SlipCoefficientandTensionCreepTestingofCoatingsUsedinSlipCriticalBoltedConnections

WilliamD.Corbett.ProfessionalServicesBusinessUnitManagerCarlyM.McGee,PhysicalTestingLaboratorySupervisor

KTATator,Inc.Abstract:AppendixAoftheAISCSpecificationforStructuralJointsUsingHighStrengthBoltspublishedbytheResearchCouncilonStructuralConnectionsdescribesthetestingmethodstodeterminetheslipcoefficientofcoatingsused inboltedconnections.Thispaperdescribesthe importanceofestablishingtheslipcoefficientof fayingsurfaces,andpresentsthesouptonutsprocessassociatedwithtestingand certifying coatings used in slipcritical connections from test panel fabrication to surfacepreparation,coatingapplication(includingthinning,thicknessandcuringvariables),selectionofmatingsurfaces, testing for resistance to slip and tension creep, and data reporting, including A, B and Cclassifications.Data from various generic coating types previously tested is presented, and researchneedsaredescribed.Finally,theimportanceofapplicationandcuringofthecoatingintheshoporfieldaccordingtothevariablesemployedduringtestingandcertificationisreinforced.Thispaperwillenablethereaderto:1.Listthevariablesaffectingslipcoefficientvalues2.Describetheprocessassociatedwithtestpanelpreparationandcoating3.Identifythetestingproceduresforslipcoefficientandtensioncreep4.Describetheimportanceofverifyingconformancetotestingvariablesduringshop/fieldapplicationBackground Buildings,bridgesandother structures commonlyemploybolted connectionsof steelbeams,girders and other structural members using gusset plates of various sizes and configurations. Highstrengthbolts (e.g.,ASTMA325orASTMA490)areused to secure theconnections.Theholes in thesteelmembersandthegussetplatesarelargerthantheboltshaft(typically1/161/8larger)toenablethebolttobeinsertedandtensionedagainstthewasherandnut.Theinterfaceofthegussetplateandthestructuralmemberiscalledafayingsurface.Fayingsurfacesarenotrequiredtobecoated,butareoftenprotectedtopreventcorrosionfromoccurringattheinterfaceandrustbleedfromstainingcoatedsurfacesadjacent to the connection.Whenadesignerelects to coat the faying surfaces, the coatingusedonthesesurfacesmustpossessslipresistantpropertiestoreducefatigueontheconnectionduringloading/unloadingcycles(i.e.vehiclestravelingacrossabridgedeck).Sopriortouse,thecoatingsusedonthesefayingsurfacesmustbetestedandclassifiedforslipcoefficientproperties.Oncetheclassifiedcoating isapplied, theconnectionpointsaremasked topreventsubsequentcoats from inadvertentlycontactingtheseareas.

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Thereisnostipulationforspecificcoatingtypesthatmustbeusedintheseboltedconnections,although zincrichprimersarecommonand typicallypossess slip resistanceproperties.Othergenericcoating typeshavebeen testedandused, includingpolyamideepoxyprimers.Otherproductssuchasthermalspraycoatings(variousalloys)androughenedhotdipgalvanizedsteelmaybeviablecandidates,providedtheyhavebeentestedanddemonstrateslipresistantproperties.SpecificationforStructuralJoints TheAmericanInstituteofSteelConstruction,Inc.(AISC)andtheResearchCouncilonStructuralConnections (RCSC)publish theSpecification forStructural JointsusingHighStrengthBolts.Asof thedateof thispaper, the latest versionwaspublishedDecember 31,2009 (theoriginaldocumentwaspublished in 1984). The specification is comprised of ten sections, including General Requirements;Fastener Components; Bolted Parts; Joint Type; Limit States in Bolted Joints; Use of Washers; PreinstallationVerification; Installation; Inspection;andArbitration.These tensectionsminimallyaddresstestingofcoatingsusedintheboltedjoint.Rather,AppendixA,TestingMethodtoDeterminetheSlipCoefficientforCoatingsUsedinBoltedJointscontainsfoursectionsrelatingtocoatingtesting(GeneralProvisions;TestPlatesandCoatingoftheSpecimens;SlipTests;andTensionCreepTests).ThefocusofthispaperisonthecontentofAppendixA.EssentialVariables

