

Cistheconcentrationdrop(mol/cm3).

(2) Theperformanceofthecompositeisthengivenby:

tT

dTCO2

=tt

dtCO2

+tc

dcCO2

where:

tTisthethicknessofthecomposite(cm),

ttisthethicknessofthetile(cm),

tcisthethicknessofthecoating(cm),

dT isthecarbondioxidediffusioncoefficientfortheCO2

composite(cm2/s),

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dt isthecarbondioxidediffusioncoefficientforthetileCO2

(cm2/s),and

dc isthecarbondioxidediffusioncoefficientforthecoatingCO2

(cm2/s)

(3) Therelativecarbondioxidediffusioncoefficientforthecoating

shallbeexpressedasadimensionlessratio,asfollows:

daCO2

=dc

CO2

where:

istherelativecarbondioxidediffusioncoefficientofthecoating,

da isthecoefficientforcarbondioxidediffusedthroughair,CO2

whichisequalto0.160cm2/s,and

dc isthecoefficientforcarbondioxidediffusedthroughtheCO2

coating(cm2/s).

(4) The resistance of the coating, expressed as an equivalent airlayerthickness,or"R-value",shallbecalculatedasfollows:

R =.t (m)

where:

Ristheequivalentairlayerthickness(R-value)(m),

istherelativecarbondioxidediffusioncoefficientofthecoating,and

tisthemeanDFTofthecoatingundertest(m)

(5) Alternatively,theresistanceofthecoatingmaybeexpressedasanequivalentthicknessofconcretecover,or"S c-value",whichshallbecalculatedasfollows:

R Sc = (m)

c

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where:

Scistheequivalentthicknessofconcretecover,

Ristheequivalentairlayerthickness,and

cisthediffusionresistancefactorforconcrete,typically400.

(6) The carbon dioxide diffusion resistance parameters for thecoatingshallbecalculatedasthemeanoftwodeterminations.

Reportingof

results

2.7 Thefollowingshallbereported:


(b) ThenameofthemanufacturerandHongKongsupplier.




(f) The results for carbon dioxide diffusion resistance intermsof,RandSc,atthemeanDFT.

(g) Whether the samples have been subjected to artificial

weatheringandtheduration.

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Figure2.1-Set-upforGasFluxMeasurement

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APPENDIX3

DETERMINATION OF THE WEATHERING


Scope 3.1 Thismethodcoversthedeterminationoftheweatheringresistanceofcoatings for concrete, applied to various substrates, using a QUVartificialweatheringcabinet.

Test 3.2 Thesubstrateshallbeoneofthefollowing:substrate

(a) Coatedunglazedceramictilesof100x100x5?mmsize.

(b) Coated100mmcoresamples.

(c) Coatedmortarprismsof40?x40x160?mmdimension.

Equipment 3.3 Thefollowingequipmentisrequired:

(a) QUV artificial weathering cabinet fitted with UV-Afluorescenttubes.

(b) Framestoholdconcretecoreandmortarprismspecimensinthespecimentray.

Method 3.4 (1) Coated specimensshallbelocated in thespecimentray of theQUVweatherometer.

(2) Thespecimensshallbetestedinaccordancewiththefollowingweatheringcycle:

6hoursUV-Alightat60+_2C6hourscondensationat50+_2C

for4000hours.

(3) Oncompletionoftheweatheringcycle,avisualinspectionshallbe made to assess the physical defects of the coating system inaccordancewiththestandardmethodsoutlinedin:

-ASTM?D?659-86forchalking,-ASTM?D?660-87forchecking,-ASTM?D?661-86forcracking,-ASTM?D?714-87forblistering,-ASTM?D?772-86forflaking,and-ASTM?D?2616-67(1979)forcolourchange.

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(4) The specimensshallbeconditionedat27+_2Cand80+_5%relativehumidityfor2weekspriortofurthertesting.

Reportingof

results







(f) Visualdefectsrecordedusingstandardtechniques.

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APPENDIX4

DETERMINATION OF THE SALT SPRAY


Scope 4.1 Thismethodcoversthedeterminationofthesaltsprayresistanceofcoatingsforconcretebyusingasaltspraycabinet.

Materials 4.2 Thefollowingmaterialsarerequired.

(a) OrdinaryPortlandcementcomplyingwithBS?12:1989.

(b) Oven-dry natural sand with rounded particle shape andZoneMgradingcomplyingwithBS?882:1983,Table?5.

