2018 01 17 PCINE Guidelines for Resolution of Non ... · Duane Carpenter New York State DOT, Albany, NY Michael Twiss New York State DOT, Albany, NY ... materials, and repairs of

GuidelinesforResolutionofNon-ConformancesinPrecastConcreteBridgeElements

ReportNo:PCINE-18-RNPCBE

FirstEdition

Report No: PCINE-18-RNPCBE Title: Guidelines for Resolution of Non-Conformances in Precast Concrete Bridge Elements Developing Organization: Precast/Prestressed Concrete Institute Northeast Bridge Technical Committee Phone – 888-700-5670 Email – [email protected] Report Date: 1-16-18 Revision Dates: Status of Report: Final Abstract: These guidelines provide recommendations for the evaluation and repair of non-conformances in precast and prestressed concrete bridge products. The document can serve as a resource for owners, designers, state inspectors, plant production managers, plant quality control Inspectors and plant engineers in reaching informed decisions in addressing non-conformances and repairs. Number of Pages: 89 PCI and PCI Northeast cannot accept responsibility for any errors or oversights in the use of this material. The user must recognize that no guidelines or regulations can substitute for experienced judgment. This guideline is intended for use by personnel competent to evaluate the significance and limitations of its contents and able to accept responsibility for the application of the material it contains.

Guidelines for Resolution of Non-

Conformances in Precast Concrete Bridge Elements

Report Number PCINE-18-RNPCBE

GuidelinesforResolutionofNon-ConformancesinPrecastConcreteBridgeElements

ReportNo:PCINE-18-RNPCBE

Copyright©2018

ByPrecast/PrestressedConcreteInstituteNortheastFirstEdition

ThisdocumentsupersedesthedocumenttitledPCINER-01-BMRG–BridgeMemberRepairGuidelinesdatedOctober2001

Allrightsreserved.Thisguideoranypartthereofmaynotbereproducedinanyform

withoutthewrittenpermissionofthePrecast/PrestressedConcreteInstituteNortheast.

PrintedintheU.S.A

These guidelines should not be considered a standard. Information contained in thisworkhasbeenobtainedfromsourcesbelievedtobereliable.PCIandPCINortheastoritsmembershipsshallnotberesponsibleforanyerrors,omissions,ordamagesarisingoutof this information.PCINortheasthaspublishedthisworkwiththeunderstandingthat PCI Northeast is supplying information only. PCI Northeast is not renderingengineeringorotherprofessionalservicesthroughtheseguidelines.Ifsuchservicesarerequired,pleaseseekanappropriateprofessional.

ContentsForeword........................................................................................................................................1

Section1:Introduction...................................................................................................................2

Howtousethismanual..............................................................................................................2

FinishingofPrecastElements.....................................................................................................3

GradeAFinish.........................................................................................................................3

GradeBFinish(highlyvisible).................................................................................................4

StandardGradeFinish(exposedtoview)...............................................................................4

CommercialGrade(notexposedtoview)..............................................................................4

UnformedSurfaceFinishes.....................................................................................................4

ExposedAggregateFinishesforElementConnections...........................................................5

SpecifyingSurfaceFinishes.....................................................................................................5

SurfaceRepairs.......................................................................................................................5

RepairDecisionProcess..............................................................................................................5

RecommendedDecisionProcessFlowchartKeyFactorsinDecisionsRegardingNoRepair,Repair,orRejection................................................................................................................6

GeneralCommentsonCracking.............................................................................................7

SpallsandVoids......................................................................................................................8

DurabilityofRepairs...............................................................................................................9

EssentialIssuestoBeConsideredInEngineeringEvaluation.................................................9

RepairableNon-conformances.............................................................................................11

Non-RepairableNon-conformances.....................................................................................11

Section2:TroubleshootingGuide................................................................................................12

Section2.1:PrestressedElements............................................................................................12

TS#1:TROUBLESHOOTINGFORTRANSVERSECRACKSORIGINATINGATTOPSOFBEAMS 14

TS#2:TROUBLESHOOTINGVERTICALANDDIAGONALCRACKSATBOTTOMOFBEAMS...17

TS#3:TROUBLESHOOTINGVERTICALTHROUGHCRACKSINBEAMS..................................20

TS#4:TROUBLESHOOTINGHORIZONTALENDCRACKSINWEBSANDFLANGES................22

TS#5:TROUBLESHOOTINGBOTTOMFLANGECRACKSATBEAMENDS..............................24

TS#6:TROUBLESHOOTINGCORNERSPALLSORCORNERCRACKS......................................25

TS#7:TROUBLESHOOTINGPARTIALLYCRACKEDTOPFLANGES.........................................28

TS#8:TROUBLESHOOTINGRANDOMHONEYCOMBINGANDVOIDS..................................30

TS#9TROUBLESHOOTINGRANDOMTOPFLANGECRACKS................................................32

TS#10TROUBLESHOOTINGSHORTPROJECTEDSTRANDORREINFORCING,MISSINGPROJECTEDSTRANDORREINFORCING.................................................................................34

TS#10TROUBLESHOOTINGSHORTPROJECTEDSTRANDORREINFORCING,MISSINGPROJECTEDSTRANDORREINFORCING.................................................................................35

TS#11TROUBLESHOOTINGCRACKSANDHONEYCOMBINGINPRECAST,PARTIALDEPTH 36

DECKPANELS........................................................................................................................36

TS#12TROUBLESHOOTINGPARTIALLYCRACKEDTOPFLANGES–NEXTBEAMS................38

Section2.2:Non-PrestressedPrecastElements...........................................................................41

TS#SS1:TROUBLESHOOTINGCORNERSPALLSINNON-PRESTRESSEDPRECAST...............42

ELEMENTS.............................................................................................................................42

TS#SS2:TROUBLESHOOTINGFORCRACKSINNON-PRESTRESSEDPRECASTELEMENTS...44

TS#SS3:TROUBLESHOOTINGFORHONEYCOMBING,VOIDS,POURLINES,ANDMINOR..46

SURFACEIMPERFECTIONSINNON-PRESTRESSEDPRECASTELEMENTS...............................46

TS#SS4:TROUBLESHOOTINGSHORTPROJECTEDREBARANDMISSINGPROJECTED........48

REBARINNON-PRESTRESSEDPRECASTELEMENTS..............................................................48

TS#SS5:TROUBLESHOOTINGMISSINGORMIS-LOCATEDINSERTS,VOIDS,ORMIS-LOCATEDPROJECTINGREBARINNON-PRESTRESSEDPRECASTELEMENTS.........................50

Section2.3:PrecastFullDepthDeckPanels.............................................................................52

TS#FDDP1:TROUBLESHOOTINGCORNERSPALLSINPRECASTFULL-DEPTHDECKPANELS53

TS#FDDP2:TROUBLESHOOTINGFORCRACKSINFULL-DEPTHPRECASTDECKPANELS.....55

TS#FDDP3:TROUBLESHOOTINGFORTRANSVERSECRACKSINPRESTRESSEDFULL-.........57

DEPTHDECKPANELS.............................................................................................................57

TS#FDDP3:TROUBLESHOOTINGFORTRANSVERSECRACKSINPRESTRESSEDFULL-.........58

DEPTHDECKPANELS.............................................................................................................58

TS#FDDP4:TROUBLESHOOTINGFORHONEYCOMBING,VOIDS,ANDMINORSURFACE...59

IMPERFECTIONSINPRECASTFULL-DEPTHDECKPANELS.....................................................59

TS#FDDP4:TROUBLESHOOTINGFORHONEYCOMBING,VOIDS,ANDMINORSURFACE...60

IMPERFECTIONSINPRECASTFULL-DEPTHDECKPANELS.....................................................60

TS#FDDP5: TROUBLESHOOTINGSHORTPROJECTEDREINFORCINGANDMISSING.......61

PROJECTEDREINFORCINGINPRECASTFULL-DEPTHDECKPANELS.....................................61

TS#FDDP6: TROUBLESHOOTINGMISSINGORMISLOCATEDINSERTS,VOIDS,DUCTSORMISLOCATEDPROJECTINGREINFORCINGINPRECASTFULL-DEPTHDECKPANELS..............64

Section3:StandardRepairProcedures........................................................................................66

STANDARDREPAIRPROCEDURE#1FORCONFINEDSPALLSINSIDEBEARINGAREAS..............67

STANDARDREPAIRPROCEDURE#2FORCONFINEDSPALLLSOUTSIDEBEARINGAREAS.........68

STANDARDREPAIRPROCEDURE#3FORNON-CONFINEDBEARINGAREASPALLS..................69

STANDARDREPAIRPROCEDURE#4FORSPALLSANDVOIDSINTHEBOTTOMFLANGETHATEXPOSEPRESTRESSINGSTRAND...............................................................................................70

STANDARDREPAIRPROCEDURE#5FORHONEYCOMBEDORVOIDEDWEBAREAS................72

STANDARDREPAIRPROCEDURE#6FORDAMAGEDFLANGESREQUIRINGREMOVALANDREPLACEMENTOFCONCRETE..................................................................................................73

STANDARDREPAIRPROCEDURE#7FORTAKINGCORESANDPATCHINGCOREDHOLESINGIRDERS....................................................................................................................................74

STANDARDREPAIRPROCEDURE#8FORMISSHAPENBEARINGRECESSES..............................75

STANDARDREPAIRPROCEDURE#9FORHONEYCOMBEDAREASLEFT-IN-PLACE....................76

STANDARDREPAIRPROCEDURE#10FOREPOXYINJECTIONOFCRACKS................................77

STANDARDREPAIRPROCEDURE#11FORSHORTPROJECTINGMILDREINFORCINGBARSORPROJECTINGPRESTRESSINGSTRANDS.....................................................................................79

STANDARDREPAIRPROCEDURE#12FORREPLACEMENTOFMISSINGPROJECTEDMILDSTEELORPRESTRESSINGSTRAND.......................................................................................................80

STANDARDREPAIRPROCEDURE#13FORMISSINGORINCORRECTLYLOCATEDDIAPHRAGMINSERTS.....................................................................................................................................81

STANDARDREPAIRPROCEDURE#14FORSEALINGCRACKS....................................................82

STANDARDREPAIRPROCEDURE#15FOREDGESPALLSINPRECASTELEMENTS.....................84

Section4:References...................................................................................................................86

1

Foreword These guidelines have been prepared by the Precast Prestressed Concrete Institute Northeast Bridge Technical Committee and contain recommendations for resolution of non-conformances in precast concrete bridge elements occurring during production, handling, transportation and erection. These guidelines are a resource document for owners, designers, state inspectors, plant production managers, plant quality control inspectors and plant engineers in reaching informed decisions regarding non-conformances and repairs. The PCI Northeast would like to acknowledge the members of the Bridge Technical Committee that contributed to the development of these guidelines. RitaSeraderian PCINortheastExecutiveDirector(PCINE);Belmont,MAMichaelP.Culmo CMEAssociates,Inc.,EastHartford,CTEricCalderwood CalderwoodEngineering,Richmond,MEEdBarwicki LinAssociates;Boston,MADarrenConboy JacobsEngineering,Boston,MAJohnByatt CLDEngineers,Manchester,NHScottHarrigan FortMillerGroup,Schuylerville,NYBryanReed ConnecticutDOT,Newington,CTBenCota GCPAppliedTechnologies;Cambridge,MAPaulMoyer GillEngineering;Needham,MAJoeCarrara J.P.Carrara&Sons,Middlebury,VTBrianReeves MaineDOT;Augusta,MERichardMeyers MaineDOT;Augusta,MEMauraSullivan MassachusettsDOT,Boston,MAAlexBardow MassachusettsDOT,Boston,MAEdmundNewton MassachusettsDOT(retired),Boston,MAMichaelMerlis MassachusettsDOT,Boston,MAJasonTremblay NewHampshireDOT,Concord,NHDavidScott NewHampshireDOT,Concord,NHDuaneCarpenter NewYorkStateDOT,Albany,NYMichaelTwiss NewYorkStateDOT,Albany,NYTroyJenkins NortheastPrestressedProducts,LLC,Cressona,PAChrisFowler OldcastlePrecast,Rehoboth,MAMikeSavella RhodeIslandDOT,Providence,RITerrySeymour UnistressCorp.,Pittsfield,MARobYoung VermontAgencyofTransportation,Montpelier,VT

2

Section1:IntroductionPlant-cast prestressed concrete bridge beams and similar products produced in PCI-Certifiedplantsaremanufacturedinaquality-controlledenvironment.Thesefacilitiesmeettheminimumstandards for processes and equipment. They have trained supervisory and certified qualitycontrol staff operating within published procedures that consistently result in high qualityproductsthatmeetprojectandcustomerrequirements.

As with anymanufacturing process, damage or defects can occur in precast concrete bridgeproducts. Examples include surface voids, spalls, cracks in concrete, and improperlyplacedordamagedreinforcementandhardware.Thesefallintooneofthreecategories:

• Productsthatcanbeacceptedwithoutrepair• Productsthatcanbeacceptedwithrepair• Productsthatmustberejected

Thismanualhasbeenpreparedtobearesourcedocumenttoprovideaguidelineforowners,designers, inspectors, and fabricators in reaching informeddecisions regarding repairoptions.To this end, the engineering considerations related to individual defects are provided. Theultimatevalueofthisguidedependsonthesoundengineeringjudgmentofqualifiedindividualswhousethisdocument.

HowtousethismanualThis document is a guideline document that contains recommendations for evaluation andrepair of non-conformances. Owners should consider modifying specification language toincorporatetheserecommendationsintocontractdocuments.

The management of non-conformances is a collaborative process between the Owner (orDesigner) and the Contractor (or Fabricator). At the beginning of a fabrication process, afabrication pre-productionmeeting with all parties involved is recommended. Thismeetingshould establish the process formanaging non-conformances and the responsibilities of eachparty.Thefollowinginformationshouldbediscussedatthepre-productionmeetingregardingthemanagementofnon-conformances:

• Surfacefinishrequirementso Descriptionofacceptablesurfacefeatureso Establishmentofstandardfinishingprocedures

• Repairprocedureso ReviewofPCIRepairManualo Establishacceptablerepairmaterialso Establishpre-approvedownerrepairprocedureso Establishpre-approvedfabricatorrepairprocedures

• DefineresponsibilitiesandNCRprocesso ReviewtheRepairDecisionProcess(flowchart)containedherein

Thereareother itemsthatshouldbediscussedsuchascuringmethods,handlingandstorage,etc.

3

Thesectionsofthismanualareorganizedasdescribedbelow:

Section1: Introduction: Containsgeneral informationon standard finishingprocedures,non-conformancesandmethodsformanagementofnon-conformances. Thissectionalsocontainssignificant informationon the repairprocessand thekey factors that shouldbeconsidered intherepairdecisionprocess.

Section 2 - Troubleshooting Guide: Contains descriptions, by category, of the defect beingconsidered,withcommentaryinside-by-sidecolumns:

• Causes-alistingofpossiblecausesofspecifictypesofdefects• Prevention-correspondingcorrectiveactionstoaidinpreventingeachtypeofdefect• EngineeringEffects -adiscussionof theengineering implicationof thespecific typeof

defecttoprovidethebasisfordecisionsregardingtheoptionofrepairorrejection• Repair Considerations - suggested repair options based upon the Engineering Effects

discussion,withcross-referencestoStandardRepairProcedures(Section3).

Section3-StandardRepairProcedures:Containsspecificinstructionstoimplementrepairsforthevarioustypesofdefectsidentified.

Section 4 - Selected References: Lists sources for additional information on fabrication,materials,andrepairsofprecastandprestressedconcreteproducts.

FinishingofPrecastElementsFinishing refers to the process of stripping the element from the forms, cutting of strandextensions, repair of exposed reinforcing coatings, and providing a uniform appearance tosurfacesthataretobeexposedinthecompletedstructure.Therepairproceduresoutlinedinthis document are not applicable to the finishing process. The minor surface imperfectionsdescribed below are not considered defects and are part of the normal casting and finishingprocess.Itemssuchassmallsurfacevoidsasdescribedinthefinishgradesbelowarearesultofthe process of placing and consolidating high strength, low slump concrete that is commonlyusedinmodernprecastplants.Theuseofself-consolidatingconcretecanbeusedtoreducethenumberofsurfacevoids;however,finishingwillstillberequired.