Appendix A, Section A1.2 defines Essential Variables as those that, if changed, will requireretestingofthecoatingtodetermine itsmeanslipcoefficient.TheEssentialVariablesarenotdictatedbythespecificationbutrathertheyareestablishedbythecoatingmanufacturerpriortotesting.TherearefourEssentialVariables,including:thecuretime(thetimeintervalbetweencoatingapplicationandtesting),which establishes theminimum curing timeprior to field assemblyof the joint; any specialcuringprocedures(whentheyaredifferentthantheinstructionsprovidedbythecoatingmanufactureron the Product Data Sheet); maximum coating thickness as measured according to SSPCPA 2 (thespecification requires the addition of 2mils dry film thickness to themanufacturers recommendedmaximum thickness for the joints); and the composition of the coating, including the method ofmanufacture and the type and amount of thinner (reducer) to be used (if any). Accordingly, themanufacturer of the coating to be tested must establish the cure time, special curing procedures,maximumcoatingthicknessandthetypeandamountofthinnerwhenrequiredforatomizationand/orpostatomizationflowout.

While themethodofapplication isnot listedasanEssentialVariable,SectionA2.2 (SpecimenCoating)statesthatthecoatingsaretobeappliedtothetestspecimensinamannerthatisconsistentwiththemethod intendedtobeusedonthestructuralapplication.So ifthecoating is intendedtobeappliedbyairlesssprayintheshoporfield,thenthecoatingshouldnotbeappliedbybrush/rollertothetestspecimens.

Unfortunately, Appendix A of the specification does not provide a tolerance for coating

thickness;onlythat2milsmustbeaddedtothecoatingmanufacturersmaximumthickness.So ifthemaximumthicknessis4mils,thetestthicknessis6mils.However,applyingexactly4milsofcoatingtoaroughenedsurface intheshop/field(or6mils inthe laboratory) isessentially impossible.Therefore,areasonablethicknesstolerance(e.g.,0.50.7mil)shouldbeestablishedpriortotesting.Thetestreportmustindicatetheactualthicknessofthecoatingappliedtoeachtestspecimen.

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OtherVariablesforConsideration It is not clear whether the method of surface preparation (e.g., power tool cleaning versesabrasive blast cleaning), surface cleanliness, and surface profile depth and shape influence the slipcoefficientpropertiesofthecoating.Althoughnot listedasanEssentialVariable inAppendixAoftheRCSCSpecification,thereissomedebateastowhethersurfacepreparationshouldbeconsideredwhendoing testing to determine if the type of cleaning (e.g., power tool cleaning verses abrasive blastcleaning),thedegreeofcleanliness(SSPCSP5orSP10versesSSPCSP6)andthesurfaceprofiledepthandshape(e.g.,roundversesangular)affecttheresults.Asapointofreference,AASHTOSpecificationR31forEvaluationofProtectiveCoatingSystemsforStructuralSteelrequiresabrasiveblastcleaningtoachieveaWhiteMetalBlast(SSPCSP5/NACENo.1)using100%S280steelshottoproducea23.5milsurfaceprofilefortheslipcoefficienttest.Steelshotwasselectedtoproduceapeenedsurfacetexture(lowerpeakdensity)tocreateaworstcasescenario.TheAASHTOspecificationdoesnotrequiresimilartestingoverpowertoolcleanedsteel.CorrectionofCoatingThicknessDeficiencies Whencoatingsareappliedintheshopoffieldandthemeasureddryfilmthicknessislessthanspecified,itisacommonpracticetoapplyabuildupcoat(withinthemanufacturersrecoatinterval)toachievethespecifiedfilmthickness.Conversely,ifacoatingisappliedtoothick,sandingorscreeningisusedtoreducetheappliedthickness,orthethickness isnotcorrected(excessivethickness isacceptedbythefacilityowneraftercoatingmanufacturerapproval).Thesecorrectivepracticesalterthesurfaceof the coating (sanding/screening) or present a potentially weakened interface (buildup coat) andshould not be performed on faying surfaces either in the laboratory for testing or in the shop/fieldduring actual application. If thickness deficiencies are found in the faying surface areas, the coatingshouldberemovedandreappliedtothecorrectthickness.UnfortunatelytheRCSCdoesnotspecificallyaddressthisissue.TestPlateDesignandSurfacePreparation Thereare two testplatedesignsdescribed inAppendixA, includinga SlipTestPlateandaTensionCreepPlate.