(c) 20?mm graded coarse aggregate complying withBS?882:1983,Table?4.

(d) Petroleum jelly, mineral oil or a proprietary mouldreleasingagent.

(e) Epoxyresin(AralditeconcreteprimerCMxh125AB)orequivalent.

(f) Artificial seawater, made up with 30 5?g/L sodiuchloride salt in distilled water, complying with thepreparationmethodoutlinedinBS?3900:1985,Part?F12.

Procedure: 4.3 (1) ConcreteofGrade20/20shallbeusedtopreparethespecimens.preparation TheapproximatemixproportionsshallbeinaccordancewithTableof 4.1andtrialmixesshallbeusedtofinalizetheconcretemix.specimens

Table4.1 Mixproportionsforconcretespecimens

OrdinaryPortlandCement(BS?12) 250kg/m3

ZoneMSand(BS?882) 625kg/m320mmGradedAggregate(BS?882) 1250kg/m3

Water(free) 190L/m3

Slump 75mm28daycubestrength(TargetMean) 25MPa

(2) Concrete panels of 500?mm?x 500?mm x 50?mm shall befabricatedusingfair-facedplymoulds.

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(3) Allmaterialsandmouldsshallbeconditionedat27 Cfor24hoursbeforecasting.

(4) Aftermixing,theconcreteshallbeplacedandcompactedwithin30minutesintocleaned,lightlyoiledmoulds.Theconcreteshallbefinished by trowelling with a wood float, and then covered withpolythenesheetingfor24hours.

(5) After24hours,themouldshallbestrippedandthepanelsshallbewrappedinpolythenesheetingandstoredat27 Cforatleast28days,untilreadyforcoatingapplication.

(6) The test faceshall bethemoulded500?mmx500?mmsideofthepanel.

(7) The test face shall be prepared in accordance with themanufacturers instructions by either wire brushing, grit blasting orhighpressurewaterblasting,followedbyfillingofblowholedefectsasrequired.Intheabsenceofinstructionsfromthemanufacturer,amixcomprising1:2.5OPC/ZoneFsandcomplyingwithBS?882:1983and2:1water/SBRsolutionshallbeusedforfillingblowholesanddefects,and shall beapplied to a dampconcrete surface.The filledsurfaceshallbecoveredwithpolythenesheetingandleftfor24hoursat27 Cpriortocoating.

(8) The coating shall be applied in accordance with themanufacturers instructions, using all necessary primers andundercoats,andcoverageratesshallbecheckedbyweighing.


(10) 10panelsshallbeprepared inoneoperationforalltests tobecarriedout.

(11) Aftercoating, thespecimensshall be conditionedat 27 Cand80 5 %rel ati ve hu mi dit yf or 6 weekst o per mit nat ural l oss o solventsandothervolatilematerials.

(12) Followingconditioning,ten100?mmdiameterand50?mmthick

coresamplesshallbetakenfromthepanels.

(13) 2coatedcore samples shall be cut in half and themaximum,minimumandmeanDFTmeasuredusingatravellingmicroscope;themeanvalueshallbetakenfromatleast30observations.

(14) Theconcretesurfacesofthecoreshallbeencasedonallsideswitha5?mmlayerofepoxyresin,exceptforthecoatedface.

(15) After the epoxy resin has hardened and fully cured, thespecimensshallbeplacedinasaltspraycabinetreadyfortesting.

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Procedure:

determination

ofsaltspray

resistance

4.4 (1) The specimen shall be mounted in the salt spray cabinet andshallbetestedinaccordancewiththefollowingweatheringcycle:

4hourssaltwatersprayat40C,8hoursdryingat40Cand30%relativehumidity

for1000hours.

(2) Oncompletionoftheweatheringcycle,thecoatedsurfaceshallbewashedwithdistilledwater.

(3) Thedepthofpenetrationofchloridethroughthecoatingshallbedeterminedindepthincrementrangesof0to5?mm,5?mmto10?mm,and10?mmto15?mmbeneaththecoating,usingthecentral50?mmofthe specimen, by grinding and analyzing the concrete dust inaccordancewithCS1,Vol.2,Clause21.10.2.

(4) Thechloridecontentresultforthecoatingshallbecalculatedasthemeanoftwodeterminations.

Reportingof

results







(f) The results of thechloride contentdetermination, givenbyweightofsampleforeachdepthincrementtestedforbothcoatedanduncoatedconcrete.