Standardfinishingprocessescanbedevelopedandagreedtoviathefabricationplant’sQualitySystemManual(QSM).ThefabricatorwillworkwiththeOwner’srepresentativetoidentifyanddocument the standard finishing process to be performed for typical minor surfaceimperfections without the necessity of filing, reviewing, and approving a Non-ConformanceReport(NCR).

Thefollowingfinishdescriptions,takenfromAppendixCofPCIMNL116,maybeusedtodefinespecification requirements. Theminimum finish grade consistentwith a product’s applicationandtheintendeduseofthestructureshouldbespecified.

GradeAFinishGradeAFinish is foruse inspecialarchitecturalapplicationsandnotrecommendedforbridgeproducts.

4

GradeBFinish(highlyvisible)Allairholesover1/4inchinsizeshouldbefilled.Airholesbetween1/8and1/4inchinwidththatoccur in high concentration (more than one per 2 square inches) should be filled. Surfaceblemishesduetoholesordentsinformsshouldberepaired.Discolorationshouldbepermittedatformjoints.

Thisfinishisrecommendedforvisuallyexposedstructuralmemberssuchasfasciabeams.

StandardGradeFinish(exposedtoview)Small surfaceholes causedbyairbubbles (“bug-holes”),normal color variations,normal formjointmarks,andminorchipsandspallsshouldbeconsideredacceptable.

No air holes (bug holes) larger than ½ inch in any direction should be permitted. Air holesbetween¼and3/8inchinwidththatoccurinhighconcentration(morethanoneper2squareinches)shouldbefilled.Large,unsightlysurfaceblemishesorhoneycombingshouldberepaired.Themaximumallowableformjointoffsetshouldbelimitedto1/8inch.Thisfinishmaybeusedwhereproductsareexposedtoviewbutthefunctionofthestructuredoesnotrequireaspecialfinish.Thesurfaceshouldbesuitableforanappliedtexturedcoatingbutnotnecessarilysuitableforpainting.

Thisistherecommendedfinishgradeforallstructuralproductsthatarevisibleinthecompletedstructure.

CommercialGrade(notexposedtoview)Thisisessentiallyan“ascast”finish.Concretemaybeproducedinformsthatimpartatextureto the concrete, (e.g., plywood lumber or steel formswith offset joints, dents or holes). Thesurfacemaycontainairholes(bugholes)andwatermarks,andtheremaybesomeminorchipsand spalls. Theremaybe some scaling and/or scouring. Theremaybepatches and streaksofcolorvariationwithinthesurface,andtheoverallcolortonemayvarybetweenpieces.

Large fins from joint bleeding should be removed, but small fins may remain. Only“honeycombed”and/orbadlyspalledareasshouldberepairedorfinished.Allfacesshouldhavetrue,well-definedsurfaces.Themaximumallowable form jointoffsetshouldbe limitedto3/16in.

This finish is recommended for surfaces of products that are not visible in the completedstructure,orwhenthefunctionofthestructuredoesnotrequireanenhancedsurface.

UnformedSurfaceFinishesThesetypesoffinishesareobtainedbyscreedingandfloatingwithadditionalhandfinishingatprojections. Normal color variations, minor indentations, minor chips, and spalls should bepermitted. No major imperfections, honeycombing, or defects should be permitted. Whereuniformityorotherspecial characteristicsofexposed,unformedsurface finishesare required,specificationsshouldbeclearontheexpectedresults.TheManualforQualityControlforPlantsandProductionofStructuralPrecastConcreteProducts,FourthEdition,MNL-116canbeusedforguidanceonsurfacefinishes.

5

ExposedAggregateFinishesforElementConnectionsExposedaggregatefinishesarerecommendedforthesurfacesoftheelementsthatarewithinthe connections in closure joints to improve the bond of grouts and concretes used in theconnections.Anexposedaggregatefinishcanbecreatedinseveralways:

1. A gelatinous retarder can be applied to the formwork in locationswhere the finish isdesired.Thehydrationreactionofthefreshconcretecontactingtheretarderisdelayed.Afterformremoval,theun-hydratedpastecanbewashedwithwater(ifepoxybarsarepresentinthejoint).

2. Sandblastingorhighpressurewaterblastingcanbeapplied to the formedsurface toexposetheaggregate;however,coatedbarswillneedtobeprotected.

The final finish of an exposed aggregate surface is different than the finish of the top of acomposite beam where a certain amplitude is often specified based on design specificationprovisions. Where joints aredetailedwithmechanical shear keys, a specific amplitude is notrequired.Thegoalofexposedaggregatefinishistoexposethestoneandremoveanysurfacelaitance.

SpecifyingSurfaceFinishesThe designer should identify the required surface finishes for all elements based on therecommendationscontained inthisdocument. Plansshould includeascheduleofallelementsurfaces along with the required surface finish. If the plans do not specify finishes, therecommendationscontainedhereinshouldbefollowed.

SurfaceRepairsAny surface variation that exceeds the limits stated above should be considered a non-conformanceandshouldbetreatedasdescribedinSection2.

RepairDecisionProcessTheevaluationofprecastelementsshouldfollowaprescribedprocesswherepotentialnon-conformancesaresystematicallyreviewedbythefabricator’sstaffandowner’srepresentative(inspector).Thefollowingflowchartisarecommendedprocessthatcanbeusedtoefficientlymanagethedispositionofnon-conformancesandrepairs.Thegoaloftroubleshootingshouldbetoresolvethenon-conformanceasclosetotheshopflooraspossible.ManyitemsmayberesolvedbetweentheshopQCManager,plantengineer,andtheOwner’sinspector.Thisdocumentalsogivesguidanceonwhenanon-conformancerequiresinputfromtheEngineer.

6

RecommendedDecisionProcessFlowchart

Legend

NCR=Non-ConformanceReport

Non-ConformanceNotedintheShopbyQCStafforOwner's

Representative

Non-ConformanceReviewedbyShopQCManagerStaff

ReviewTroubleshootingGuidelineand/orPre-approvedRepairProceduresforApplicability

IsdamageapplicabletoaTroubleshooting

Guideline?

IssueNCR(ownerorfabricator).SubmitProposedRepairProcedure toOwnerfor

approval.

No

Yes

ReviewTroubleshootingGuideline

DetermineMostProbableCause

DetermineMethodofPrevention

ReviewEngineeringEffects

ReviewPotentialRepairMethods

ReviewwithOwner'sRep.

IstheNon-Conformanceminor,

notrequiringdesignerinput?

Yes

FollowRepairProcedureOutlinedinTroubleshootingGuidelineorFabricator'sPre-

approvedRepairProcedure

No

ReviewandapproveRepairprocedureifacceptable

FabricatorStaff

Owner

Fabricator&Owner'sRep.

ActionItemProcessStep

Decision

IssueNCR(ownerorfabricator).SubmitProposedRepair Procedure toOwnerfor

approval.

ReviewandapproveRepairprocedureifacceptable

CantheNon-Conformancebeaddressedwithfinishing orowner

specified standardrepairprocedures?

No

YesFollow FinishingProceduresorOwnerSpecified

StandardRepairProcedures

7

KeyFactorsinDecisionsRegardingNoRepair,Repair,orRejectionEveryefforthasbeenmade toprovidea listof the common typesofdamageordefects thatmay occur in precast and prestressed concrete products during production, handling,transportation,anderection(pre-servicedamage).Othertypesofdefectsordamagemayoccur,however.Theremayalsobeothercauses for the typesofoccurrences listed in thisguideline,othermethodsforprevention,andotherissuestobeconsideredintheengineeringevaluationof thedamage.Engineering judgment shouldbeexercised in thesesituations. Inaddition, theapproachesillustratedinthisguidelinecanbeappliedtoothersimilarsituationsthatmayarise.

Decisions regarding the need for repair or rejection should be established by the owner andincludedinthecontractdocuments. Thereisasignificantcost impactforthefabricator. Ifallbiddersunderstandthatcertaindefectswillnotrequirerepair,orthatstandardrepairsmaybeapplied without the need for excessive review and documentation, the Owner could benefitwith lower bids. The converse, of course, is also true. Defining repair requirements alsobenefitstheOwnerbyreducingthenumberoftime-consumingnon-conformancesthatmustbeevaluated.

Proper design, detailing, and fabrication techniques are essential for the production of high-qualityprecastandprestressedconcreteproducts.Someofthemanyproceduresandprocessesincludeconcretemixdesign,mixingandconsolidationofconcrete,curingofconcrete,methodsandmaterialsfordebondingstrands,placementofdebondedstrands,methodsandsequencesofdetensioningofstrands(includingspecialconsiderationsforharpedordrapedstrands),anddetailing of anchorage zone reinforcement. Discussion of the important aspects for each ofthese issues that contribute to defects or damage to elements is beyond the scope of thisdocument. Additional information on these topics may be found in the PCI Quality ControlManual[1]andthePCIBridgeDesignManual(Section3,Fabrication)[2].

GeneralCommentsonCrackingWhen cracks occur, their cause, effect, and possible consequences must be determined. Astructuralevaluationmayberequireddependingonthenatureandlocationofthecrack.Therepairguidelinescontainedhereinincluderecommendationsforwhenastructuralevaluationiswarranted.

Cracks may occur in sections of prestressed concrete girders where the effects of theprestressingforcedonotdirectlyacttoclosesuchcracks.Itshouldbeunderstoodthatgirdersareprestressed intheir long,axialdirection.Therefore, ingeneral,anycracksthatforminthegirderthatareroughlyparalleltothelongaxisofthememberwillnotcloseundertheeffectofprestressing. An example of such cracking is the horizontal and/or diagonal splitting thatsometimesoccursattheendsofmembers(seeSection2,TS#4).

Cracksperpendiculartothelongaxisofthemembercanoccurpriortotransferoftheprestressforce when the concrete is not yet prestressed. At this time, the strands and forms providerestrainttodimensionalchangesintheconcreteduetoshrinkageandthermalcontraction(seeSection2,TS#3).However,whenthestrandsaredetensioned,thesecracksgenerallycloseduetotheprestressforce.

8

Ifthecracksclosewhenthestrandsaredetensioned,orwhenrestraintsorotherconditionsthatcaused the cracks are resolved prior to de-tensioning, the consequences of the cracking aregenerally minor or nonexistent. The phenomenon of autogenous healing can result in theconcrete "healing" through the crack, reestablishing the tensile capacity of the concrete andrestoringittoitsun-crackedcondition.Ifallowedtoclosewithouttangentialdisplacement,finecracks in fractured concrete, in the rangeof 0.004 in. to0.008 in.wide,will close completelyundermoist conditions.This isespecially true in thepresenceof compressivepressureacrossthe crack. Crackswith a 0.004 in.width can heal over a period of several days,while cracks0.008in.inwidthcanhealoveraperiodofseveralweeks.Thisautogenoushealingisduetothehydrationofpreviouslyun-hydratedcement.Ithasbeenshownthatcrackshealedautogenouslywillperformstructurallyandlong-termlikeun-crackedconcrete.

If the cracks remain open after detensioning, or if they open after detensioning, severalscenariosmustbeconsidered:

• Willthecrackclosewhensubjectedtosubsequentloadsonthestructuresuchasbytheadditionofabridgedeck?

• Willthecrackbeprotectedbyacompositedeck,orotherencasement,fromwaterandsaltthatmaybeplacedonthedeck?

• Isthecracklocatedwithinthetransferlengthofthestrand,inwhichcasethestressinthestrandmaybereducedbythepresenceofthecrack?

• Is thecrack largeenough topermitentryofmoistureandoxygen that couldpromotecorrosionofthestrandsorotherreinforcement?

SpallsandVoidsVoidsor honeycombsmayoccur in the castingof precast andprestressed concreteproducts,especiallybeams,dueto inadequateconsolidationoftheconcrete.Goodconsolidationresultsfrom a good concretemix design, propermixing and placing of concrete, appropriate coarseaggregatesize,aswellasasectionthatisnotoverlycongestedbyprestressingstrandandmildreinforcing steel. Every effort should be taken to detect voids prior to detensioning so thatrepairs,ifpermitted,canbemade,thencuredandpre-compressedwiththeadjacentconcrete.Thisactionensuresthedesignperformanceofthebeamandenhancesthelong-termdurabilityof the repair. Furthermore, the repair of large voids can prevent subsequent damage to thebeamfromdetrimentalredistributionofstressescausedbycross-sectionalvariationsduringthedetensioningprocess.

Promptinspectionofbeamspriortodetensioningisveryimportantbecausedelayintransferoftheprestresscanleadtodamagefromcracking.Crackscanoccurwhenbeamscoolwhiletheyareanchoredtoabutmentsbytheprestressingstrands.Wheninspectiondetectsvoidsorsignsof potential internal voids, measures should be taken during repair investigations to controlconcretecontractionorshorteningoftheexternalprestressingstrandduetocooling.Methodsforinvestigatingthepresenceorextentofinternalvoidsincludesoundingwithhammers,usingpulse-echoequipment,andprobingwithwireorbydrillingexploratoryholes.

9

DurabilityofRepairsThegoalofallrepairsistoprovideanelementthathasequivalentdurabilitywhencomparedtothe adjacent element concrete. The repair procedures contained herein, when constructedcorrectly, haveproven tomeet this goal. Thepresenceofa repair shouldnotbe cause for areductionintheelement’sservicelife.Thematerialsusedforrepairsshouldbeofhighquality.Important parameters for patching materials include low permeability, high bond strength,resistancetofreezethaw,andstrengththatisequaltoorsomewhatgreaterthantheelement.Recentstudieshavebeencompletedoncommonpatchingmaterialsthatincludedteststoverifytheseparameters [5]. This studycanbeused for the selectionofproperpatchingmaterials.Some ownersmaintain approved product lists, and some fabricators alsomaintain approvedproductlists.Ifpreviousapprovedbytheowner,thesematerialscanbeusedfortherepairs.

Voidsdiscoveredfollowingdetensioningorspallscausedbyhandling,transport,anderectionofbeams are, in almost all situations, repairable. The methods and materials used for repair,however, must be carefully considered to ensure the durability of the finished product inservice. The strain compatibility of the repair material with adjacent concrete must beconsidered from the time of repair through full service loading. The owner/engineer mustevaluatethedurability,aswellaslongevity,oftherepairfromthestandpointofpotentialfuturerepairs to a beam incorporated into the completed bridge and must consider methods topreventpatcheslocatedovertrafficfrombecomingdislodged.

Inmanyinstances,therepairofaspallissimplycosmetic(ratherthanrestorationofstrengthorprotection against corrosion of the prestressing or mild steel reinforcement). Considerationshouldbegiventonotrequiringrepairofaspallwhentherepairwillnotenhancestrengthordurabilityandislocatedinanareathatwillbeencasedbyaconcretepour,orwillnotbereadilyexposedtoview.

EssentialIssuestoBeConsideredInEngineeringEvaluationConditionofcracksunderfullserviceload:

1. Ingeneral,thepreferredconditionisthatatservice-levelstresses,precast,prestressedconcretebeamswillnothaveopencracks.This isespeciallytrueforbottomflangesofbeamsinpositivemomentregions.Therefore,anappropriateevaluationofanycrackinthebottomofthebeamwouldconsider,atservicelevel,thatstressesinthevicinityofacrackdonotexceed6√f’canywherealongthelengthofthecrack.

2. Transversecracksoriginatinginthetopofbeamsthatcloseupondetensioningoruponplacementof a composite slab shouldnotbeof concern.Open cracks in a top flangethatservesastheridingsurfacethatareobservedafterdetensioninganduponstorageontemporarysupportsattheirintendedbearinglocationsshouldbeevaluated.

3. Criteriaregardingcracksize,asitrelatestoenvironmentalconditions,arefoundinACICommittee Report ACI 224, "Control of Cracking in Concrete Structures." For beamsused in continuous span applications, negative bending capacity is based on crackedsectionanalysis,bothatserviceandstrengthlevels.Therefore,acrackthroughtheslaband portions of the beam depth are expected. At service level, the crack in the topflangecanbeexpectedtobeintherangeof0.008in.to0.01inches

10

The AASHTO LRFD Bridge Design Specifications contains provisions for control ofcracking[6].Theseprovisionsarebasedonanassumedcrackwidthof0.017inchesforelementsexposedtonormalconditionsand0.013inchesforelementsexposedtomoresevere conditions such as bridge decks. These criteria should be considered whendecidingwhethercracksneedtoberepaired.