TheSlipTestPlateisfabricatedfromsteelwithayieldstrengthof3650ksi.Theplatesmeasure4x4x5/8andcontaina1 (1/16)diameterholecentered11/2 fromoneedge.The topandbottomedgesmustbemilledflatandsurfacesoftheplatesmustbeflatenoughtoensurereasonablyfullcontactoverthefayingsurface.Noburrsorotherdefectsarepermitted.

TheTensionCreepTestPlateisfabricatedfromthesametypeandstrengthsteel;howeverthe

platesare larger (4x7x5/8)andcontainatwo1 (1/16)diameterholescentered11/2 fromboth4edges.Thetopandbottomedgesarenotrequiredtobemilledflat,howeverthesurfacesoftheplatesmustbe flatenough toensurereasonably fullcontactover the fayingsurface.Aswas thecasewiththeSlipTestPlates,noburrsorotherdefectsarepermitted.

TensionCreep TestPlate(frontview).Theholeshavebeendeburred.

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SlipTestPlate(frontview).Theholehasbeendeburred.

SlipTestPlate(endview).Theedgehasbeenmilledflat

Prior to mechanical methods of surface preparation, the surfaces are solvent cleaned inaccordancewithSSPCSP1toremovegrease,oilorotherfabrication lubricants.Thefayingsurfacesofthetestplatesaresubsequentlyprepared(e.g.,byabrasiveblastcleaninginthecaseoftheAASHTOR31specification) using the abrasive type and shape required by the coating manufacturer or projectdesigner.Theabrasivesizeshouldnotbedictated,only therequiredsurfaceprofiledepth (e.g.,23.5mils). The laboratory conducting the testingwill select the abrasive size thatwill yield the specifiedprofiledepth.DetailsrelatedtosurfacepreparationareundefinedbytheRCSCspecificationbutmustbereported by the testing laboratory. The edges of the test plates and the holes are not prepared bymechanicalmeans,noraretheycoated.TestPlateMounting,CoatingApplicationandCuringProcedures The procedures for mounting and securing the test plates are not prescribed by the RCSCspecification.However,sincethetestsurfacesmustbefreeofsurfacedefects,specialrackortrayscanbeusedtoholdthetestplatesinplacehorizontally(usingcompressionfitalongthenonmillededges)andso that the facescanbesprayedandcuredhorizontally, inorder topreventrunsandsags in theappliedfilm.Thisisespeciallyimportantsincethespecificationrequirestheadditionof2drymilstothecoatingmanufacturersmaximumthickness(whichmayexceedthesagresistancethicknessforagivencoating).Fifteenslip testplatesandnine tensioncreep testplatesarerequired for testing.Additional(spare)testplatesareoftenpreparedintheeventofasurfacedefectorcoatingthicknessvariation.

Mountingoftensioncreepplatesinrack/tray Slip test plates mounted in rack/tray (ready forapplication)

Coatingmaterialsaremixedandappliedaccording to themanufacturerswritten instructions.Thinner (reducer) ifrequiredby themanufacturer isadded.The typeandamountof thinneradded isregardedasanEssentialVariableandmustbereportedontheCertificateofTesting (described later).Thebatch/lotnumbersofthecoatingcomponentsandthinnerarealsorecordedandlistedonthetestcertificate.Naturally, the same lot/batch tested does not have to be applied in the shop/field. Thecoatingisapplied2mils(dryfilm)thickerthanthemanufacturersmaximumdryfilmthickness.