(g) The results for the salt spray resistance of the coating,expressingthecoatingasresistantatthemeanDFT,ifthe

chloride content in the 5-10?mm increment range anddeeperis0.04%,ornotresistantatthemeanDFT,ifthechloride content is >0.04%, both before and afterweathering.

(h) Whether the samples have been subjected to artificialweatheringandtheduration.

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APPENDIX5

DETERMINATION OF THE SALT WATER

IMMERSIONRESISTANCEOFCOATINGS

Scope 5.1 This method covers the determination of the salt water immersionresistanceofcoatingsforconcretebyimmersinginartificialseawater.







(f) Artificial seawater made up with 30 5g/litr sodiumchloride salt in distilled water, complying with thepreparationmethodoutlinedinBS?3900:1985,Part?F12.

Procedure: 5.3 (1) ConcreteofGrade20/20shallbeusedtopreparethespecimens.preparationof TheapproximatemixproportionsshallbeinaccordancewithTablespecimens 1.5.1andtrialmixesshallbeusedtofinalizetheconcretemix.

Table1.5.1 Mixproportionsforconcretespecimens


ZoneMSand(BS?882) 625kg/m3

20mmGradedAggregate(BS?882) 1250kg/m3Water(free) 190L/m3


(2) Concrete panels of 500?mm x 500?mm x 50?mm shall befabricatedusingfair-facedplymoulds.

(3)Allmaterialsandmouldsshallbeconditionedat27 Cfor24hoursbeforecasting.

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(4) Aftermixing,theconcreteshallbeplacedandcompactedwithin30minutesintocleaned,lightlyoiledmoulds.Theconcreteshallbefinished by trowelling with a wood float, and then covered withpolythenesheetingfor24hours.



(7) The test face shall be prepared in accordance with themanufacturers instructions by either wire brushing, grit blasting orhighpressurewaterblasting,followedbyfillingofblowholedefectsasrequired.Intheabsenceofinstructionsfromthemanufacturer,amixcomprising1:2.5OPC/ZoneFsandcomplyingwithBS?882:1983and2:1water/SBRsolutionshallbeusedforfillingblowholesanddefects,andshallbeappliedtoadampconcretesurface.Thefilledsurfaceshallbecoveredwithpolythenesheetingandleftfor24hoursat27 Cpriortocoating.

(8) The coating shall be applied in accordance with themanufacturersinstructions,usingallnecessaryprimersandundercoats,andcoverageratesshallbecheckedbyweighing.


(10) 10panelsshallbepreparedinoneoperationforalltests tobecarriedout.


(12) Followingconditioning,ten100?mmdiameterand50?mmthickcoresamplesshallbetakenfromthepanels.

(13) 2coatedcore samplesshall be cut in half and themaximum,

minimumandmeanDFTmeasuredusingatravellingmicroscope;themeanvalueshallbetakenfromatleast30observations.

(14) Theconcretesurfacesofthecoreshall beencasedonall sideswitha5?mmlayerofepoxyresin,exceptforthecoatedface.

(15) After the epoxy resin has hardened and fully cured, thespecimens shall be placed in a container above a tank of artificialseawater,readyfortesting.

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Procedure:

determination

ofsaltwater

immersion

resistance

5.4 (1) Thespecimensshallbeimmersedinartificialseawaterandshallbetestedinaccordancewiththefollowingweatheringcycle?:

6hoursimmersioninartificialseawaterat1metredepthat27i2C,

6hoursdryingat40Cand30%relativehumidity

for1000hours.

(2) Oncompletionoftheweatheringcycle,thecoatedsurfaceshallbewashedwithdistilledwater.

(3) Thedepthofpenetrationofchloridethroughthecoatingshallbedeterminedindepthincrementrangesof0to5?mm,5?mmto10?mm,and10?mmto15?mmbeneaththecoating,usingthecentral50?mmofthe specimen only, by grinding and analyzing the concrete dust inaccordancewithCS1,Vol.2,Clause21.10.2.

(4) Thechloridecontentresultforthecoatingshallbecalculatedasthemeanoftwodeterminations.

Reportingof

results







(f) The results of thechloride contentdetermination, givenbyweightofsampleforeachdepthincrementtestedforbothcoatedanduncoatedconcrete.

(g) Theresultsforthesaltwaterimmersionresistanceofthecoating, expressing the coating as resistant at the meanDFT, if the chloride content in the 5-10?mm incrementrangeanddeeperis0.04%,ornotresistantatthemeanDFT,ifthechloridecontentis>0.04%,bothbeforeandafterweathering.