AllowableStressesandStrength:

1. Allowable stresses in the repair and concrete bonded to the repair should not beexceeded at service loads. Allowable stresses in the repair material should becompatible or exceed the design stresses computed for the concrete in the originalbeam fabrication. Preloading themember prior tomaking repairs of a void detectedafter detensioning may be necessary if deemed essential to reducing undesirablestressesintherepair.

2. Allowable stressesat strand release shouldnotbeexceeded, considering the reducedsectioncausedbyavoid.

3. Flexuralandshearstrengthmustbeadequatenearbeamends,consideringthelackoffullydevelopedprestressingstrandswhencrackscrossstrandsorvoidsexposestrandswithintheirtransferlength.

4. Bearing stresses must remain within limits at service loads. Consider any reducedbearingareaabovethebearingdeviceduetoavoidinthebeamatitsbearing.

Conditionofthecrackunderdeadloadofgirderalone:

1. If thecrack isatthetopofagirderwhosetopflange istobetheridingsurfaceand isexposedtotensilestresses,itshouldbeinjectedorgravityfilledtopreventintrusionofwater, since the crack may remain open. Check stresses if the section is changedsignificantlybythedepthofcracking.

Conditionofthecrackunderdeadloadofgirderplusdeckslab:

1. Ifthecrackisatthetopofthegirderandisexposedtotensilestressesunderthedeadloadweightofthebeamplusslab, itshouldbe injectedtoprevent intrusionofwater,sincethecrackmayremainopen.Checkstresses if thesection ischangedsignificantlybythedepthofcracking.

2. Inmost cases, the crackwill go into compressionwith theweightof thedeckandnorepairwillberequired,unlessrequiredbyotherconditions.

3. An evaluation of the effects of other incidental issuesmay be required, including theeffects that cracking may have on the deck forming system and post-tensioninganchorages.

Note: Full development of exposedmild steel reinforcement can be restored by a properlyinstalledrepairprocedure.Ifthestrandhaslostsomeorallofitsprestressduetoacrackorvoidneartheend,however,itcannotberestoredatthatlocation.Transfermustoccurbeyondthelocation of the void. On the other hand, exposed strand beyond the transfer length can beassumedtohavefullprestressasthoughitwereneverexposed.

11

RepairableNon-conformancesThestandard repairprocedurescontainedherein include recommended repair criteria for thevariousnon-conformancesthataretypicallyencounteredduringthenormalfabricationprocess.Precastconcreteunitsthatcontainminordefectscausedbymanufactureormishandlingshouldbe repairedat themanufacturingsite. Inaddition,units thatcontainminordefectscausedbymishandlingduringshipmentorinstallationshouldberepairedattheprojectsite.

Non-RepairableNon-conformancesNon-repairablenon-conformancesmaybegroundsforrejectionoftheelement.Rejectionofaprecastelementshouldbeconsideredunderthefollowingconditions:

1. When thenon-conformances indicate a significant lackof conformancewith standardpractices and procedures. This includes elements having a significant number ofrepairable defects indicative of a lack of process management such as properconsolidationofconcreteandinadequatehandlingandstorage.

2. Amajordefectthataffectsthestructuralintegrityordurabilityoftheunit.Thistypeofdefectshouldbethoroughlyevaluatedbyallpartiesthroughanon-conformancereportorsimilarprocess.

Iftheproducerfollowsnormalproceduresandtheelementstillpresentsmanydefects,thenthedesignshouldbereviewedandadesignchangemaybeinorder.Forexample,abeamwithhighreleasetensilestressesmaybemorepronetocracking.

12

Section2:TroubleshootingGuideSection2.1:PrestressedElements

TS#1:TransverseCracksOriginatingatTopsofBeams TS#2:VerticalandDiagonalCracksatBottomofBeams TS#3:VerticalThroughCracksinBeams TS#4:HorizontalEndCracksinWebsandFlanges TS#5:BottomFlangeCracksatBeamEnds TS#6:CornerSpallsorCornerCracks TS#7:PartiallyCrackedTopFlanges TS#8:RandomHoneycombingandVoids TS#9:RandomTopFlangeCracks TS#10:ShortProjectedStrandorReinforcing,MissingProjectedStrandorReinforcing TS#11:CracksandHoneycombinginPrecast,PartialDepthDeckPanels TS#12:PartiallyCrackedTopFlanges–NEXTBeams

13

14

TS#1:TROUBLESHOOTINGFORTRANSVERSECRACKSORIGINATINGATTOPSOFBEAMS

Description: Thesecracksare typicallyperpendicular to the longitudinalaxisof thebeamandextendacrossthetopofthemember,usuallyvisibleonbothverticalfaces,butdonotextendtothe bottom prestress strands.

CAUSESA.Excessivetopfibertension

1. Releasestressesinexcessofmodulusofruptureofconcreteatrelease

2. Inadequatetopreinforcement3. Incorrectplacementoftop

reinforcement4. Lowreleasestrength5. Lackofstranddebondingatbeamends

orinsufficientnumberofdrapedstrands6. Improperlocationofliftingordunnage

points7. Prestressupliftforceatmid-span

hold-downpointsexceedstheweightofthebeamorexceedsthebeam’stopfibertensilecapacity

B. Shrinkage

1. Shrinkageofbeamconcretepriortoorduringcuring

2. Contractionofbeampriortoprestressforcerelease

3. Contractionofexposedstrandinunusedportionofthebed

C. FormExpansionwithTemperatureRiseD. ExcessiveSidetension

DueToLateralDisplacementDuringMovement

PREVENTION

A. ReduceTopFiberTension1. Review/modifydesigntoreducetop

tensionatrelease2. Provideadequatetensilereinforcement

tocontrolcracksoraddtopprestressing.Thisoptionmayincludelightlytensionedstrand(5000psi+).

3. Improveinspectionpriortoconcreteplacement

4. Increasereleasestrength5. Reduceeccentricityatbeamendsby

debondingordrapingstrandpattern,addstrandsattopsofbeamsormodifystrandpatterntoreduceeccentricity

6. Adjustliftingordunnagepoints7. Limitupliftforceathold-downpointsto

75percentofmemberweight

B. ImproveProductionMethods1. MinimizeShrinkage

b. Applycoversrapidlyand/ormistspraywithwater

c. Adjustconcretemixbyreducingcement,addingpozzolansorchangingaggregategradation

d. Provideuniformheatandhumidity

2. Detensionascoversareremovedandpreventrapidcool-downofthebeam

3. Preventexposedstrandfromcoolingdifferentiallywithrespecttothebeam

C. LengthenSetTime-InAccordancewithASTMC4031. Minimizetemperaturedifferential

betweenbeam,exposedstrand,andbed

15

2. Detensionascoversareremovedanddonotallowsectiontocoolrapidly

D. ProvideLateralBracingwith

StrongbacksTS#1:TROUBLESHOOTINGFORTRANSVERSECRACKSORIGINATINGATTOPSOFBEAMS

Description:Thesecracksaretypicallyperpendiculartothelongitudinalaxisofthebeamandextendacrossthetopofthemember,usuallyvisibleonbothverticalfaces,butdonotextendtothebottomprestressstrands.

ENGINEERINGEFFECTS 1. Cracksthatcloseupondetensioningofthe

beam,orthatwillclosewhenthebeamisplaceduponitsdesignatedbearingareas,orcanbeexpectedtoclosewhenthecompositeslabispoured,neednotberepairedforsimplebeamapplications.Forbeamsmadecontinuousforcompositedeadandliveloads,calculationsmayberequiredtodeterminetheneedforrepair.Ifstressesunderserviceloadsdonotexceed3.0√f’c,itmaybepresumedthatthebeamwillbehaveasanun-crackedsection,inwhichcasenorepairsarenecessary.Ifthestressesexceed3.0√f’c,thebeamshouldberepairedbyepoxyinjection.

2. Forcracksthatdonotcloseafter

detensioning,anassessmentoftheneedtorepairbasedoncontinuityconsiderationsaswellasenvironmentalexposurewillberequired.Inthelatterregard,ACICommittee224report“ControlofCrackinginConcreteStructures”statesthattolerablecrackwidthsare0.006-in.forconcreteexposedtoseawaterspraywithwettinganddrying,0.007-in.forconcreteexposedtode-icingchemicals,and0.012-in.forconcreteexposedtohumidity.

REPAIRCONSIDERATIONSBeforeDetensioning.Norepairsarerecommendeduntilafterdetensioning,ascracksmayclose.AfterDetensioning1. Closedcracks–Thedecisiontorepairornot

repairshouldbemadeinconsiderationoftheEngineeringEffects.

2. Cracksover0.006in.-Ifthedecisionis

madethatrepairsarewarranted,thecracksshouldbeepoxyinjectedinaccordancewithStandardRepairProcedure#10.

3. Thesurfaceofcracksnarrowerthan0.006-

inchesshouldbesealed.SeeStandardRepairProcedure#14.

16

17

TS#2:TROUBLESHOOTINGVERTICALANDDIAGONALCRACKSATBOTTOMOFBEAMSDescription: Thiscrackstartsatthebottomofthememberandextendsupward.Inseverecases,crack

willextenddiagonallytowardthemid-height(neutralaxis)ofthebeam.

CAUSE

A. Bondofstrands1. Strandcontamination2. Incorrectplacementofdebonding

shields3. Insufficientvibrationofconcrete4. Excessivedebondingterminationatone

locationB. ShrinkageC. DetensioningProcedure

1. Lowreleasestrength2. Improperdetensioning

sequence/procedures3. Failuretoreleasehold-downmechanism

priortoreleaseofhorizontalstrandsD. Formwork

1. Indentationsorjointoffsetsinforms2. Concretebindingtoforms3. Bottomplatesatbeamendsanchoredor

hungupatbottom(soffit)offormE. IncorrectPrestressForce

1. Inadequateprestressstrandindesign2. Under-estimateofprestresslosses3. Under–tensioningofstrand4. Incorrectnumberofstrandinbed

PREVENTIONA. Ensureagainstunintendedslip

1. Inspectstrandforcleanlinessandabsenceoflubricantsafterstressingstrand

2. Verifypropershieldinginstallation3. Useinternalandexternalvibrationin

congestedendsofbeams4. Staggerdebondingterminations

B. ImproveProductionMethods1. Applycoversrapidlyafterconcrete

pours2. Detensionascoversareremoved3. Preventexposedstrandfromcooling

differentiallywithrespecttothebeam

4. Adjustconcretemixbyreducingcement,addingpozzolansorchangingaggregategradation

5. Provideuniformheatandhumidity

C. Useproperdetensioningprocedure1. Ensureproperconcretestrength

priortorelease2. Keepprestressedforcesbalanced

whiledetensioning,usinganestablishedprocedure

3. Ensurehold-downsarereleasedpriortodetensioningstrandandarenotbindingonthesoffit

D. Inspectformconditionpriortoplacing

Concrete1. Ensuresmoothformalignment2. Oilformsthoroughly3. Ensureanybottomplateswillnot

bindonsoffit

E. ApplyCorrectPrestressForce1. Checkdesigncalculations2. Recomputelosses3. Comparemeasuredelongationof

strandwithcomputedelongation4. Checkshopdrawings

18

5. Checkcamberofbeamversescalculatedcamber

TS#2:TROUBLESHOOTINGVERTICALANDDIAGONALCRACKSATBOTTOMOFBEAMS

Description: Thiscrackstartsatthebottomofthememberandextendsupward.Inseverecases,crackwillextenddiagonallytowardthemid-height(neutralaxis)ofthebeam.

ENGINEERINGEFFECTS1. Forverticalcracksthatinterceptbondedor

debondedstrandwithintheirrespectivetransferlengths,itisrecommendedthattheengineerre-computethemomentandshearcapacitybasedontransferinitiatingatthepointofthecrack.Ifthere-computedcapacitiesareacceptablethebeamcanberepaired.Thesecracksshouldbeinjected.

2. Verticalcracksthatinterceptbondedordebondedstrandbeyondtheirrespectivetransferlengthsandclosetoawidthlessthan0.006-in.afterdetensioning,neednore-evaluation.Cracks0.006-in.orgreaterinwidthshouldbereferredtotheengineerforevaluation,toaffirmadequatedesign.

3. Verticalcracksatanylocationonthebeamthatdonotinterceptstrandneednoevaluationbytheengineer.

4. Diagonalcracksofanysize,atanylocation,requireevaluationbytheengineer,todeterminewhetherthesheardesignforthebeamisadequateortheaccidentalloadingcausingthecrackwillnotbeduplicatedinservice.

REPAIRCONSIDERATIONS1. Itisrecommendedthatcracksnotbe

repairedpriortodetensioningasrepairswillmaskthecauseandseriousnessofthecrack.

2. Allcrackslessthan0.006-in.inwidth,afterdetensioninganddeemedacceptable,shouldbesealed.SeeStandardRepairProcedure#14.Ifthesecracksarewithinthetransferzone,anepoxyinjectionrepairshouldbeconsidered(seebelow).

3. Allcracks0.006-in.orgreaterinwidth,afterdetensioninganddeemedacceptable,shouldberepairedbyepoxyinjectioninaccordancewithStandardRepairProcedure#10.

19

20

TS#3:TROUBLESHOOTINGVERTICALTHROUGHCRACKSINBEAMS

Description:Thesecrackscandevelopinbeamsduringthecuringprocessorcool-downperiodpriortodetensioningofstrand.Thisproblemismorecommontolongbeamsmanufacturedwithhigherstrengthconcrete.

CAUSEA.Shrinkage1. Shrinkageofthebeampriorto

detensioningB.TemperatureEffects1. Contractionofexposedstrandinunused

portionofbed2. Contractionofbeamduetocoolingprior

totransferofprestress3. Unevendistributionofheat

C.Production/Formwork1. Indentationsorjointoffsetsinforms2. Concretebindingtoforms3. Bottomplateatendofmemberanchored

orrestrainedinform

PREVENTIONA.Reviewormodifythemixormodifycuring

methodstoreduceshrinkage1. Considerchangetoalternatemix(seenote)

2. ApplycuringcoversrapidlyB.ControlTemperatureDuringProduction

1. Minimizetemperaturedifferentialbetweenbeam,exposedstrand,andbed

2. Detensionascoversareremovedanddonotallowsectiontocoolrapidly

3. Provideuniformheatandhumidityduringcuring

C.Improveproductionmethods

1. Keepformsingoodrepair;fabricateformswitheven,smoothjoints

2. Keepformscleanandproperlyoiled3. Releaserestraintofallplatesbeforedetensioning

Note:Modificationstomixdesignsmaynotbe

possibleincertainsituationsduetoownerpre-qualificationrequirementsformixes.

Reference:Zia,Paul,andCaner,Alp,“CrackinginLong-SpanPrestressedConcreteAASHTOGirdersDuringProduction”,CenterforTransportationEngineeringStudies,NorthCarolinaStateUniversity,Raleigh,N.C.

21

TS#3:TROUBLESHOOTINGVERTICALTHROUGHCRACKSINBEAMS

Description:Thesecrackscandevelopinbeamsduringthecuringprocessorcool-downperiodpriortodetensioningofstrand.Thisproblemismorecommontolongbeamsmanufacturedwithhigherstrengthconcrete.

ENGINEERINGEFFECTS1. Forcracksfallingwithinthetransferlengthof

bondedordebondedstrand,itisrecommendedthattheengineerre-computethemomentandshearcapacitybasedontransferinitiatingatthepointofthecrack.Ifthere-computedcapacitiesareacceptablethebeamcanberepaired.Thesecracksshouldbeinjected.

2. Forcracksfallingbeyondthetransferlengthofbondedordebondedstrandthathaveawidthof0.006inchorless,afterdetensioning,noreevaluationisneeded.Cracksgreaterthan0.006inchshouldbereferredtotheengineerforevaluation.