Application of coating to mounted test plates usingsemiautomated spray arm and an autoairless spraygun

The coatingmust be cured according to themanufacturers recommended conditions of airtemperature, humidity and time. An owner/specifier may require specific curing conditions. Forexample, theAASHTOR31specificationrequirescuringat25+/2Cand65+/5%relativehumidity.Theactualcuretimeisdeterminedbythemanufacturerofthecoatingandcanrangefrom24hoursto14days,even30dayspriortotesting.Conditionsaremonitoredthroughoutthecuringperiodusingarecordinghygrothermographoradigitalpsychrometer(shownbelow).CoatingThicknessMeasurementandSelectionofMatingSurfaces CoatingthicknessismeasuredaccordingtoSSPCPA2,MeasurementofCoatingThicknessUsingMagneticGages.AType2 (electronic)gage (shown) is typicallyused forspeedandaccuracy.Severalspotmeasurements(eachtheaverageofthreegagereadings)areacquiredfromeachcontactface.Theaverageofthemeasurementsforeachcontactsurface isrecordedandreported.Contacttestsurfaceswithconformingcoatingthickness(andwithsimilaraveragethicknessvalues)areselectedandmated.

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Monitoringcuringconditions Measuringcoatingthicknessusingadigitalpsychrometer usingatype2electronicgage

QromaResaltado

TestAssembliesASlipCoefficienttestassemblyconsistsofthreetestplates:acenterplatewithtwocontactsurfacesandtwooutsidetestplateswithonetestsurfaceeach.Fivereplicateassembliesmustbetested,sofivecenter panels and ten outside panels must be selected and mated for the Slip Coefficient test. ATensionCreeptestassemblyissimilar,exceptthatthreereplicateassembliesmustbetested(insteadoffive),sothreecenterpanelsandsixoutsidepanelsmustbeselectedandmated.SlipCoefficientTestProcedure Oncethematingsurfacesareselected(basedonsimilaraveragecoatingthicknessvalues),thetestplatesareloadedontoa7/8threadedrodlocatedinthecenterofahorizontalloadcell.Thecentertestplateisinverted180asitisloadedontotherodsothattheedgeoftheplateishigherthanthetwoendplates.This istheplatethatreceivesthevertical loadduringtesting.A1/8gapbetweentherodandoneedgeofthehole(theholeis1diameter)isestablishedbyliftinguponthecentertestplatesothatthebottomofthehole is incontactwiththebottomofthethreadedrod.Thegap ismaintainedduringclampingusingaspacer.Aclampingforceof49+/0.5kips(49,000+/500psi)isappliedtothetestassemblyusingthehorizontal loadcelloperatedusinghydraulicpressure.This load ismaintainedthroughoutthetestingprocessandismonitoredusingadigitalreadout.

Loadingofassemblyonto7/8threadedrod Electronicdisplaysofclampingforceandslip deflection

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Oncetheclampingforceisapplied,theverticalloadcellplatenisloweredsothatitcontactsthetop (milled) edge of the center test plate. After 1 kip of load is applied to the vertical platen, slipdeflectionmonitoringgagesareattachedandengaged.Theverticalcompressionloadisappliedatarateless thanorequal to25kips/minute (oramaximumof0.003ofslipdisplacementperminute).Eachassemblyonlytakesonlyafewminutestotest.

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Slipcoefficienttestinprocess.Figuresillustratethesimultaneousapplicationoftheclampingforceandtheverticalloadtothecenter(inverted)testplate

Thetestisterminatedwhen0.05ofslip(orgreater)occurs.TheslipdisplacementisdisplayeddigitallyandismonitoredandrecordedonanXYplotter.TypicalslipresponsesareillustratedinSectionA.4oftheRCSCspecification,reproducedbelow.