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APPENDIX6

DETERMINATION OF THE DYNAMIC CRACK

BRIDGINGRESISTANCEOFCOATINGS

Scope 6.1 Thismethodcovers thedeterminationofthedynamiccrackbridgingresistance of coatings for concrete based on German BAMZVT-BEL-OSrecommendations.




(c) Petroleum jelly, mineral oil or a proprietary mouldreleasingagent.

(d) 8?mm single wireprestressing strand,cut to a length of320?mm.

(e) PVCsleeveorrubbertubingof2?mmwallthicknessand8?mminternaldiameter,cutto100?mmlength.

Equipment 6.3 Thefollowingequipmentisrequired.

(a) Apneumatic,leveractioncrackbridgingresistancetestertoBAMZVT-BEL-OS.

(b) Atestcabinetwithtemperaturecontrol to27 C,5M2Cand relativehumiditycontrol to 80 5 %and705%.

(c) Steel prismmouldsof 40?mmx40?mm x160?mmwithPVCinsertsandslotsforprestressingstrandasshownin

Figure6.1.

Procedure: 6.4 (1) Sand-cementmortarshallbeusedtopreparethespecimens inpreparation theproportionsstatedinTable6.1;trialmixesshallbeusedtofinalizeof themortarmix.specimens

(2) ThePVCsleeve shall be fitted onto the central region of theprestressingstrand.

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Table6.1 Mixproportionsformortarspecimens



Water(free) 150L/m3

28daycubestrength(TargetMean) 35MPa

(3) A 3?mm x 16?mm x 40?mm PVC insert and the prestressingstrandshallbeplacedintothelightlyoiledsteelmouldinthepositionshowninFigure6.1.

(4) Themixed sand-cementmortar shallbe carefullyworked intothe mould by tamping with small plastic or steel tamping rod toeliminateallvoids.

(5) Thesurfaceshallbestruckoffandfinishedwithawoodfloat.

(6) Allthespecimensshallbecuredunderpolythenesheetingat27 C.

(7) After3dayscuring,themouldshallbestrippedandtheprismshallbewrappedinpolythenesheetingandstoredat27 Cfor28days.

(8) The floated surface of the prism shall be the test surface toreceivethecoating,asshowninFigure6.2.

(9) The coating shall be applied in accordance withmanufacturer's instructions, using all necessary primersundercoats,andcoverageratesshallbecheckedbyweighing.

theand


(11) 10prismsshallbepreparedinoneoperationforallteststobecarriedout,includingspares.

(12) Aftercoating,theprismspecimensshallbeconditionedat27b2Cand80 5 %rel ati vehumi dit y f or 6 weekstoper mit nat ural l os

ofsolventsandothervolatilematerials.Procedure:

determination

ofcrack-

bridging

resistance

6.5 (1) The coated test specimen shall be fixed into the testingequipment.

(2) Thespecimenshallbe settoproducean initialcrackwidthof0.05?mm(Wu)withamanualorelectronicmovementgaugesfixedtothesideofthespecimenoverthecrack.

(3) Themaximumcrackwidth forthe test shallbeset to 0.3?mm(Wo).

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(4) Thefrequencyofthetestfortheopeningofthecrackshallbesetto1?Hz.

(5) Theequipmentandthecoatedtestspecimenshallbemaintainedinthetestcabinetat27 Cand80 5 %rel ati vehumi dit y

(6) Thetestshall be startedbycyclingthe test specimen with the

crack opening between WuandWo in a sine wave form for 1000cycles.

(7) After1000cycles,thecoatedsurfaceshallbeexaminedwithamagnifyingglasstocheckforcracks.

(8) The test shall be repeated with a new specimen of the samecoatingsystembutshallbetestedinthetestcabinetat5 Cand70 5 %rel ati vehumi dit y

(9) Oncompletionoftesting,thespecimenshallbecutinhalfandtheDFTmeasuredusingatravellingmicroscope;themeanvalueshallbetakenfromatleast15observations.

(10) Two test specimens shall be used to determine thecrack-bridging capacity of the coating system at each temperature.Neither specimen shall fail after 1000cycles. The coating shall beclassified as suitable foruseover dynamic cracks provided that thefilmhasnotfailedattheendofthetest.