3. Fulldepthcracksthatcloseafterdetensioningtoawidthoflessthan0.006-in.,orare0.006-in.orgreaterandrepairedmeettheconstitutiverulesofthemodifiedcompressionfieldtheoryforshearcapacity.Thesubjecttheory,asabasicgiven,presumesafulldepthcrackalongtheinclinedplaneofthetadegrees.Underfulldesignloadifthebottomflangeatthepre-existingcrackgoesintotension,thecrackwillopenalongitsverticalpathuntiltheneutralaxisisreached,atwhichpointthecrackwillturnandextendalongtheinclinedplane,theta.Asthecompressionstrutcantransmitstressacrosstheverticalportionofthecrack,theconstitutiverulesarenotcompromised

REPAIRCONSIDERATIONS1. Itisrecommendedthatcracksnotbe

repairedpriortodetensioningasrepairswillmaskthecauseandseriousnessofthecrack.

2. Allcrackslessthan0.006-in.inwidth,afterdetensioninganddeemedacceptable,shouldbesealed.SeeRepairProcedure#14.Ifthesecracksarewithinthetransferzone,anepoxyinjectionrepairshouldbeconsidered(seebelow).

3. Allcracks0.006-in.inwidth,afterdetensioninganddeemedacceptable,shouldberepairedbyepoxyinjectioninaccordancewithStandardRepairProcedure#10.

22

TS#4:TROUBLESHOOTINGHORIZONTALENDCRACKSINWEBSANDFLANGES

Description: Thiscrackusuallybeginsattheendofthebeamandextendsacrosstheendofthebeamandisvisibleonbothsides.

CAUSEA. Detensioning

1. Improperproceduresfordetensioningstrands

2. ImproperdetensioningsequenceB. Design

1. Lowreleasestrengthspecified2. Inadequateendverticalreinforcing3. Excessiveprestressforceor

concentrationofforce4. Excessivenumberofdebondedstrands

inthebottomplaneand/orlackofconfiningstirrups

5. Excessiveverticalforcefromdeflectedstrands

C. Production

1. Concretebindinginforms2. Bottomplates,sleevesorinsertsatend

ofbeam3. Shrinkageandcuring4. Improperremovalofheaderorstrand

caughtinheader5. Settlementofwetconcretebelowa

concentrationofstrandormildreinforcingnearthetopatbeamend

6. Forboxbeams,delayedwebpourscausingacoldjoint

PREVENTIONA. ProperReleaseProcedure

1. Heatstrandtoallowslowelongation(annealing)andavoidsuddenrelease

2. Keepprestressforcesbalancedusingapre-stablishedprocedure(seeNote)

B. ImproveDesign

1. Establishadequatereleasestrength2. Useadequateanchoragezoneend

reinforcementtocontrolwidthandlengthofcracks

3. Properlyspaceanddistributestrandatbeamends

4. Debondingstrandsforashortdistanceiseffectiveinreducingstressconcentrations.Debondingofanentirerowofstrandordebondingtheouterstrandinalayerarenotrecommended.Provideconfinementreinforcementnearbeamends

5. Fanoutdeflectedstrandsorcombinedebondinganddeflectingstrand

C. ImproveProductionTechnique

1. Keepformswelloiled2. Ensureformswillnotinterferewith

hardwareifformsexpandorduringdetensioning

3. Provideuniformheatandhumidityduringcuring

4. Separateheaderfromformsbeforelifting

5. Improvevibrationtechniques6. Pourwebspriortosetofbottomslabof

boxbeamsNote:Balancingofprestressforceiskeyto

minimizingthepotentialforhorizontalcracks.See“ReleaseMethodologyofPrestressStrands”,KannelJ.,FrenchC.andStolurski,H.,PCIJournalVol.42,No.1,Jan-Feb.1997,pp.42-55

23

TS#4:TROUBLESHOOTINGHORIZONTALENDCRACKSINWEBSANDFLANGES

Description: Thiscrackusuallybeginsattheendofthebeamandextendsacrosstheendofthebeamandisvisibleonbothsides.

ENGINEERINGEFFECTS1. Cracksnotinterceptingstrandarenotof

structuralconsequence,providedtheareaofverticalshearreinforcementinthewebsmeetshorizontalshearrequirements.Afterinstallationofthebeams,thecrackswouldnotbeexpectedtogrow,givenadequatereinforcementagainsthorizontalshear,sincethedeadloadweightoftheslabandotherdeadloadswillinduceverticalcompressioninthebeamsends.

2. Forcracksthatinterceptorareco-linearwithstrands,theshearandmomentcapacitywillrequirere-computationduetoachangeinlocationoftransferlengthofaffectedstrands.

3. Cracksinbeamendsunderexpansionjoints,shouldbeconsideredforepoxyinjectiontoavoidfuturedeteriorationfromwaterandsaltintrusion.Cracksinboxbeams,inside-by-side(butted)configurationsshouldbeepoxyinjectedinanycaseduetopotentialleakagethroughgroutedjoints.

4. Indecidingwhethertoinjectcracksorleavethemunfilled,ACICommittee224report“ControlofCrackinginConcreteStructures”statesthattolerablecrackwidthsare0.006-in.forconcreteexposedtoseawaterspraywithwettinganddrying,0.007-in.forconcretesubjecttode-icingchemicalsand0.012-in.forconcreteexposedtohumidity.

REPAIRCONSIDERATIONS

1. NorepairstobeamsusedincompositeconstructioninaccordancewiththediscussioninENGINEERINGEFFECTS1.

2. ForcracksdiscussedinENGINEERINGEFFECTS2:a. Cracksthathavebeenverifiedby

theownertonothavediminishedthebeamcapacitybelowacceptablelevelsshouldbeinjected,inaccordancewithStandardRepairProcedure#10.

b. Beamsverifiedbytheengineertohavecapacityreducedtounacceptablelevelswillberejected.

3. Durabilityconcerns,discussedinENGINEERINGEFFECTS3and4mayfavorepoxyinjection,inaccordancewithStandardRepairProcedure#10.Thesurfaceofcracksnarrowerthan0.006-inchesshouldbesealed.SeeRepairProcedure#14.

24

TS#5:TROUBLESHOOTINGBOTTOMFLANGECRACKSATBEAMENDSDescription: Thecrackislocatedattheendofthebeamandgenerallyrunsparalleltothelongitudinal

axis.CAUSEA. Production

1. Bindingintheformsduringstripping2. Indentationintheforms3. Improperdetensioningsequence

BReinforcement

1. Incorrectplacementoromissionofconfiningreinforcement

2. Reinforcementimproperlydetailedorfabricated

3. Debondingproblem4. Contaminatedstrand

C. Detensioning

1. Localizeddifferentialstrainsandstressesbetweenthewebandflangeduringdetensioning

D. Handling

1. Non-uniformbearingondunnageorimpactwhilebeingloweredondunnage

PREVENTIONA. ImproveProduction

1. Keepformswell-oiledandclean2. Keepformsingoodrepair3. Keepforcesbalancedduring

detensioningB. AttentiontoReinforcingDetails

1. Verifycorrectplacementofreinforcement

2. Scrutinizedrawingsandfabricatedbarstobeused

3. Allowforswelling(HoyerEffect)ofdetensionedstrandthathavebeendebondedbyprovidingconfinementreinforcingorrelocatingdebondedstrandsawayfromedgesoftheflange.

4. Inspectstrandforcontaminationandoilresiduefrommanufacturing

C. Detensioning

1. Heatstrandtoallowslowelongation(annealing)tominimizeshockofdetensioning

D.Handling

1. Ensureuniformbearingandavoidimpactswhenhandlingbeams

25

TS#5:TROUBLESHOOTINGBOTTOMFLANGECRACKSATBEAMENDS

Description: Thecrackislocatedattheendofthebeamandgenerallyrunsparalleltothelongitudinalaxis.

ENGINEERINGEFFECTS1. Cracksco-linearwithstrandsaffectthe

unbondedlengthanditwillbenecessarytorecomputetheshearandmomentcapacitybasedontherevisedtransferand/ordevelopmentlengthlocationforthestrands.Weakaxisbendingmayneedchecking.

2. Inanyevent,thesecracksshouldberepairedtoensuretheintegrityofthebearingareaandtopreventwaterandsaltintrusionatexpansiondevicesorthroughgroutedshearkeysofside-by-side(butted)boxbeams.


1. AllbottomflangecracksshouldbeepoxyinjectedinaccordancewithStandardRepairProcedure#10

2. INthecaseofstrandinvolvement,theengineershouldbenotifiedtoassessconditionspriortorepairs.

26

TS#6:TROUBLESHOOTINGCORNERSPALLSORCORNERCRACKS

Description: Thesespallsandcrackscanbefoundatanyedgeorcornerofflangesalongthebeam

CAUSEA. ImproperHandling

1. Impactingedges2. Unevendunnage

B. Production

1. Bindinginformsduringstripping2. Indentationinforms3. Insertshangingupinforms4. Soleplatesnotflushwithsoffitof

forms5. Impropershieldingofstrands6. Thermalexpansionofformspriorto

concretesetting7. Improperbulkheadremoval8. Bleedingofconcreteunderheader

C. ReleaseProcedures

1. Improperdetensioningsequence2. Bindinginformsduringdetensioning3. Draggingofbottomflangeendinduced

bycamberingandshorteningatdetensioning

4. Impactandburstingforcesfromdetensionedstrand

D. Design

1. Inadequateedgereinforcement

PREVENTIONA. CareinHandling

1. Ensureadequateroomfortransportofbeams

2. ProvideuniformdunnageB. ImproveProductionMethods

1. Keepformscleanandwelloiled2. Keepformsingoodconditionand

ensureallseamsaremortartight3. Ensureinsertsarefreeduringstripping4. Ensuresoleplatesareflushwithsoffit

priortoconcretepours5. Shieldinginthebottomrowofstrands

shouldbeminimizedandshieldingofstrandsadjacenttotheedgesofflangesshouldbeavoided

6. Ensureconcretesetpriortostartingcuring

7. Keepbulkheadsingoodconditionandwell-oiledtoavoidtheneedtoprythemloose

8. Providemortar-tightheader

C. ProperReleaseProcedures1. Keepprestressforcesbalancedduring

detensioning2. Providesufficientclearancebetween

formsandbeamduringdetensioning3. Provideskidplates,radii,bevelsor

compressiblematerialforthebottomedgeofflanges

4. Heatstrandsufficientlytoslowlyelongate(annealing)toavoidimpactandtomitigateswellingofstrand(HoyerEffect)atrelease

5. Ensureallstrandsarecompletelyseveredpriortoremovalfromforms

D. Design1. Provideproperreinforcementasclose

toedgesasclearancerequirementsallow

27

TS#6:TROUBLESHOOTINGCORNERSPALLSORCORNERCRACKS

Description: Thesespallsandcrackscanbefoundatanyedgeorcornerofflangesalongthebeam

ENGINEERINGEFFECTS1. Cornerspallsintopflangesusedasthe

ridingsurfaceofthecompletedbridgerequirerepairtoensuresufficientliveloadcapacityanddurability

2. Cornerspallsinbearingareasofbeamsshouldberepairedtoensureproperbearingsaswellastoprotectstrandsfromwaterandsaltintrusionwhenbeamendsareadjacenttoexpansionjoints.

3. Cornerspallsinthebottomflangethatmaysignificantlyreduceprotectionfromsaltandwatersprayfromtrafficunderneathorleakinggroutedjointsfromabove,suchasside-by-sideboxesanddeckbulb-tees,shouldberepaired.

4. Ifstrandsareexposed,theengineeringeffectshouldbereviewedbytheEngineer.

5. Topflangeedgesincorporatedintoslabpoursneednotberepaired

REPAIRCONSIDERATIONS1. Wherecornerspallsaredeemedinneedof

repair,therepairsshouldbemadeinaccordancewithStandardRepairProcedures#3or#4

2. Cornerspallsonedgestobeincorporatedintocompositeslaborenddiaphragmsmaynotneedrepair

3. Minorspallsthatdonotcompromiseprotectionfromwater,saltsprayorhumidity,orarenotexposedtodirectviewneednotberepaired

28

TS#7:TROUBLESHOOTINGPARTIALLYCRACKEDTOPFLANGES

Description: Thecrackwidthisusuallyvisibleandexhibitsacleanbreakline.

CAUSEA. Handling

1. ImpactingedgesB. Production

1. Bindinginformsduringstripping2. Placementofconcreteinexcessively

hotforms3. Thermalexpansionofformspriorto

concretesettingorcontractionduringcool-down

C. ReleaseProcedures

1. Improperdetensioningsequence2. Strandsnotfreefrombulkhead

D. StrandPlacement

1. Concentrationofprestressingforcesattheedgesoftopflanges

PREVENTION

A. ProperHandling1. Ensureadequateroomfortransportof

beamsB. ImproveProductionMethods

1. Keepformscleanandwelloiled.Keepformsingoodrepair,freeofdentsanddimples

2. Ensureformsarecooledtoanappropriatetemperaturepriortoplacingconcrete

3. Regulateheatduringcuringandcool-downuniformly

C. ProperReleaseProcedures

1. Keepprestressforcesbalancedduringdetensioning

2. Ensureanytopstrandsarecompletelyseveredpriortoremovalfromforms

3. Providesufficientclearancebetweenformsandbeamsduringdetensioning

D. ProperDesignDetailing

1. Avoidplacementofprestressnearedgesoftopflange,orifthisisunavoidable,addtransversereinforcementtoflanges

29

TS#7:TROUBLESHOOTINGPARTIALLYCRACKEDTOPFLANGES

Description: Thecrackwidthisusuallyvisibleandexhibitsacleanbreakline.

ENGINEERINGEFFECTS

1. Forbeamswhosetopflangeistobeusedas

theridingsurfaceofthecompletedbridge,cracksinthetopflangecanaffectdurabilityandliveloadcapacity,ifnotrepaired

2. Forbeamstoreceiveacast-in-placeslab,repairsmaynotbewarranted

REPAIRCONSIDERATION1. Whenthetopflangeistobetheriding

surface,andconcreteisdisplaced,fracturedorloose,useStandardRepairProcedure#6.IfthecrackiscleanandnoconcreteisdisplaceduseStandardRepairProcedures#10.

2. Whenthetopflangeistobeencasedinacast-in-placeslab,andconcreteintheflangeisdisplaced,theengineershouldbenotifiedtodetermineiftheflangeshouldberepairedusingStandardRepairProcedures#6orifthedisplacedconcretecanbeleftandencasedintheslab.Ifthecrackiscleanandnoconcreteisdisplaced,norepairsarewarranted.

30

TS#8:TROUBLESHOOTINGRANDOMHONEYCOMBINGANDVOIDSDescription: Missingvolumeofcementpastefromaroundaggregateorvoidscontainingneitherpaste

noraggregate,inflangesandwebs.

CAUSEA. Production

1. Inadequatevibration2. Improperplacementofconcrete3. Shifted/misplacedrebarcage

B. ConcreteMixDesign

1. Mixtoostiff2. Earlysetinplasticizedconcrete3. Delayedplacementofconcrete4. Flashsetofconcreteinforms

C. DesignDetails

1. Congestedreinforcement

PREVENTIONA. ImprovedProductionProcedures

1. Providethoroughinternaland,wherewarranted,externalvibration

2. Startplacementawayfrombulkheadsandusevibrationtocausetheconcretetoflowtowardbulkheads

3. Verifylocationofandanchorreinforcement

B. AdjustMixDesign

1. Considerchangetoalternatemix(seenote)

2. Improvedeliverytimeoftheconcrete3. Coolformspriortoconcrete

placementC. ImproveDetails

1. Reducereinforcementcongestiontotheextentpossible

2. Provideclearspacingbetweenreinforcementlargerthan1½timesthemaximumaggregatesize

Note:Modificationstomixdesignsmaynotbe

possibleincertainsituationsduetoownerpre-qualificationrequirementsformixes.

31

TS#8:TROUBLESHOOTINGRANDOMHONEYCOMBINGANDVOIDS

Description: Missingvolumeofcementpastefromaroundaggregateorvoidscontainingneitherpaste

noraggregate,inflangesandwebs.ENGINEERINGEFFECTS1. Honeycombingandvoidsinbearingareas

notonlyaffectthestrengthanddurabilityofthebearingbut,themomentcapacityifbondonthestrandisimpacted.Undermodifiedcompressionfieldtheory,lossofbondofstrandcanalsoaffectshearcapacity.Theseareasmustberepaired.Honeycombingandvoidsinotherareasofthebottomflangecanaffectmomentcapacity,butmorelikely,onlydurability.