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Slip displacement curve (a) illustrates themaximum load, provided it occurs before 0.02 ofdisplacement.Slipdisplacementcurve (b) illustratestheslip loadatthepointwhentherate increasessuddenlyandslipdisplacementcurve(c)illustratesthesliploadcorrespondingtodeformationat0.02.Thiscurveindicatestheloadversesslipisgradual,notsuddenaswithcurve(b).

SlipCoefficientCalculation Fivereplicateassembliesaretested.Themeanslipcoefficient(ks)iscalculatedas:ks= SlipLoad____ 2xClampingForceSampledata illustratingthiscalculationareshownbelow.Thefirsttablecontainstheactualslip loads;thesecondtablecontainstheslipcoefficientvaluesaftereachofthesliploadsaredividedbytwotimestheclampingforce.

Result1 Result2 Result3 Result4 Result5 Mean

57,028 56,626 55,118 57,028 56,276 56,415

Note:ValuesareSlipLoads

Result1 Result2 Result3 Result4 Result5 Mean

0.58 0.58 0.56 0.58 0.57 0.58

Note:ValuesareKsorSlipCoefficientTensionCreepTestProcedure Provided theslipcoefficient testing (knownas thestaticshortterm test)producesacceptableresults,thesecondphaseofthetestingisundertaken,whichisthetensioncreeptest.Thistestislongerterm(1,000hoursorsixweeks)comparedtotheslipcoefficienttest.Forthisphaseachainofnine4x7testplatesisassembledusinghighstrengthbolts(ASTMA325orA490bolts).ASTMA490boltsaremorecommonandthereforemorefrequentlyusedinthisprocedure.ThetensioncapacityoftheboltsistestedusingaSkidmoreWilhelmBoltTensionCalibratorpriortoassemblingthechain.Threereplicateassemblies, each consisting of three 4 x 7 test plates are used to create the creep chain.Onceassembled, the plates are bolted together using a calibrated torque wrench with tensionindicatingbolts. Once assembled, the chain is suspended from the tension creep frame (using loose bolt/nutassembliesat the topandbottomof thechain)and thevertical load isappliedusinga loadcell.Theapplied load isbasedon the typeofboltemployedand the slipcoefficientclass that is targeted.Forexample,25.9kips load isapplied forClassAslipcoefficientusingA490bolts,while39.2kips load isappliedforClassBslipcoefficientusingA490bolts.Oncetheprescribedtensionisapplieditislockedinplaceusingalargenut.Thistensionismaintainedthroughoutthetestperiod.

IllustrationfromAppendixAshowing Tensioncreeptest Closeupofmicrometerandthetensioncreepchainassembly inprocess magnetsattachedtoassembly

Speciallymachinedhorizontalmagnetsarepositionedoneachassemblysothattheyareonlyincontactwith the twoouter testplatesandnot thecenter testplate.Verticalmagnetsarepositionedbetweenthetwohorizontalmagnetsandareorientedsotheyareonly incontactwiththecentertestplateandnotthetwooutertestplates.Thepurposeofthemagnetsistoholdthemicrometersinplace.Since themicrometersare incontactwith themagnets (whichare incontactwith theassembly),anycreep will register on the micrometer dial. These micrometers are set to 0 within 30 minutes ofapplyingthe loadandthe load ismaintainedfor42days (1000hours).Anydisplacement (revealedbymovementfromthezeropositiononthemicrometers)isrecordeddaily. Three replicate assemblies are tested concurrently.No single assembly can exceed0.005ofdisplacement. After 1000 hours, the load is again increased to the design slip multiplied by 2x theclampingforce(32.3kipsforClassAand49kipsforClassB).Oncethisfinalloadisapplied,theaveragecreepdisplacementcannotexceed0.015forallthreeassemblies.Sampledataareshownbelow.Notethatthedatarepresentsapassingtestsincenoneoftheassembliesexceeded0.005ofdisplacementandtheaveragecreepdisplacementislessthan0.015forallthreeassemblies.