Reportingof

results







(f) The results for crack-bridging resistancetemperatureatwhichtestingwasundertaken.

and the


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Figure6.1- MouldforCrack-bridgingTestSpecimen

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Figure6.2- SectionthroughCrack-BridgingTestSpecimen

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APPENDIX7

DETERMINATIONOFTHEWATER

PERMEABILITYRESISTANCEOFCOATINGS

Scope 7.1 This method covers the determination of the water permeabilityresistanceof coatings forconcreteby laboratorybased andportablein-situpermeabilitycells.







Equipment 7.3(1) The laboratory based permeability cell may be of variousdesigns,andshallcomprisethefollowing:

(a) Astainlesssteeltopring.

(b) Astainlesssteelbottomplatewithaholedrilledtoformthewaterinlet.

(c) Aperspexwindowtofitintothecentreofthetopring.

(d) Ataperedbrasssleeve,beingwidestattheupstreamend,

withO-ringsealsateachend.

(e) AtaperedbrasssleevewiththesamedimensionasthatinClause?7.3(d),exceptwithoutO-ringseals.

(f) Astainlesssteelbarasaclampfortheperspexwindow.

(g) Stainlesssteelboltstoholdthetopringandbottomplatetogether.

(h) Stainlesssteelconnectingtubing.

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(i) Equipmenttoproducepressurizedwater(seeClause7.5(1)(b).

(2) The portable permeability cell shall be the CLAM in-situpermeabilitytesterdevelopedbyQueensUniversity,Belfast.

Procedure:

preparationof

7.4 (1) ConcreteofGrade20/20shallbeusedtopreparethespecimens

andtheapproximateproportionsshallbeinaccordancewithTable?7.1;trialmixesshallbeusedtofinalizetheconcretemix.

specimens




20mmGradedAggregate(BS?882) 1250kg/m3

Water(free) 190L/m3



(3) Allmaterialsandmouldsshallbeconditionedat27 Cfor24hoursbeforecasting.

(4) Aftermixing,theconcreteshallbeplacedandcompactedwithin30minutesintocleaned,lightlyoiledmoulds.Theconcreteshallbefinished by trowelling with a wood float, and then covered with

polythenesheetingfor24hours.

(5) After 24 hours, the mould shall be stripped and the panelswrappedinpolythenesheetingandstoredat27 Cforatleast28days,untilreadyforcoatingapplication.


(7) The test face shall be prepared in accordance with themanufacturers instructions by either wire brushing, grit blasting or

highpressurewaterblasting,followedbyfillingofblowholedefectsasrequired.Intheabsenceofinstructionsfromthemanufacturer,amixcomprising1:2.5OPC/ZoneFsandcomplyingwithBS?882:1983and2:1water/SBRsolutionshallbeusedforfillingblowholesanddefects,and shall beapplied to a dampconcrete surface.The filledsurfaceshallbecoveredwithpolythenesheetingandleftfor24hoursat27 Cpriortocoating.


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(10) 10panelsshallbepreparedinoneoperationforalltests tobecarriedout,includingspares.

(11) Aftercoating, thespecimensshall be conditionedat 27 Cand80 5 %rel ati vehumidityfor 6 weekstoper mit nat ural l oss o solventsandothervolatilematerials.

(12) Followingconditioning, ten100?mmdiameterby50?mmthickcoresamplesshallbetakenfromthepanels.

(13) 2coatedcore samplesshall be cut in halfand themaximum,minimumandmeanDFTmeasuredusingatravellingmicroscope;themeanvalueshallbetakenfromatleast30observations.

(14) Thetopcoatedsurfaceand thebottomconcretesurfaceof thecoreshallbemaskedwithdraftingtapeandthespecimenplacedinalightlygreasedtaperedbrasssleevewithoutO-ringseals.

(15) Thevoidbetweentheconcreteandthesleeveshallbefilledwithepoxyresin.

(16) After the epoxy resin has hardened and fully cured, thespecimensshallberemovedfromthesleeveandthedraftingtapeshallberemovedfrombothsurfaces.

Procedure:determination

ofwater

permeability

bylaboratory

testrig

7.5 (1) The short term water permeability resistance of the coatingsystemshallbedeterminedasfollows:

(a) Thespecimenshallbeplacedinthepermeabilityrigwithalltheboltstightened.

(b) Thewater,at2barpressure(20?mhead),shallbeappliedthrough the rig to the bottom (uncoated) face of thespecimen.

(c) Thetimeforwatertoappearthroughthecoatedfaceshall

berecordedovera24hourperiod.

(d) Thewaterpermeabilityofthecoating,measuredfromtwodeterminations shall be considered resistant if no waterhaspenetratedthroughthecoatingduringthetestperiod.