2. Honeycombingandvoidsinwebsaffectshearcapacityandmustberepaired.

3. Honeycombingandvoidsintopflangesthatwillbetheridingsurfaceofthebridgeaffectbothmomentcapacityanddurability,requiringrepair.Wherethetopflangeistobeencasedinacast-in-placeslab,thehoneycombingandvoidsmaysignificantlyaffectthenon-compositestrengthbutnotdurability.


REPAIRCONSIDERATIONS1. ForconditionsdiscussedinEngineering

Effects1,repairusingStandardRepairProcedures#1or#2,asappropriate.

2. ForconditionsdiscussedinEngineeringEffects2,repairusingStandardRepairProcedures#5or#9,asappropriate.

3. ForconditionsdiscussedinEngineeringEffects3,ifrepairsarerequired,useStandardRepairProcedures#6or#9,asappropriate.

32

TS#9TROUBLESHOOTINGRANDOMTOPFLANGECRACKSDescription: Thesecracksaregenerallyorientedlongitudinallyandareshallowindepth,occurringina

randompattern,oftenparallelwithreinforcement.CAUSEA. Shrinkage

1. Excessbleedwateratthetopflangesurface

2. Rapidmoisturelosspriortocuring3. Excessivecuringtemperature4. Delayedstartofcuring

B. ConcretePlacement

1. Settlementofconcretearoundtopreinforcement(subsidence)

2. InsufficientVibration

PREVENTIONA. PreventShrinkage

1. Reducewaterinmixandoravoidover-workingsurfacefinish

2. Useretardantadmixturescoverbeamscompletelyandassoonaspossible(especiallyinwindy,hotanddryconditions).Ifnecessary,mist-sprayexposedtopflangesurface,withwater.

3. Reducecuringtemperature4. Determineproperpre-settimetosuit

curingoperations,usingASTMC403.Limitstartofcuringto2-3hours

B. ImprovePlacementMethods

1. Allowtimeforinitialsettlement,andre-vibrateconcrete

2. Ensurepropervibrationtoconsolidateconcrete

33

TS#9TROUBLESHOOTINGRANDOMTOPFLANGECRACKS

Description: Thesecracksaregenerallyorientedlongitudinallyandareshallowindepth,occurringina

randompattern,oftenparallelwithreinforcement.

ENGINEERINGEFFECTS1. Otherthanconcernfordurabilityfortop

flangesthatwillbecometheridingsurfaceofthecompletedbridge,therearenoconcerns.Thesecrackswillbecoveredbytheslabincompositeconstruction

REPAIRCONSIDERATIONS1. Wherethetopflangewillbetheriding

surface,sealwithalowviscosityepoxyormethylmethacrylateproduct.

2. Wherecompositeconstructionisused,norepairsareneeded.

34

TS#10TROUBLESHOOTINGSHORTPROJECTEDSTRANDORREINFORCING,MISSINGPROJECTEDSTRANDORREINFORCING

Description: Thistypeofdefectisusuallycausedbyimproperproductiondetailing.Itisusuallylimited

toprojectingstrandorreinforcingforcontinuityconnectionsorhorizontalshearreinforcing.

CAUSEA. Formwork

1. BulkheadshiftB. Reinforcement

1. Improperplacement2. Impropercutting3. Improperbending4. Incorrectfabricationdrawingordesign

drawing5. Shiftingduringcasting6. Improperhandling

PREVENTIONA. Formwork

1. CheckbulkheadlocationsandintegrityB. Reinforcement

1. Re-checkreinforcing/strandlocationspriortoconcreteplacement

2. Re-checkstrand/reinforcinglengthsbeforecutting

3. FollowCRSIrequirementsforminimumbendingradius

4. Re-checkfabricationanddesigndrawings

5. Placeadditionaltiesonreinforcement6. Reviewshophandlingpractices

35

TS#10TROUBLESHOOTINGSHORTPROJECTEDSTRANDORREINFORCING,MISSINGPROJECTEDSTRANDORREINFORCINGDescription: Thistypeofdefectisusuallycausedbyimproperproductiondetailing.Itisusuallylimited

toprojectingstrandorreinforcingforcontinuityconnectionsorhorizontalshearreinforcing.

ENGINEERINGEFFECTS1. Missingstirrupscanmateriallyaffectthe

horizontalshearcapacityaswellasverticalshearcapacity.Calculationsmayverifynosignificantreductioninshearcapacity.Ifso,repairmaynotbenecessary.

2. Missingprojectingstrandwillreducethepositivemomentrestraintcapacityattheinteriorsupportsofbeamsmadecontinuousforcompositedeadandliveloads.

3. Whereprojectedstrandaretobedevelopedwithincast-in-placediaphragms,toensureadequatelongitudinaltensiontiecapacityforbeamverticalsheardesignmaybecompromised.RefertoAASHTOLRFDArticle5.8.3.5.

Note1:Repairsshallnotbemadewithoutthedesigner’sapproval;thefollowingaregeneralguidelines:Note2:Ifacceptabletotheowner,asmallamountofconcretecanberemovedandthestrandcanberepairedasashortprojectingstrand


MissingProjectedStrandreplacedwithgroutedrebar(seeNote2)1. Thisprocedureshouldonlybeusedforrepairing

upto25%oftheprojectingstrand.2. Eachmissingstrandshallbereplacedbytwo#6

rebargroutedadjacenttothemissingelementwith24”ofembedment

3. Thegroutedrebarshallbeascloseaspracticaltothemissingelement.

4. SeeStandardRepairProcedure#12MissingProjectedRebar1. Thisprocedureshouldonlybeusedforrepairing

upto25%oftheprojectedreinforcingatbeamends.

2. EachmissingrebarshallbereplacedbyanequivalentsizedGrade60rebar.

3. Theembedmentshallbesufficienttodevelopafulllapsplicewiththeinternalreinforcingwheretensiontransferisrequired.

4. Theminimumembedmentforothersituationsshallbebasedonthechemicaladhesivemanufacturer’srecommendations.

5. SeeStandardRepairProcedure#12ShortProjectingRebar1. Useamechanicalcouplerthatisapprovedby

theOwner,installedasperthemanufacturer’srecommendations

2. SeeStandardRepairProcedure#11.ShortProjectingStrands1. Thisprocedurecanbeusedforanynumberof

shortprojectingstrandsperbeamthathassufficientstrandremainingthatistightlywoundinordertofollowthisrepairprocedure;ifthiscan’tbemet,treatasamissingstrand.Saw-cutstrandcleanlywithacutoffsawandinstallaself-seatingsplicechuckwithadditionalpieceofstrand.

2. SeeStandardRepairProcedure#11.

36

TS#11TROUBLESHOOTINGCRACKSANDHONEYCOMBINGINPRECAST,PARTIALDEPTH

DECKPANELSDescription:Longitudinal,transverseanddiagonalcracks,andhoneycombinginpanels.CAUSESA. Longitudinalcracksrunningco-linearto

strands1. Improperdetensioningprocedures2. Excessiveprestressingforce3. Inadequateendreinforcement

transversetostrandpattern4. Castingconcreteinhotforms5. Lowreleasestrengthofconcrete

B. Longitudinalcracksnotco-lineartostrand,

transversecracksordiagonalcracksinpanels1. Improperhandling(impact)2. Improperstorage3. Shrinkage4. Improperdetensioningprocedures5. Strandpatterneccentrictopanelmid-

depthC. RandomHoneycombing

1. Impropervibration

PREVENTIONA. Longitudinalcracksrunningco-linearto

strand1. Keepprestressingforcesbalanced

duringdetensioning.Heatstrandtoensureslowelongationofstrand(annealing)duringdetensioning.

2. Keeptheaverageprestressforceovertheendfaceofpanelsto750psi.

3. Providetransversemildreinforcingsteelaboveandbelowthestrandatpanelends.

4. Coolforms,headers,strandandmildreinforcing,thatcomesincontactwithwetconcrete,atorbelow90°F.

5. Increasereleasestrength.B. Longitudinalcracksnotco-lineartostrand,

transversecracksordiagonalcracksinpanels.1. Provideadequatedraftformoving

panels.Avoidimpacts2. Keepdunnageleveland,uniformly

spaced.Provideuniformbearingofpanelstransversetostrands.

3. Avoidrapidcooling,aftercuringhasstoppedanduntildetensioningiscomplete.

4. Keepprestressingforcesbalancedduringdetensioning.

5. Keepstrandplacementatmid-depth.C. RandomHoneycombing

1.Properlyvibrate

37

TS#11TROUBLESHOOTINGCRACKSANDHONEYCOMBINGINPRECAST,PARTIALDEPTH DECKPANELSDescription:Longitudinal,transverseanddiagonalcracks,andhoneycombinginpanels.ENGINEERINGEFFECTS1. Cracksco-linearwithstrand,either

extendingfromthetoporbottomfacetostrands,orthroughcracksareanindicatorofdebonding.Experiencehasshownthatevencracksthatarepartiallengthofstrandwillcontinuetogrowfulllengthofstrandovertime,evenafterepoxyinjection.Theownershouldbeconsultedwhenmorethan6percentofstrandhavesuchcracks.Twoconsecutivestrandhavingcracksshouldbecauseforrejection.

2. Longitudinalcracks,parallelbutnotco-lineartostrandareofnostructuralconsequence.

3. Transverseanddiagonalcracksthatcrossmorethan6percentofstrandrequireanassessmentbytheowner.Becauseoftherelativelyshortlengthofpanels,comparedtothetransferanddevelopmentlengthofthestrandsitislikelythatanycrackinterceptingstrandswillcausedebonding.

4. Honeycombingnotmorethanone-inchdeep,inthetoporbottomfaceofpanelsandnotofextensiveplanareaareofnostructuralconsequenceifrepaired.Honeycombingdeeperthanone-inchmaycompromisestrandbond.

REPAIRCONSIDERATIONS1. Cracksco-linearwithstrandandextending

fromonefacetothestrand,orthroughcracksco-linearwithstrandovermorethan12percentofstrandshouldberejected.

2. Longitudinalcracksparalleltobutnotco-linearwithstrandthatexceed0.007inchesinwidthshouldbeconsideredforepoxyinjectioninaccordancewithStandardRepairProcedure#10.

3. Transverseordiagonalcracksextendingovermorethan12percentofstrandshouldberejected.

4. Honeycombingnotexceedingone-inchindepthateitherface,ofanacceptableplanarea,shouldberepairedinaccordancewithStandardRepairProcedures#1,#2or#5.

38

TS#12TROUBLESHOOTINGPARTIALLYCRACKEDTOPFLANGES–NEXTBEAMSDescription: Crackrunningparalleltobeamcenterlinealonginsidefaceofstem.

Thiscrackisexpectedinobtusecornersofskewedbeamsadjacenttotheinteriorfaceofthestem,butcanoccurinanybeam.

CAUSE PREVENTION

A. Detensioning

1. Releasestressesbroughtonbyskeweffects.Unevenlift-offofbeamstemsbroughtonbyskew[8].

2. Releasestressesduetounevendetensioningsequencebetweenbeamstems.

3. Bindinginformsduringstripping

A. AdjustReinforcementanddetensioningsequence1. Verifythatadditionalreinforcingsteel

thatisshowninthecurrentPCINortheastrecommendedguidedetailsarebeingusedandinstalledproperly.Note:ThereinforcementdescribedabovewasaddedtothetypicaldetailsonOctober25,2012.

2. Releaseonestrandatatimealternatingfromstemtostem.

3. Keepformscleanandwelloiled.Keepformsingoodrepair,freeofdentsanddimples.

B. Shrinkage

1. Shrinkageoftopflangeconcreterestrictedbythefixed2stemform.

B. ModifyFabricationMethods1. Avoidrapidcooling,aftercuringhasstopped

anduntilbeamisremovedfromform.

39

TS#12TROUBLESHOOTINGPARTIALLYCRACKEDTOPFLANGES–NEXTBEAMS

Description Crackrunningparalleltobeamcenterlinealonginsidefaceofstem.

Thiscrackisexpectedinobtusecornersofskewedbeamsadjacenttotheinteriorfaceofthestem,butcanoccurinanybeam.

ENGINEERINGEFFECT REPAIRCONSIDERATIONS1. Forbeamsthatwillbetoppedwitha

compositeconcreteslab(NEXTF),therearenoconcerns.Thesecrackswillbecoveredbytheslabincompositeconstruction.

2. Forbeamswhosetopflangeistobeusedastheridingsurfaceofthecompletedbridge(NEXTD),cracksinthetopflangecanaffectdurability,ifnotrepaired.

1. Whereacompositeconcretedeckisembeddedinconcreteinthefinishedstructure(integralabutment),nostructuralrepairsareneeded.

2. NEXTF:Ifthecrackisexposedontheundersideofthefinishedstructureandthebridgeisinacorrosiveenvironment:• Crackslessthan0.006inchwideshouldbe

ignored(SeeNote).• Cracksgreaterthanorequalto0.006inch

wideandlessthan0.016inchwideshouldbesealedwithepoxypaste.SeeStandardRepairProcedure#14.

• Cracksgreaterthanorequalto0.016”wideshouldbesealedusingepoxyinjectionbythepressureinjectionmethod.SeeStandardRepairProcedure#10.

3. NEXTD:Wherethetopflangewillbetheridingsurfaceandthecrackwidthisgreaterthan0.006inches,thecrackatthetopsurfaceofthedeckcanbesealedwithalowviscosityepoxyormethylmethacrylateproduct.SeeStandardRepairProcedure14.

Note:TheAASHTOLRFDBridgeDesignSpecificationslimitscrackwidthsinClass2exposureconditions(bridgedecks)to0.0085inches(Article5.7.3.4).Thereforetheserecommendationsareconservative.

40

41

Section2.2:Non-PrestressedPrecastElements

TS#SS1:CornerSpallsTS#SS2:CracksTS#SS3:Honeycombing,Voids,PourLines,andMinorSurfaceImperfectionsTS#SS4:ShortProjectedRebarandMissingProjectedRebarTS#SS5:MissingorMis-LocatedInserts,Voids,orMis-LocatedProjectingRebar

42

TS#SS1:TROUBLESHOOTINGCORNERSPALLSINNON-PRESTRESSEDPRECAST

ELEMENTSDescription Thesespallsandcracksmaybefoundatanyedgeorcorneroftheelement

ThefollowingelementsarecoveredunderthisTroubleShootingGuide:PierElements(columns,caps),AbutmentandWallElements(stems,caps),Foundationelements(footings),orothersimilarnon-prestressedprecastelements.

CAUSE PREVENTIONA. ImproperHandling

1. Impactingedges2. Unevendunnage

A. CareinHandling1. Ensureadequateroomfortransportof

elements2. Provideuniformdunnage.Non-rigid

materialssuchastimberorelastomericpadsarerecommended

B. Production1. Bindinginformsduringstripping2. Indentationinforms3. Insertshangingupinforms4. Thermalexpansionofformspriorto

concretesetting5. Bleedingofconcreteunderheader

B. ImproveProductionMethods1. Keepformscleanandwelloiled2. Keepformsingoodcondition(repair

dents,removeprojections,andmakeseamsmortartight)

3. Ensureinsertsarefreeduringstripping4. Ensureconcretesetpriortostarting

curing5. Providemortar-tightheader

C. Design


D. VerifyDesign1. Provideproperreinforcementascloseto

edgesasclearancerequirementsallow

43

TS#SS1:TROUBLESHOOTINGCORNERSPALLSINNON-PRESTRESSEDPRECAST ELEMENTSDescription Thesespallsandcracksmaybefoundatanyedgeorcorneroftheelement

ENGINEERINGEFFECTS REPAIRCONSIDERATIONS1. Cornerspallsinbeamelementsrequire

repairtoensuresufficientloadcapacityanddurability.

2. Cornerspallsinbearingareasofbeamelementsshouldberepairedtoensureproperbearings.


1. Spallsinareasthatareexposedtotheenvironmentinthefinishedbridgeshouldberepaired.

2. Minorspallsthatdonotcompromiseprotectionfromwater,saltspray,humidity,orarenotexposedtodirectviewneednotberepaired.Forexample:spallsincorporatedintoconcreteclosurepoursorgroutedjoints.