Assembly1 Assembly2 Assembly3

InitialMicrometerReading 0 0 0

FinalMicrometerReading 0.00175 0.0015 0.0009

CreepDisplacement 0.00175 0.0015 0.0009

AverageDisplacement 0.00098

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Oncethestaticshorttermtest(slipcoefficient)andtensioncreeptesting iscomplete(andthecoating passes both the slip coefficient test and the tension creep test), the coating is classified.AccordingtotheRCRSspecificationthemeanslipcoefficient()canbecategorizedasClassA,BorC.AClassAslipcoefficientrating is0.33(uncoated,cleanmillscaleorcoatingsonabrasiveblastcleanedsteel).A ClassB slip coefficient rating is0.5 (uncoated, abrasiveblast cleaned steelor coatingsonabrasiveblast cleaned steel).A ClassC slip coefficient rating is0.35 (roughenedhotdipgalvanizedsurfaces).Note thatANSI/AISC Specification36010, Specification for Structural SteelBuildings lists0.30slipcoefficientforClassAasopposedto0.33.

A Certificate of Testing accompanies the test report. This Certificate lists the product

manufacturerandname/no.,theClassachieved(ClassA,BorC),thebatchnumbersofthecomponentsandthinner(ifused),theminimumcuretimepriortoboltup,thecuringconditionsofairtemperatureandhumidity,themaximumdryfilmthickness,thetypeandamountofthinnerused (ifany),thetestperiodandtheactualslipcoefficientvalue.Thistestcertificateisveryimportant,asitliststheEssentialVariablesunderwhichtheproductwastestedandclassified,andshouldbearequiredsubmittalfromthecoatingmanufacturerwhohasbeenselectedtoprovidecoatingsforaproject.Further,theproductshould be applied to the faying surfaces in the shop/field in conformance to the listed EssentialVariables.

SampleTestCertificate Note that surfacepreparation (cleanlinessandprofiledepth/shape)arenot listedon the testcertificate(theyarenotconsideredEssentialVariablesbytheRCSCspecification)andtheminimumdryfilm thickness is not listed (only the maximum). The minimum may be established by the coatingmanufacturerontheproductdatasheet.ReviewofSlipCoefficientDatafromThreeGenericCoatingTypes The following tables contain the results of actual slip coefficient testing performed on threegenericclassesofzincrichprimers, includingtwoorganic(epoxyzincrichandmoisturecureurethanezincrich)andethylsilicate inorganiczincprimers.Thetypeofabrasiveusedforsurfacepreparation isindicated for each. The Essential Variables that are included in the data are cure time (up to eightintervals),coatingthickness(uptosevenvariations)andtworeductionvariations(yes/no).Emptyfieldsindicate that the variable has not been tested. More than one manufacturers product may have

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achieved thesameclassification. It isdifficult todrawmanyconclusions from thedatasets,since theproductswere submittedover aperiodof several years and represented variousmanufacturers andevenformulationswithinagivengenericclass(e.g.,zinccontent,solventsystemsandotherdifferencesinrawmaterials).Further,therewaslittleconsistencyincuretimesandthickness,andnotallvariablesweretestedconsistently(e.g.,notallgenericclassesweretestedwithandwithoutreduction).COATINGTYPEINORGANICZINCAbrasive:100%SteelShot

NoReduction ReductionCureTime 3mils 3.5mils 4mils 5mils 6mils 3mils 3.5mils 4mils 5mils 6mils

24Hrs B A B;B 48Hrs Fail A B72Hrs A B;B 5Days B 7Days B;B;B 10days B

COATINGTYPEINORGANICZINCAbrasive:SteelGrit/SteelShotBlend

NoReduction ReductionCureTime 3mils 3.5mils 4mils 5mils 6mils 3mils 3.5mils 4mils 5mils 6mils

24Hrs B B;B COATINGTYPEINORGANICZINCAbrasive:100%SteelGrit

NoReduction ReductionCureTime 3mils 3.5mils 4mils 5mils 6mils 3mils 3.5mils 4mils 5mils 6mils