(2) The long term water permeability resistance of the coatingsystemshallbedeterminedinaccordancewithClause?7.5(1),exceptthatthedurationofthetestshallbethreemonths.

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Procedure: 7.6 The procedure from the operation manual of the CLAM In-situdetermination PermeabilityTestershallbefollowed.ofwater

permeability

byCLAM

Tester

Reportingof 7.7 Thefollowingshallbereported:results

(a) Thenameofthecoatingsystemandbatchnumbers.





(f) Theresultsforshort termresistancetowaterpenetrationatthemeanDFT.

(g) TheresultsforlongtermresistancetowaterpenetrationatthemeanDFT.


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Figure7.1- PermeabilityTestRig

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APPENDIX8

DETERMINATION OF THE BOND STRENGTH

OFCOATINGS

Scope 8.1 Thismethodcoversthedeterminationofthebondstrengthofcoatingsforconcretebythedirectpull-offtest.






(e) Asteeldollyof50mmdiametertofitforthedirectpull-offtester.

(f) Fastsetepoxyadhesive.

Equipment 8.3 TheLIMPETtesterdevelopedbyQueensUniversity,Belfast,shallbeused.

Procedure: 8.4 (1) ConcreteofGrade20/20shallbeusedtopreparethespecimenspreparationof andtheapproximateproportionsshallbeinaccordancewithTable?8.1;specimen trialmixesshallbeusedtofinalizetheconcretemix.



ZoneMSand(BS?882) 625kg/m320mmGradedAggregate(BS?882) 1250kg/m3

Water(free) 190L/m3



(3) Allmaterialsandmouldsshallbeconditionedat27 Cfor24

hoursbeforecasting.

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Procedure:

determination

ofbond

strength

(4) Aftermixing,theconcreteshallbeplacedandcompactedwithin30minutesintocleaned,lightlyoiledmoulds. Theconcreteshallbefinished by trowelling with a wood float, and then covered withpolythenesheetingfor24hours.


(6) Thetestfaceshallbe themoulded500x500?mm side of thepanel.

(7) The test face shall be prepared in accordance with themanufacturersinstructionbyeitherwirebrushing,gritblastingorhighpressurewater blasting, followedby filling of blow hole defects asrequired. Intheabsenceof instructionsfromthemanufacturer,amixcomprising1:2.5OPC/ZoneFsandcomplyingwithBS?882:1983and2:1water/SBRsolutionshallbeusedforfillingblowholesanddefects,and shall be applied to a damp concrete surface.The filled surfaceshallbecoveredwithpolythenesheetingandleftfor24hoursat27t2Cpriortocoating.



(10) 10panelsshallbepreparedinoneoperationforalltests tobecarriedout,includingspares.


(12) Followingconditioning,a50?mmdiameterpartialcoreshallbemade at 3 test locations to a nominal depth which shall be 5?mmgreaterthanthethicknessofthecoatingundertestsoastoensurethatthe50?mmcorebitpassesintotheconcretesubstrate.

(13) 2coatedcore samples shallbe cut in half and themaximum,minimumandmeanDFTmeasuredusingatravellingmicroscope;themeanvalueshallbetakenfromatleast30observations.

8.5 (1) Thecoatedsurfaceofeachpartialcoreshallbedegreasedwithalcoholandasteeldollyshallbebondedontothecoatingusingfastsetepoxyadhesive.

(2) Aftertheepoxyhascuredandhardened,theLimpettestershall besetoverthedollyandthepullrodshallbescrewedintothethread

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ofthedolly.

(3) Thetestprocedureoutlinedintheoperationmanualofthetestershallbefollowed.

(4) Afterfailure,thefailureloadshallberecorded.

(5) Themodeoffailureshallberecordedbyexaminingtheportionadhering to the dolly as shown in Figure 8.1 and using the systemlistedinTable8.2.

Table8.2:Failuremodeofbondstrengthtest

Category FailureMode

Type1 Concretebond-concreteandcoatingattachedtodolly

Type2 Primerbond-topcoatsandprimerattachedtodolly

Type3 Intercoatbond-failurebetween:

(a) primerandtopcoat(b) topcoatsorwithincoating(c) topcoatanddollyadhesive

Note: wherecombinedfailuresoccur,thepercentagesof each typeoffailureshallbegiven(e.g.30%Type1,70%Type?3b).

(6) The adhesion of the coating system sh

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