ACI 222.2R-01 Corrosion of Prestressing Steels

ACI222.2R-01becameeffectiveFebruary1,2001.Copyright©2001,AmericanConcreteInstitute.Allrightsreservedincludingrightsofreproductionanduseinanyformorbyanymeans,includingthemakingofcopiesbyanyphotoprocess,orbyelectronicormechanicaldevice,printed,written,ororal,orrecordingforsoundorvisualreproduc-tionorforuseinanyknowledgeorretrievalsystemordevice,unlesspermissioninwritingisobtainedfromthecopyrightproprietors.ACICommitteeReports,Guides,StandardPractices,andCommentariesareintendedforguidanceinplanning,designing,executing,andinspectingconstruction.Thisdocumentisintendedfortheuseofindividualswhoarecompetenttoevaluatethesignificanceandlimitationsofitscontentandrecommendationsandwhowillacceptre-sponsibilityfortheapplicationofthematerialitcontains.TheAmericanConcreteInstitutedisclaimsanyandallre-sponsibilityforthestatedprinciples.TheInstituteshallnotbeliableforanylossordamagearisingtherefrom.Referencetothisdocumentshallnotbemadeincon-tractdocuments.Ifitemsfoundinthisdocumentarede-siredbytheArchitect/Engineertobeapartofthecontractdocuments,theyshallberestatedinmandatorylanguageforincorporationbytheArchitect/Engineer.222.2R-1CorrosionofPrestressingSteelsACI222.2R-01Thisreportreflectsthecurrentunderstandingofcorrosionofprestressingsteelsinconcrete.Thereportincludeschaptersthatcoverthevarioustypesofprestressingsteel,includingsomediscussiononmetallurgicaldiffer-ences.Deteriorationmechanismsarediscussed,includinghydrogenembrittlementandstress-corrosioncracking.Methodstoprotectprestress-ingsteelagainstcorrosioninnewconstructionarepresented,alongwithadiscussionoffieldperformanceofprestressedconcretestructures.Finally,fieldevaluationandremediationtechniquesarepresented.Keywords:anchorage;corrosion;duct;durability;grout;hydrogenembrit-tlement;post-tensioned;prestressed;strand;stress-corrosioncrack-ing;tendon;unbonded.CONTENTSChapter1—Introduction,p.222.2R-21.1—Background1.2—ScopeChapter2—Prestressingsteels,p.222.2R-32.1—Wire2.2—Strand2.3—BarChapter3—Deteriorationofprestressingsteel,p.222.2R-43.1—Introduction3.2—Deteriorationofprestressingsteels3.3—Metallurgyofprestressingsteels3.4—Stress-corrosioncrackingandhydrogenembrittlement3.5—Casehistories3.6—Stress-corrosioncracking3.7—Hydrogenembrittlement3.8—Corrosioneffectonfatigueperformance3.9—TestingforSCCandHEChapter4—Protectionagainstcorrosioninnewconstruction,p.222.2R-154.1—IntroductionReportedbyACICommittee222TheodoreBremnerDavidManningArpadSavolyStevenDailyEdwardMcGettiganWilliamScannellMarwanDayeRichardMontaniMorrisSchupack*EdwinDeckerMohamadNagiKhaledSoudkiRichardDidelotTheodoreNeffDavidTrejoBernardErlinKeithPashinaThomasWeilPingGuWilliamPerenchioJeffreyWest*†TreyHamilton*†RandallPostonRichardWeyersKennethHoverRobertPriceDavidWhiting‡ThomasJosephD.V.ReddyJeffreyWouters*†MohammadKhanBrianB.Hope*ChairmanCharlesK.NmaiSecretary*Subcommitteemember.†Primaryauthor.‡Deceased.Note:Consultingmember—RichardLewis.222.2R-2ACICOMMITTEEREPORT4.2—Prestressingtendonmaterialsselection4.3—Corrosionprotectionforprestressingsystems4.4—CathodicprotectionChapter5—Fieldevaluation,p.222.2R-255.1—Introduction5.2—Evaluationgoals5.3—Pretensionedsystems5.4—Post-tensionedsystemsChapter6—Remediationtechniques,p.222.2R-306.1—Introduction6.2—General6.3—Groutedpost-tensionedsystems6.4—Ungroutedpost-tensionedsystemsChapter7—Fieldperformanceofprestressedconcretestructures,p.222.2R-327.1—Introduction7.2—Corrosionofprestressingstrandbeforeconstruction7.3—Pretensionedstructures7.4—Unbondedpost-tensionedstructures7.5—Bondedpost-tensionedstructuresChapter8—References,p.222.2R-388.1—Referencedstandardsandreports8.2—CitedreferencesCHAPTER1—INTRODUCTION1.1—BackgroundWhileseveralattemptsweremadeduringthe1800stopre-stressconcrete,themoderndevelopmentofprestressedcon-creteiscreditedtoE.FreyssinetofFrancein1928(LinandBurns1981).Freyssinetunderstoodtheimportanceofusinghigh-strengthsteelforprestressingtoavoidprestressinglossesthatcansignificantlyreducetheappliedprestressingforce.UseofprestressedconcretebeganintheUnitedStateswithcircular-wrappedprestressedtanksin1941(Schupack1964).ThefirstprestressedbridgeintheUnitedStateswaslocatedinTennesseeandopenedtothepubliconOct.28,1950.TheWalnutLaneBridge,locatedinPennsylvania,wascompletedinthefallof1950andopenedtotrafficinFeb.1951(Manning1988).Sincethattime,applicationsofprestressinginbridgeandbuildingconstructionhavespreadrapidly.IntheUnitedStatesprestressedconcretehasproventobeaverysuccessfulmethodofconstruction.Itsbenefitsincludeincreasedload-bearingcapacity,improvedcrackcontrol,andslendernessofelements.Corrosionisnotaswelldocumentedinprestressedcon-cretestructuresasinnonprestressedconcretestructures.Corrosionofthesestructuresappearstoberestrictedtospe-cificcircumstances,includingconstructiondetails,improperdesign,andconstructionpractices.Thepotentialforwide-spreadproblemsstillexists,however.Indeed,inenviron-mentscontaminatedwithknowncorrosionpromoters,suchaschlorideionsandhydrogensulfide,itisimperativethatprestressingsteelbeprotected.Anumberofsurveysprovideinformationconcerningth