24Hrs B B;B COATINGTYPEMOISTURECUREDURETHANEZINCAbrasive:100%SteelShot

NoReduction ReductionCureTime 3mils 3.5mils 4mils 5mils 6mils 3mils 3.5mils 4mils 4.5mils 5mils

7Days A

COATINGTYPEMOISTURECUREDURETHANEZINCAbrasive:SteelGrit/SteelShotBlend

NoReductionCureTime 2mils 3.5mils 4mils 5mils 6mils

4Days A;B 7Days A A 28days B

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COATINGTYPEEPOXYZINCAbrasive:100%SteelShot

NoReduction ReductionCureTime 3mils 3.5mils 4mils 5mils 6mils 3mils 3.5mils 4mils 4.5mils 5mils

24Hrs B 48Hrs Fail B 72Hrs A A4Days A 5Days Fail;A;

A;A

7Days Fail A;B Fail;B A 10days A;B A 14days A A 30days A 60days A

COATINGTYPEEPOXYZINCAbrasive:100%SteelGrit

NoReductionCureTime 3mils 3.5mils 4mils 5mils 6mils

24Hrs A;A 7Days A;A;A

COATINGTYPEEPOXYZINCAbrasive:SteelGrit/SteelShotBlend

NoReductionCureTime 3mils 3.5mils 4mils 5mils 6mils

24Hrs B 48Hrs A 4Days B 7Days A B 10days 14days A 19days A;A

ConclusionsfromData Thetablebelowpresentsasummaryofthedata.Basedonaverylimiteddataset,thereappearstobeanoveralltrendingregardingcoatingtypesthatcanattainaClassBslipcoefficientversesaClassAslipcoefficient rating.Basedon thedata set, itappears thatorganic zincprimersgenerallypossessalowerslipcoefficientratingthantheinorganiczinccounterparts;howeverthereareoccasionswhentheorganiczincprimershaveachievedClassBratings.

CoatingType TotalNo.ofTests No.(%)ClassA No.(%)ClassB No.(%)FailA&BInorganicZinc 21 3(14%) 17(81%) 1(5%)Organic(epoxy)Zinc 36 24(67%) 8(22%) 4(1%)Organic(MCU)Zinc 6 4(67%) 2(33%) 0(0%)

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ResearchInitiatives WhilethetestinganddatamanagementproceduresarefairlywelldefinedinAppendixAoftheRCSCspecification(anotedexceptionisitemno.10below),thereappearstobeasubstantialneedforcoatings industryresearchrelatingtothetestplatepreparationandcoatingprocedures.Tenpotentialresearchinitiativesinclude:

1. Whatistheeffect(ifany)ofsurfaceprofileshapeontheslipcoefficientproperties?2. Whatistheeffect(ifany)ofsurfaceprofiledepthontheslipcoefficientproperties?3. Isthereadifferenceinslipcoefficientpropertieswhenacoatingistestedoverasurfacethathas

beenpowertoolcleaned(i.e.,SSPCSP11orSP15)versesabrasiveblastcleaning?4. Isthereacuringwindow(bothaminimumandamaximumsettimepriortoboltup)?5. What is theeffectofusingadifferent typeof thinner (useof amanufacturersalternate for

hot/windyconditions)ontheslipcoefficientproperties?6. Whatistheeffectofusinglesserorgreateramountsofthinner?7. Whatistheeffectofapplyingabuildupapplicationofthecoating?8. Whatistheeffectofscreeningorsandingdowntheappliedcoating?9. Can a Class A or B slip coefficient be achieved when mating an inorganic zinc primer (e.g.,

appliedtoanewgussetplate inashop)toafieldappliedorganiczincprimeronexistingsteelduringmaintenanceofastructure(thatmayhavedifferentthicknessrequirements)?

10. Sincefivereplicateassembliesaretestedforslipcoefficientthenaveragedtogenerateasingleslip coefficientvalue,what is theacceptable standarddeviationbetween the replicate trials?Thatis,whatdeterminesanoutlier?