3. Crackslocatednearcornershavethepotentialtobecomeaspallandshouldberepairedafterremovalofcrackedconcrete.

4. Wherecornerspallsaredeemedinneedofrepair,therepairsshouldbemadeinaccordancewithStandardRepairProcedure#15.

44

TS#SS2:TROUBLESHOOTINGFORCRACKSINNON-PRESTRESSEDPRECASTELEMENTSDescription Thesecracksaretypicallyperpendiculartothelongitudinalaxisoftheelementandextend

acrossthemember,oftenvisibleonmultiplefaces.ThefollowingelementsarecoveredunderthisTroubleShootingGuide:PierElements(columns,caps),AbutmentandWallElements(stems,caps),Foundationelements(footings),orothersimilarnon-prestressedprecastelements.

CAUSE PREVENTIONA. Shrinkage

1. Shrinkageofconcreteduringcuringcausingfrictionforcesbetweentheelementandtheform,leadingtoabuild-upofstressesintheelement

A.Reviewormodifythemixormodifycuringmethodstoreduceshrinkage1. Considerchangetoalternatemix(seenote)2. Applycuringcoversrapidly

B. Design1. Inadequatetemperatureandshrinkage

reinforcement

1. VerifyDesign1. Verifythatthereisadequatetemperatureand

shrinkagereinforcementandthatthereinforcementisproperlydistributedwithintheelement.

2. FormExpansionwithTemperatureRise1. Thermalexpansionoftheformcausing

frictionforcesbetweentheelementandtheform,leadingtoabuild-upofstressesintheelement.

C. LengthenSetTime-InAccordancewithASTMC4031. Minimizetemperaturedifferentialbetween

elementandform2. Preventrapidcool-downoftheelement

D. HandlingStresses

1. Highstressesduetoinadequatenumberofpickpointsorpickpointlocations.

2. Removalfromformpriortoreachingsufficientstrippingstrength.

3. Elementbindinginformsorhighsuctionforcesduringremovalfromform.

4. Unevendunnage.

3. ImproveHandlingMethods1. Checkliftingandhandlingstressesaccordingto

thePCIDesignManual.2. Verifyconcretestrengthpriortostripping.3. Adjustcalculationsforstripping.Mayleadto

higherstrippingstrengthrequirement.4. Checkelevationandseatingofdunnage.If

supportedbymorethantwopoints,checkforgapsinseatingpoints.Avoidstackingelementsontopofeachotherunlessdunnageissupportedwell(concreteslab).

Note:Modificationstomixdesignsmaynotbepossible

incertainsituationsduetoownerpre-qualificationrequirementsformixes.

45

TS#SS2:TROUBLESHOOTINGFORCRACKSINNON-PRESTRESSEDPRECASTELEMENTSDescription Thesecracksaretypicallyperpendiculartothelongitudinalaxisoftheelementandextend

acrossthemember,oftenvisibleonmultiplefaces.

ENGINEERINGEFFECTS REPAIRCONSIDERATIONS1. Thedesignanddetailingofreinforcementin

theelementshouldbecheckedinaccordancewithAASHTOtemperatureandshrinkageprovisions.

2. Anassessmentoftheneedtorepairaswellasenvironmentalexposurewillberequired.ItshouldbenotedthatAASHTOprovisionsarebasedonanassumedcrackwidthof0.017-in.withClass1Exposureand0.013-in.forClass2Exposure.Class1Exposureappliestoconditionswhencrackscanbetoleratedduetoreducedconcernsofappearanceand/orcorrosion.Class2Exposureappliestowhenthereisincreasedconcernofappearanceand/orcorrosion.

3. ACICommittee224report“ControlofCrackinginConcreteStructures”statesthattolerablecrackwidthsare0.006-in.forconcreteexposedtoseawaterspraywithwettinganddrying,0.007-in.forconcreteexposedtode-icingchemicals,and0.012-in.forconcreteexposedtohumidity.

1. Minorcracksthatareincorporatedintoconcreteclosurepoursorgroutedjointsneednotberepaired.

2. Ifthedecisionismadethatrepairsarewarranted,thecracksshouldbeepoxyinjected,inaccordancewithStandardRepairProcedure#10.

3. Experiencehasshownthatcracksasnarrowas0.002-in.canbeinjectedsuccessfully.However,thesurfaceofcracksnarrowerthan0.006-inchesshouldbesealed.SeeStandardRepairProcedure#14.

46

TS#SS3:TROUBLESHOOTINGFORHONEYCOMBING,VOIDS,POURLINES,ANDMINOR

SURFACEIMPERFECTIONSINNON-PRESTRESSEDPRECASTELEMENTSDescription Missingvolumeofcementpastefromaroundaggregateorvoidscontainingneitherpaste

noraggregate.Apourlineisadiscolorationofthesurfaceconcretebetweenadjacentconcreteplacements.Itisnotacoldjoint,wheretheearlierconcretehassetpriortoplacementofthelatterconcrete.


CAUSE PREVENTIONA. Production

1. Inadequatevibration2. Improperplacementofconcrete3. Shifted/misplacedrebarcage

A. ImproveProductionMethods1. Providethoroughinternalvibrationand,

wherewarranted,externalvibration.2. Startplacementawayfrombulkheadsand

usevibrationtocausetheconcretetoflowtowardbulkheads.

3. Verifythatreinforcingissecuredintheformsandlocatedcorrectly.

B. ConcreteMixDesign1. Inadequatemixing2. Mixtoostiff3. Earlysetinplasticizedconcrete4. Delayedplacementofconcrete5. Flashsetofconcreteinforms6. Excessiveaggregatesize,gapgrading,or

detrimentalshape

B. AdjustMixDesign1. Mixconcretethoroughly2. Adjustmixoradditivedosagerates:(add

plasticizers,reduceaggregatesize,adjustself-consolidatingadditivedose,etc.).

3. Improvedeliverytimeoftheconcrete4. Improvedeliverytimeoftheconcrete5. Coolformspriortoconcreteplacement6. Considerusingsmallerand/ordifferent

typeofaggregate.

C. DesignDetails1. Congestedreinforcing.

C. ImproveDetails1. Reducereinforcementcongestiontothe

extentpossibleProvideclearspacingbetweenreinforcementlargerthan1½timesthemaximumaggregatesize

47

TS#SS3:TROUBLESHOOTINGFORHONEYCOMBING,VOIDS,POURLINES,ANDMINOR

SURFACEIMPERFECTIONSINNON-PRESTRESSEDPRECASTELEMENTSDescription–Missingvolumeofcementpastefromaroundaggregateorvoidscontainingneitherpaste

noraggregate.Apourlineisadiscolorationofthesurfaceconcretebetweenadjacentconcreteplacements.Itisnotacoldjoint,wheretheearlierconcretehassetpriortoplacementofthelatterconcrete.

ENGINEERINGEFFECTS REPAIRCONSIDERATIONS1. Honeycombingandvoidscanaffectshear,

bendingandaxialcapacityandmustberepaired.

2. Wheretheareaistobeencasedinacast-in-placeconcreteoragroutedjoint,thehoneycombingwillnotaffectdurability.Removaloflooseaggregateandconcretepriortothepourwillbeasufficientrepairinmostcases.

1. Wheretheareaistobeexposedinthefinalcondition,considermatchingthecolorofthepatchwiththeelement.

2. Ifaestheticsarenotaconsideration,therepairofapourlineisnotnecessary,otherwisethesurfacefinishshouldrepairedbyrubbing,bagging,ordressed(similartoexposedcast-in-placeconcrete).

3. Forotherconditions,repairusingStandardRepairProcedures#5or#9,asappropriate.

48

TS#SS4:TROUBLESHOOTINGSHORTPROJECTEDREBARANDMISSINGPROJECTED

REBARINNON-PRESTRESSEDPRECASTELEMENTSDescription Thisconsistsalackof,orshortprojectingreinforcing.


CAUSE PREVENTIONA. Formwork

1. Bulkheadshift

A. ImproveProductionMethods1. Checkbulkheadlocationsandintegrity

B. ReinforcementProduction1. Improperplacement2. Impropercutting3. Improperbending4. Incorrectfabricationdrawingordesign


B. ImproveProductionMethods1. Re-checkrebarlocationspriortoconcrete

placement2. Re-checkrebarlengthsbeforecutting3. FollowCRSIrequirementsforminimum

bendingradius4. Re-checkfabricationanddesigndrawings5. Placeadditionaltiesonreinforcement6. Reviewshophandlingpractices

49

TS#SS4:TROUBLESHOOTINGSHORTPROJECTEDREBARANDMISSINGPROJECTEDREBARINNON-PRESTRESSEDPRECASTELEMENTS

Description–Thisconsistsalackof,orshortprojectingreinforcing.

MissingExternalProjectedRebarwithCorrespondingInternalBarPresent1. DrillandGroutNewExternalBar• EachmissingexternalprojectingrebarshallbereplacedbyanequivalentsizedGrade60rebar.A

newbarcanbeinstalledbydrillingandgroutinganewbarusingRepairProcedure#12.Theembedmentshallbesufficienttodevelopafulllapsplicewiththeinternalreinforcingwheretensiontransferisrequired.

• Theminimumembedmentforothersituationsshallbebasedonthechemicaladhesivemanufacturer’srecommendations.SeeStandardRepairProcedure#12

• Notethatthisrepairproceduremaynotbeacceptableiftheprojectingbaristobesplicedwithamechanicalcouplerintheadjacentelementduetopotentialalignmentissues.

ShortProjectingRebar1. UseamechanicalcouplerthatisapprovedbytheOwner.Partialremovaloftheconcrete

surroundingthebarmayberequiredinordertoattachthecoupler.Useacouplerthatcandevelopatleast125%oftheminimumspecifiedyieldstrengthofthebar.Forseismicconnections,thecouplermayneedtodevelop100%oftheminimumspecifiedtensilestrengthofthebar.

2. Installbarextensionusingcouplermanufacturer’srecommendations.SeeStandardRepairProcedure#11.

3. Ifpartialremovalofconcreteisrequired,twooptionscanbefollowed:• Iftheremovedconcreteareaiswithinaclosurepourorgroutedjointinthecompleted

structure,norepairoftheremovedconcreteisrequired.• Iftheremovedconcreteiswithintheexposedareaofconcreteinthecompletedstructure,

repairtheareausingRepairProcedure#6.

ENGINEERINGEFFECTS REPAIRCONSIDERATIONSRepairsshallnotbemadewithoutthedesigner’sapproval;thefollowingaregeneralguidelines:1. Missingprojectingreinforcementcanmateriallyaffectthedesign

oftheadjacentconnection.Ifcalculationsverifynosignificantreductionincapacity,arepairmaynotbenecessary.Ifthebarismissingwithintheelement,anengineeringassessmentoftheelementisinorder.Ifthebarisrequiredforthedesign,thenrejectionoftheelementisinorder.

2. Forbarsthataretobeinsertedintogroutedsleeves,specialcareshouldbetakentoensurethattherepairedbarwillproperlyalignwiththecoupler.

SeeBelow:

50

TS#SS5:TROUBLESHOOTINGMISSINGORMIS-LOCATEDINSERTS,VOIDS,ORMIS-LOCATEDPROJECTINGREBARINNON-PRESTRESSEDPRECASTELEMENTSDescription Thistypeofdefectconsistsofmissingormis-locatedvoidsandhardware,andmis- locatedrebar.


CAUSE PREVENTIONA. ProductionOversight

1. Bulkheadortemplateshift

A. ImproveProductionMethods1. Checkbulkheadlocationsandintegrity

B. ReinforcementProduction1. Improperplacement2. Incorrectfabricationdrawingordesign

drawing3. Shiftingduringcasting

B. ImproveProductionMethods1. Re-checkrebarandvoidlocationspriorto

concreteplacement2. Re-checkfabricationanddesigndrawings3. Placeadditionaltiesonreinforcement

51

TS#SS5:TROUBLESHOOTINGMISSINGORMIS-LOCATEDINSERTS,VOIDS,ORMIS-LOCATEDPROJECTINGREBARINNON-PRESTRESSEDPRECASTELEMENTS

Description Thistypeofdefectconsistsofmissingormis-locatedvoidsandhardware,andmis- locatedrebar.

ENGINEERINGEFFECTS REPAIRCONSIDERATIONS1. Repairsshallnotbemadewithoutthe

designer’sapproval;thefollowingaregeneralguidelines:

2. Mis-locatedreinforcementorinsertsmayleadtoimproperfit-up.Lossofthebarconnectioncanmateriallyaffectthedesignoftheadjacentconnection.Ifcalculationsverifythatthereisnosignificantreductionincapacityoftheconnection,arepairmaynotbenecessary.

3. Iftheadjacentelementhasnotyetbeencast,as-builtdimensionsmaybeappliedtotheshopdrawingsforthesubsequentelementprovidedthatthevariationdoesnotaffecttherequiredstructuralcapacityoftheconnection.

Theminimumembedmentforothersituationsshallbebasedonthechemicaladhesivemanufacturer’srecommendations.SeeStandardRepairProcedure#12

1. Ifmis-locatedinsertsandbarscannotbeeliminatedasstatedinItem1totheleft,considerdrillingandgroutinganewbarinthecorrectlocation,usingStandardRepairProcedure#12.ThenewprojectingrebarshallbeanequivalentsizedGrade60rebar.Theembedmentshallbesufficienttodevelopafulllapsplicewiththeinternalreinforcingwheretensiontransferisrequired.Ifthemis-locatedrebarlocationresultsininsufficientconcretecover,alternatecorrosionprotectionstrategiesshouldbeconsideredsuchassealersorinstallationofpassivecathodicdevices.

52

Section2.3:PrecastFullDepthDeckPanelsThereare several different typesofdetails used forprecast full-depthdeckpanels. Commondetailsinclude:

1. Fulldepthshearconnectorpockets2. Partialdepth(hidden)shearconnectorpockets3. Projectingreinforcingusedforconnections4. Panelswithpost-tensionedconnections

The graphics contained herein show several different types of details depending on theapplicabletroubleshootingguideline.

Ingeneral,thenon-conformancesnotedinthissectionareapplicabletopanelsthatareprecastorprestressed.Non-conformancesthatareonlyapplicabletoprestressedpanelsaresonoted.

TS#FDDP1:CornerSpallsTS#FDDP2:CracksTS#FDDP3:TransverseCracksTS#FDDP4:Honeycombing,Voids,andMinorSurfaceImperfectionsTS#FDDP5:ShortProjectedReinforcingandMissingProjectedReinforcingTS#FDDP6:MissingorMislocatedInserts,Voids,DuctsorMislocatedProjectingReinforcing

53

TS#FDDP1:TROUBLESHOOTINGCORNERSPALLSINPRECASTFULL-DEPTHDECKPANELSDescription Thesespallsandcracksmaybefoundatanyedgeorcorneroftheelement

Note: Thistroubleshootingguideisapplicabletobothprecastandprestressedfull- depthdeckpanels

CAUSE PREVENTIONA. Design


A. VerifyDesign1. Provideproperreinforcementascloseto

edgesasclearancerequirementsallow

B. ImproperHandling1. Impactingedges2. Unevendunnage

B. CareinHandling1. Ensureadequateroomfortransportof

elements2. Provideuniformdunnage.Non-rigid

materialssuchastimberorelastomericpadsarerecommended

C. Production1. Bindinginformsduringstripping2. Indentationinforms3. Insertshangingupinforms4. Thermalexpansionofformspriorto

concretesetting5. Bleedingofconcreteunderheader

C. ImproveProductionMethods1. Keepformscleanandwelloiled2. Keepformsingoodcondition(repair

dents,removeprojections,andmakeseamsmortartight)

3. Ensureinsertsarefreeduringstripping4. Ensureinitialconcretesetpriortostart

ofcuring5. Providemortar-tightheader

Note:Onetypeofdeckpanelshown,otherssimilar

54

TS#FDDP1:TROUBLESHOOTINGCORNERSPALLSINPRECASTFULL-DEPTHDECKPANELSDescription Thesespallsandcracksmaybefoundatanyedgeorcorneroftheelement

ENGINEERINGEFFECTS REPAIRCONSIDERATIONS1. Spallsinareasoffull-depthdeckpanelsthat

areexposedtotheenvironmentinthefinishedbridgeshouldberepaired.

2. Minorspallsthatdonotcompromiseprotectionofreinforcingfromwater,saltspray,excessivehumidity,orarenotexposedtodirectviewneednotberepaired.Forexample:spallsincorporatedintoconcreteclosurepoursorgroutedjoints.

1. Crackslocatednearcornershavethepotentialtobecomeaspallandshouldberepairedafterremovalofcrackedconcrete.

2. Wherecornerspallsaredeemedinneedofrepair,therepairsshouldbemadeinaccordancewithStandardRepairProcedure#15.


55

TS#FDDP2:TROUBLESHOOTINGFORCRACKSINFULL-DEPTHPRECASTDECKPANELSDescription Thesecracksaretypicallyperpendiculartotheaxisoftheelementandextendpartiallyor

entirelyacrossthemember,oftenvisibleonmultiplefaces.Othercracksshownbelowalsoapply.

Note: Thistroubleshootingguideisapplicabletoprecastpanelsdesignedwithmildreinforcingorpanelswithminoramountsofprestressingforhandling.Panelsdesignedwithprestressingforstrengthshouldbetreatedsimilartoaprestressedbeam.

CAUSE PREVENTIONA. Design1. Inadequatetemperatureandshrinkage

reinforcement

A. VerifyDesign1. Verifythatthereisadequatetemperatureand

shrinkagereinforcementandthatthereinforcementisproperlydistributedwithintheelement

B. Shrinkage1. Shrinkageofconcreteduringcuringcauses

frictionforcesbetweentheelementandtheform,leadingtothebuild-upofstressesintheelement

A. Reviewormodifythemixormodifycuringmethodstoreduceshrinkage

1. Considerchangetoalternatemix(seenote2)2. Applycuringcoversrapidly

B. Production/Formwork1. Thermalexpansionoftheformcausing

frictionforcesbetweentheelementandtheform,leadingtoabuild-upofstressesintheelement

2. Concretebindingtoforms3. Indentationsorjointoffsetsinforms4. Insertsinformsanchoredorrestrainedby

forms

A. ImproveProductionmethods1. Preventrapidcool-downoftheelement2. Keepformsingoodcondition;fabricateforms

withevensmoothjoints3. Keepformscleanandproperlyoiled4. Releaserestraintofallinsertsafterinitialset

C. HandlingStresses1. Highstressesduetoinadequatenumberof

pickpointsorpickpointlocations2. Removalfromformpriortoreaching

sufficientstrippingstrength3. Elementbindinginformsorhighsuction

forcesduringremovalfromform4. Unevendunnage

B. ImproveHandlingMethods1. Checkliftingandhandlingstressesaccordingto

thePCIDesignManual2. Verifyconcretestrengthpriortostripping.3. Adjustcalculationsforstripping.Mayleadto

higherstrippingstrengthrequirement4. Checkelevationandseatingofdunnage.If

supportedbymorethantwopoints,checkforgapsinseatingpoints.Avoidstackingelementsontopofeachotherunlessdunnageissupportedwell(concreteslab)

Notes:1.Onetypeofdeckpanelshown,otherssimilar2.Modificationstomixdesignsmaynotbepossibleincertainsituationsduetoownerpre-qualificationrequirementsformixes.

56

TS#FDDP2:TROUBLESHOOTINGFORCRACKSINFULL-DEPTHPRECASTDECKPANELSDescription Thesecracksaretypicallyperpendiculartotheaxisoftheelementandextendpartiallyor

entirelyacrossthemember,oftenvisibleonmultiplefaces.

ENGINEERINGEFFECTS REPAIRCONSIDERATIONS1. Thedesignanddetailingofreinforcementin

theelementshouldbecheckedinaccordancewithAASHTOtemperatureandshrinkageprovisions.

2. Anassessmentoftheneedtorepairaswellasenvironmentalexposurewillberequired.ItshouldbenotedthatAASHTOprovisionsarebasedonanassumedcrackwidthof0.017-in.withClass1Exposureand0.013-in.forClass2Exposure.Class1Exposureappliestoconditionswhencrackscanbetoleratedduetoreducedconcernsofappearanceand/orcorrosion.Class2Exposureappliestoanincreasedconcernofappearanceand/orcorrosion.

3. ACICommittee224report“ControlofCrackinginConcreteStructures”statesthattolerablecrackwidthsare0.006-in.forconcreteexposedtoseawaterspraywithwettinganddrying,0.007-in.forconcreteexposedtode-icingchemicals,and0.012-in.forconcreteexposedtohumidity.

4. Minorcracksthatareincorporatedintoconcreteclosurepoursorgroutedjointsneednotberepaired.

1. Ifthedecisionismadethatrepairsarewarranted,thecracksshouldbeepoxyinjectedinaccordancewithStandardRepairProcedure#10.

2. Experiencehasshownthatcracksasnarrowas0.002-in.canbeinjectedsuccessfully.However,thesurfaceofcracksnarrowerthan0.006-inchesshouldbesealed.SeeStandardRepairProcedure#14.


57

TS#FDDP3:TROUBLESHOOTINGFORTRANSVERSECRACKSINPRESTRESSEDFULL-

DEPTHDECKPANELSDescription Thesecracksaretypicallyperpendiculartothelongitudinalaxisoftheelementandextend

partiallyorentirelyacrossthemember,oftenvisibleonmultiplefaces.

Notes: Thistroubleshootingguideisapplicabletotransversecracksinprecastfull-depthdeckpanelswithprestressingforhandlingrunningperpendiculartothecracks.Panelswithprestressingforstrengthshouldbetreatedsimilartoaprestressedbeam.Forothercracksinprestresseddeckpanels,seeTS#FDDP2.

CAUSE PREVENTIONA. BondofStrand/StrandSlip1. StrandContamination2. Insufficientvibrationofconcrete

A. Ensureagainstunintendedstrandslip1. Inspectstrandforcleanlinessandabsenceof

lubricantsafterstressingandpriortocasting2. Useinternalandexternalvibrationincongested

endsofpanelsB. Shrinkagepriortodetensioning5. Shrinkageofconcreteduringcuringcausing

frictionforcesbetweentheelementandtheform,leadingtoabuild-upofstressesintheelement

B. Improveproductionmethods1. Applycoversrapidlyafterconcretepours2. Detensionascoversareremoved3. Preventexposedstrandfromcoolingdifferentially

withrespecttothepanel4. Adjustconcretemixbyreducingcement,adding

pozzolansorchangingaggregategradation5. Provideuniformheatandhumidity

C. DetensioningProcedure1. Lowreleasestrength2. Improperdetensioning

sequence/procedures

C. Useproperdetensioningprocedure1. Ensureproperconcretestrengthpriortorelease2. Keepprestressedforcesbalancedwhile

detensioning,usinganestablishedprocedure

D. Formwork1. Indentationsorjointoffsetsinforms2. Concretebindingtoforms

D. Inspectformconditionpriortocasting1. Ensuresmoothformalignment2. Oilformsthoroughly

E. Incorrectprestressforce1. Inadequateprestressstrandindesign2. Under-estimationofprestresslosses3. Under-tensioningofstrand4. Incorrectnumberofstrandinbed

E. Applycorrectprestressforce1. Checkdesigncalculationsandshopdrawings2. Recomputelosses3. Comparemeasuredelongationofstrandwith

computedelongation


58

TS#FDDP3:TROUBLESHOOTINGFORTRANSVERSECRACKSINPRESTRESSEDFULL-

DEPTHDECKPANELSDescription Thesecracksaretypicallyperpendiculartothelongitudinalaxisoftheelementandextend

partiallyorentirelyacrossthemember,oftenvisibleonmultiplefaces.ENGINEERINGEFFECTS REPAIRCONSIDERATIONS1. Forverticalcracksthatinterceptbonded

ordebondedstrandwithintheirrespectivetransferlengths,itisrecommendedthattheengineerre-computethemomentandshearcapacitybasedontransferinitiatingatthepointofthecrack.Ifthere-computedcapacitiesareacceptablethepanelcanberepaired.Thesecracksshouldbeinjected.

2. Verticalcracksthatinterceptbondedordebondedstrandbeyondtheirrespectivetransferlengthsandwithawidthlessthan0.006-in.afterdetensioning,neednore-evaluation.Cracks0.006-in.orgreaterinwidthshouldbeevaluatedtoaffirmadequateprestress.

3. Verticalcracksatanylocationonthepanelthatdonotinterceptstrandneednoevaluationbytheengineer.

1. Itisrecommendedthatcracksnotberepairedpriortodetensioningasrepairswillmaskthecauseandseriousnessofthecrack

2. Allcrackslessthan0.006-in.inwidth,afterdetensioninganddeemedacceptable,shouldbesealed.SeeStandardRepairProcedure#14.Ifthesecracksarewithinthetransferzone,anepoxyinjectionrepairshouldbeconsidered(seeItem3below).

3. Allcracks0.006-in.orgreaterinwidth,afterdetensioninganddeemedacceptable,shouldberepairedbyepoxyinjectioninaccordancewithStandardRepairProcedure#10.


59

TS#FDDP4:TROUBLESHOOTINGFORHONEYCOMBING,VOIDS,ANDMINORSURFACE IMPERFECTIONSINPRECASTFULL-DEPTHDECKPANELSDescription Missingvolumeofcementpastefromaroundaggregateorvoidscontainingneitherpaste

noraggregate.

CAUSE PREVENTIONA. DesignDetails6. Congestedreinforcing

A. ImproveDetails1. Reducereinforcementcongestiontothe

extentpossibleProvideclearspacingbetweenreinforcementlargerthan1½timesthemaximumaggregatesize

B. Production1. Inadequatevibration2. Improperplacementofconcrete3. Shifted/misplacedreinforcing

B. ImproveProductionMethods1. Providethoroughinternalvibrationand,

wherewarranted,externalvibration2. Startplacementawayfrombulkheadsand

usevibrationtocausetheconcretetoflowtowardbulkheads

3. Verifythatreinforcingissecuredintheformsandlocatedcorrectly

C. ConcreteMixDesign1. Inadequatemixing2. Mixtoostiff3. Earlysetinplasticizedconcrete4. Delayedplacementofconcrete5. Flashsetofconcreteinforms6. Excessiveaggregatesize,gapgrading,or

detrimentalshape

C. AdjustMix1. Mixconcretethoroughly2. Adjustmixoradditivedosagerates:(add

plasticizers,reduceaggregatesize,adjustself-consolidatingadditivedose,etc.)

3. Improvedeliverytimeoftheconcretelformspriortoconcreteplacement

4. Considerusingsmallerand/ordifferenttypeofaggregate

60

TS#FDDP4:TROUBLESHOOTINGFORHONEYCOMBING,VOIDS,ANDMINORSURFACE IMPERFECTIONSINPRECASTFULL-DEPTHDECKPANELSDescription Missingvolumeofcementpastefromaroundaggregateorvoidscontainingneitherpaste

noraggregate.

ENGINEERINGEFFECTS REPAIRCONSIDERATIONS1. Wheretheareaistobeencasedinacast-in-

placeconcreteoragroutedjoint,thehoneycombingwillnotaffectdurability.Removaloflooseaggregateandconcretepriortothepourwillbeasufficientrepairinmostcases.

1. Forotherconditions,repairusingStandardRepairProcedures#5or#9,asappropriate.

61

TS#FDDP5: TROUBLESHOOTINGSHORTPROJECTEDREINFORCINGANDMISSING

PROJECTEDREINFORCINGINPRECASTFULL-DEPTHDECKPANELS

Description Thisconsistsofalackoforshortprojectingreinforcing.

CAUSE PREVENTIONA. Formwork1. Bulkheadshift

A. ImproveProductionMethods1. Checkbulkheadlocationsandintegrity2. Reviewqualitycontrolproceduresforpre-

pourandadjustasneeded

B. ReinforcementProduction1. Improperplacement2. Impropercutting3. Improperbending4. Incorrectfabricationdrawingordesign


B. ImproveProductionMethods1. Re-checkreinforcinglocationspriorto

concreteplacement2. Re-checkreinforcinglengthsbeforecutting3. FollowCRSIrequirementsforminimum

bendingradius4. Re-checkfabricationanddesigndrawings5. Placeadditionaltiesonreinforcement6. Reviewqualitycontrolproceduresforpre-

pourandadjustasneeded7. Reviewshophandlingpractices

62

TS#FDDP5: TROUBLESHOOTINGSHORTPROJECTEDREINFORCINGANDMISSING

PROJECTEDREINFORCINGINPRECASTFULL-DEPTHDECKPANELS

Description–Thisconsistsofalackof,orshortprojectingreinforcing.

MissingExternalProjectedReinforcingwithCorrespondingInternalBarPresent1. DrillandGroutNewExternalBar• Eachmissing external projecting reinforcing shall be replaced by a bar of equivalent size and

grade. A new bar can be installed by drilling and grouting a new bar using Standard RepairProcedure#12.Theembedmentshallbesufficienttodevelopafull lapsplicewiththeinternalreinforcingwheretensiontransferisrequired.

• The minimum embedment for other situations shall be based on the chemical adhesivemanufacturer’srecommendations.SeeStandardRepairProcedure#12

• Notethatthisrepairproceduremaynotbeacceptableiftheprojectingbaristobesplicedwithamechanicalcouplerintheadjacentelementduetopotentialalignmentissues.

ShortProjectingReinforcing1. Use a mechanical coupler that is approved by the Owner. Partial removal of the concrete

surroundingthebarmayberequiredinordertoattachthecoupler.Useacouplerthatcandevelopat least 125% of theminimum specified yield strength of the bar. For seismic connections, thecouplermayneedtodevelop100%oftheminimumspecifiedtensilestrengthofthebar.

2. Install bar extension using coupler manufacturer’s recommendations. See Standard RepairProcedure#11.

3. Ifpartialremovalofconcreteisrequired,twooptionscanbefollowed:• Iftheremovedconcreteareaiswithinaclosurepourorgroutedjointinthecompletedstructure,

norepairoftheremovedconcreteisrequired.• Iftheremovedconcreteiswithintheexposedareaofconcreteinthecompletedstructure,repair

theareausingStandardRepairProcedure#6.

ENGINEERINGEFFECTS REPAIRCONSIDERATIONSRepairsshallnotbemadewithoutthedesigner’sapproval;thefollowingaregeneralguidelines:1. Missingprojectingreinforcementcanmateriallyaffectthedesign

oftheadjacentconnection.Ifcalculationsverifynosignificantreductionincapacity,arepairmaynotbenecessary.Ifthebarismissingwithintheelement,anengineeringassessmentoftheelementisinorder.Ifthebarisrequiredforthedesign,thenrejectionoftheelementisinorder.

SeeBelow:

63

64

TS#FDDP6:TROUBLESHOOTINGMISSINGORMISLOCATEDINSERTS,VOIDS,DUCTSORMISLOCATEDPROJECTINGREINFORCINGINPRECASTFULL-DEPTHDECKPANELS

Description Thistypeofdefectconsistsofmissingormis-locatedvoids,ducts,hardware,andmis- locatedreinforcing.

CAUSE PREVENTIONA. ProductionOversight1. Bulkheadortemplateshift

A. ImproveProductionMethods1. Checkbulkheadlocationsandintegrity2. Reviewqualitycontrolproceduresforpre-

pourandadjustasneeded

B. ReinforcingProduction1. Improperplacement2. Incorrectfabricationdrawingordesign

drawing3. Shiftingduringcasting

B. ImproveProductionMethods1. Re-checkreinforcingandvoidlocationsprior

toconcreteplacement2. Re-checkfabricationanddesigndrawings3. Placeadditionaltiesonreinforcement

65

TS#FDDP6:TROUBLESHOOTINGMISSINGORMISLOCATEDINSERTS,VOIDS,DUCTSORMISLOCATEDPROJECTINGREINFORCINGINPRECASTFULL-DEPTHDECKPANELS

Description Thistypeofdefectconsistsofmissingormis-locatedvoids,ducts,hardware,andmis- locatedreinforcing.

ENGINEERINGEFFECTS REPAIRCONSIDERATIONSRepairsshallnotbemadewithoutthedesigner’sapproval;thefollowingaregeneralguidelines:

1. Mislocated reinforcement or inserts maylead to improper fit-up. Loss of the barconnection can materially affect the designof the adjacent connection. If calculationsverifythatthereisnosignificantreductionincapacityoftheconnection,arepairmaynotbenecessary.

2. If themislocated reinforcing location resultsin insufficient concrete cover, alternatecorrosion protection strategies should beconsidered such as sealers or installation ofpassivecathodicdevices.

3. Thecontractorcanattempttodetermineifamislocated shear connector void is able toaccommodatetherequirednumberofshearconnectors. If it is feasible to install theconnectors within the misaligned void, itmaybepossibletousethepanel.

4. Ifapost-tensioningductisslightlymisaligned(beyond the specified tolerances), theContractor can attempt to determine if themisaligned duct can be properly connectedand sealed with the duct in the adjacentpanel.TheContractorshallalsodetermineifthe tendons can be installed in themisaligned duct. If the misaligned ductcannotbeused,thepanelshouldberejectedandanewpanelcast.Ifitisdeterminedthatthe misalignment is acceptable, theContractor will be responsible for anyproblemsthatariseduringinstallation.Ifthemisalignment of the duct results in aneccentricity of the tendon, a review by theEngineerisrequired.

1. If mislocated inserts and bars cannot beeliminated as stated in Item 1 to the left,considerdrillingandgroutinganewbarinthecorrect location, using Standard RepairProcedure #12. The new projectingreinforcing shall be an equivalent size andgradeofreinforcing.Theembedmentshallbesufficienttodevelopafull lapsplicewiththeinternal reinforcingwhere tension transfer isrequired.

2. The minimum embedment for othersituations shall be based on the chemicaladhesive manufacturer’s recommendations.SeeStandardRepairProcedure#12

66

Section3:StandardRepairProcedures

1. ConfinedSpallsInsideBearingAreas 2. ConfinedSpallsOutsideBearingAreas 3. Non-ConfinedBearingAreaSpalls 4. SpallsandVoidsintheBottomFlangeThatExposePrestressingStrand 5. HoneycombedorVoidedWebAreas 6. DamagedFlangesRequiringRemovalandReplacementofConcrete 7. TakingCoresandPatchingCoredHolesinGirders 8. MisshapenBearingRecesses 9. HoneycombedAreasLeft-in-Place 10. EpoxyInjectionofCracks 11. ShortProjectingMildReinforcingBarsorProjectingPrestressingStrands 12. ReplacementofMissingProjectedMildSteelorPrestressingStrand 13. MissingorIncorrectlyLocatedDiaphragmInserts 14. SealingCracks

15. EdgeSpallsinPrecastElements AsuggestedreferenceforguidanceonrepairmethodsisthePCIDocumententitledManualfortheEvaluationandRepairofPrecast,PrestressedConcreteBridgeProducts[6].Thisdocumentcontainssimilarinformationasthisdocument,howeveralsocontainsachapteronMethodsofPatching.

67

STANDARDREPAIRPROCEDURE#1FORCONFINEDSPALLSINSIDEBEARINGAREAS

CASE1:NOSTRANDSEXPOSEDA. Remove all loose concrete, taking care to not damage

reinforcingorstrand.

B. Square all sides of the depression. Take care to notdamageanymildreinforcement.

C. Cleantheexcavatedareaandreinforcingwithastiffwire

brush,blowingawaydust,withhighpressureair.

D. Repair Option 1 – Fill the voided area using approvedpolymermodifiedcementitious,shrinkage-compensatedpatchingmaterial,withacompressivestrengthequaltoor greater than the specified design strength of thebeam. Prepackaged patching material is preferred tocontrolquality.Cureproperly.

E. RepairOption2–Coatsurfacetobeadheredtowithan

approvedbondingagent, followingthemanufacturer’s instructions.Fill thevoidedareawithahigh strength, cement based, shrinkage-compensated mortar, following the manufacturer’sinstructions.Cureproperly.

F. Usecaretoensurethattherepairedareadoesnotprojectbelowthebottomoftheflangenear

thebearingarea.NOTE:Withthepriorapprovaloftheowner/engineer,spallsthatinvolvenomorethan20%ofthebearingareamaybepatched,inthepresenceoftheowner’sinspectorwithoutsubmittingtherepairforformalapproval.Repairsofspallsinexcessof20%ofthebearingareawillrequiresubmissionofarepairplantotheowner/engineerforapproval.CASE2:STRANDSEXPOSEDThefullextentofstrandexposureshallbedeterminedandarepairplansubmittedforapprovalbytheowner/engineer,regardlessofthesizeofthespall,asthedesigncapacitymaybeaffected.Generally,ifthedesigncapacityisjudgedtohavenotbeendiminished,ordiminishedanacceptableamount,therepairproceduresforCase1willremainapplicable.

68

STANDARDREPAIRPROCEDURE#2FORCONFINEDSPALLLSOUTSIDEBEARINGAREASCASE1:Nostrandsexposed;spalllocatedbetweentheendofthebeamandthe¼point.

A. Withthepriorapprovaloftheowner/engineer,individualspallsorcollectivemultiplespallsnotexceeding10%ofthebottomflangeplanarea,withinthedefinedlimits,mayberepairedinthepresenceoftheinspectorutilizingeitherrepairoptionspecifiedinStandardRepairProcedure#1.

B. Ifanindividualspallorcollectivemultiplespallsexceed10%ofthebottomflangeplanarea,arepairplanmustbesubmittedtotheowner/engineerforapproval.

CASE2:NoStrandsExposed:Spalllocatedbetweenthe¼pointand½pointofthebeam.

A. Withthepriorapprovaloftheowner/engineer,individualspallsorcollectivemultiplespallsnotexceeding10%ofthebottomflangeplanarea,withinthedefinedlimits,mayberepairedinthepresenceoftheinspector.TherepairoptionsdescribedinStandardRepairProcedure#1maybeused,howeveranapprovedshrinkagecompensatingpatchmaterial,withacompressivestrengthmeetingthedesignstrengthofthebeam,mustbeused.

CASE3:StrandsExposed

A. Spallslocatedanywhereonthebottomofthebeamflangethatexposesstrandsrequiressubmissionofarepairplanforapprovalbytheowner/engineer.Thefullextentofstrandexposureshouldbeidentified.Generally,ifthedesigncapacityisjudgedtohavenotbeendiminishedordiminishedanacceptableamount,therepairproceduresforCases1&2,asapplicable,maybeused.

Note:Incaseswherethepatchislocatedovervehiculartrafficorpedestrianwalkways,thepatchingmaterialmustbemechanicallyanchoredeitherbyencapsulatingexistingreinforcement,beanchoredbysupplementalreinforcement,orbyotheranchoringdevices.

69

STANDARDREPAIRPROCEDURE#3FORNON-CONFINEDBEARINGAREASPALLS

A. Removealllooseconcrete.

B. Square interface with existing concrete to be incontact with the patch, to the extent practical. Takecare to not damage any mild reinforcement orprestressingstrands.

C. Cleantheexcavatedarea,blowingawaydust.

D. Repair Option 1 – Fill the spall area with approved

polymer modified cementitious, shrinkage-compensated patching material, with a compressivestrengthequaltoorgreaterthanthespecifieddesignstrengthofthebeam.Pre-packagedpatchingmaterialispreferredtocontrolquality.

E. RepairOption2–Coatsurfacetobeadheredtowith

an approved bonding agent, following themanufacturer’s instructions. Fill the spall areawith ahighstrength, cementbased, shrinkage-compensatedmortar,followingthemanufacturer’sinstructions.

F. Incaseswherethepatchis locatedovervehiculartrafficorpedestrianwalkways,thepatching

material must be mechanically anchored either by encapsulating existing reinforcement, beanchoredbysupplementalreinforcement,orbyotheranchoringdevices.

NOTE:Withthepriorapprovaloftheowner/engineer,spallsintheendregionsofthebeam,withintheboundsstatedherein,maybepatched,inthepresenceoftheowner’sinspectorwithoutsubmittingtherepairforformalapproval.Repairsofspallslargerthanshownhereinwillrequiresubmissionofarepairplantotheowner/engineerforapproval.

70

STANDARDREPAIRPROCEDURE#4FORSPALLSANDVOIDSINTHEBOTTOMFLANGETHATEXPOSEPRESTRESSINGSTRANDRepairs at beam ends should be made after detensioningbecause any repairs made prior to detensioning will mostlikelyfailduetohightransferstresses.Repairs away from beam ends should be made prior todetensioningsothatprecompressionstressesare induced inthepatchmaterial.


B. Square interfaces with existing concrete to be incontactwiththepatch.


RepairOption1–Fillthevoidedareawithapprovedpolymer modified cementitious, shrinkage-compensated patchingmaterial, with a compressivestrengthequaltoorgreaterthanthespecifieddesignstrengthofthebeam.Prepackagedpatchingmaterialispreferredtocontrolquality.

D. RepairOption2–Coatsurfacetobeadheredtowithanapprovedbondingagent,followingthemanufacturer’sinstructions.Fillthevoidedareawithahighstrength,cementbased,shrinkage-compensatedmortar,followingthemanufacturer’sinstructions.

E. Detensioning should not occur until the patch reaches the specified compressive release

strength.

F. For largerspallsofasimilarnatureand/or involvingmorestrands,thesamerepairtechniquesmaybeemployedbutmustbesubmittedtotheowner/engineerforevaluationandapproval.

G. Forareaswithextremeexposure, silaneorothersealantsmayalsobeappliedover thepatcharea.

NOTES:

1. Incaseswherethepatchis locatedovervehiculartrafficorpedestrianwalkways,thepatchingmaterial must be mechanically anchored either by encapsulating existing reinforcement, beanchoredbysupplementalreinforcement,orbyotheranchoringdevices.

2. Thisrepairappliesonlytothosevoidswhichdonotexceed4 inches indepth,4feet in lengthandexposenomorethan2strands,andwhennomorethanonespallorvoidappearsinagivensectionof thegirder.Asection isdefinedas¼ the lengthof thegirder.No twosuchspallsorvoids shall have their closest dimensions nearer than two beamdepths apart.With the priorapproval of the owner/engineer, this repair may be made, in the presence of the owner’sinspectorwithoutsubmittingtherepairforformalapproval.

71

72

STANDARDREPAIRPROCEDURE#5FORHONEYCOMBEDORVOIDEDWEBAREASCASE1:Nostrandexposed,butreinforcingexposed

A. Remove all loose concrete with a maximum 15 poundpneumaticchippinghammer.

B. Squareallsidesofthedepressionexceptthetopofthevoid.

Bevelthesurfaceasshowninthedetailonthissheet.


D. Repair Option 1 – Fill the voided area with an approvedmodified cementitious shrinkage compensated patchingmaterial with a compressive strength equal to or greaterthanthespecifieddesignstrengthofthebeam.Prepackagedpatchingmaterialispreferredtocontrolquality.

E. Repair Option 2 – Coat surface to be adhered with an

approved bonding agent, following the manufacturer’sinstructions.Fillthevoidedareawithahighstrength,cementbased, shrinkage-compensated mortar, following themanufacturer’sinstructions.

NOTE:Withthepriorapprovaloftheowner/engineer,individualareaswithawidth,measuredverticallynotgreaterthan20%ofthewebdepthandalength,measuredhorizontallynotgreaterthan½thewebdepthmayberepaired,inthepresenceoftheowner’sinspector,withoutformalsubmissionofarepairplanforapproval.CASE2:StrandsexposedorareasexceedingthosedefinedinCase1:

A. Itmaybepossibletoemploythesamerepairtechniquesasabove,butarepairplanthatindicatestheextentofstrandexposuremustbesubmittedtotheowner/engineerforevaluationandapproval.

SPECIALDETAILFORVERTICALPATCHING

73

STANDARDREPAIRPROCEDURE#6FORDAMAGEDFLANGESREQUIRINGREMOVALANDREPLACEMENTOFCONCRETEPreferably, these repairs should be made prior to detensioning,however, this type damage can occur in handling afterdetensioning.CASE1:Thebeamwillsubsequentlybetopped with a compositestructuralslab

A. Removealllooseconcrete

B. Preserve and thoroughly clean allmild reinforcement. Ifreinforcement is epoxy coated, touch-up all damagedareas

C. Cleantheremainingconcretecontactsurfaces

D. Repair Option 1 – Re-pour the missing section with

approved polymer modified, cementitious, shrinkagecompensated patching material, with a compressive andtensile strength equal to or greater than the designstrength of the beam. Prepackaged material is preferredforqualitycontrol.

E. RepairOption2–Coatthesurfacestobeadheredtowith

anapprovedbondingagent, following themanufacturer’sinstructions. Re-pourwithconcretehavingacompressivestrength equal to or greater than the design strength ofthe beam. Moist cure in accordance with contractspecifications.

CASE 2: The beam flange is the final riding surface or will beoverlaidbyanon-structuralridingsurface.Undertheseconditionstheowner/agentshouldbeconsultedastoareasthatmayberepairedusingStandardRepairProcedures.NOTE:With prior approval of the owner/engineer, areas definedmayberepairedinthepresenceoftheowner’sinspectorwithoutformal submission of a repair plan. Larger area repairs require aformal submission of a repair plan to the owner/engineer forapproval.

74

STANDARDREPAIRPROCEDURE#7FORTAKINGCORESANDPATCHINGCOREDHOLESINGIRDERSThisprocedureappliestothesamplingbycoringandthepatchingofholes.Coresmayberequiredforsituationswheretheconcretestrengthofthegirderisinquestion.

A. Obtain coresof thediameter specifiedby theowner/engineer. Theengineer shall determinethe location of the core in the member. Preference should be given to areas that will becovered with concrete in the completed structure (i.e. within cast diaphragms, top of topflanges,etc.)

B. Locateandmarkallreinforcementandprestressingstrandinthevicinityofthecore.

C. Coreholes,avoidingreinforcingsteelandprestressingstrands.

D. Coatthecoredholeswithanapprovedbondingagent.

E. Patchusinganapprovedhighstrengthnon-shrinkorpolymermodified,cementitiousshrinkage

compensated prepackage patching material in accordance with the manufacture’srecommendations.

F. Allworkmustbewitnessedbytheowner’sinspector.

75

STANDARDREPAIRPROCEDURE#8FORMISSHAPENBEARINGRECESSESThisrepairappliestothosebearingrecessesthatareconcave,convex,slopinginthewrongdirectionordimensionallyoutoftolerance.

A. Chip out surface to achieve correct profile or to intentionally roughen to accept patchingmaterial.

B. Cleanbearingrecessofallunsoundmaterial.

C. Applyasolutionofwaterandlatexorotherapprovedbondingagenttotheareatobefilled.

D. Mixamortarconsistingof5partsNo.70silicasandand4partscementwithlatexandwaterto

a dry consistency. (For more information on dry consistency, see Section 4) Use of a highstrength,non-shrinkgroutisalsoacceptable.

E. Applythismortarmixtoproducethespecifiedrecessdimensions.

F. Re-checkthebearingsurface,toensurethatalldimensionaltolerancesaresatisfiedassetforth

inowner’sStandardSpecifications.

76

STANDARDREPAIRPROCEDURE#9FORHONEYCOMBEDAREASLEFT-IN-PLACENOTE:Repairprocedures#1through#5coverspallsandvoids. They are equally applicablewhere it isdeemedappropriatetoremove honeycombed constituents and fill the voids with cementitiousmaterials used for patching. Inmany cases it is desirable to repair honeycombed areas by filling thevoidswithpressureinjectedepoxyresinbinders.

A. Chipout½to1inchoftheexposedfaceofhoneycombedarea.

B. Apply a seal coat of polymer modified cementitiousshrinkage-compensated patching material, having acompressive strength equal to or greater than the designstrengthofthebeam.

C. Insert injection tubes through the freshly applied seal coat

such that the tubes penetrate beyond the coating into thehoneycombedarea(asanalternatetoBandC, inserttubesthrough hole drilled into hardened seal coat and then sealtheannularspacebetweenholesandtubes.)

D. InjectlowviscosityepoxyorPortlandcementgroutintothe

honeycombed area, using successive port-to-port injectionmethods,startingatthelowesttubelocation,takingcarenottoentrapairpockets

E. Pinchofftubesasinjectionofitspartiscompleted.

NOTE:UseofPortlandcementgroutisequallyacceptabletoepoxyforfillingthevoids.NOTE:Withpriorapprovaloftheowner/engineer,honeycombedvoidswithinthelimitationsdescribed

in standard repairprocedures#1 through#5maybe injectedwithapprovedepoxymaterialorPortland cement grout, in the presence of the owner’s inspector. For areas greater than thelimitationsinprocedures#1through#5,formalsubmissionofrepairproceduresarerequired.

77

STANDARDREPAIRPROCEDURE#10FOREPOXYINJECTIONOFCRACKSThis procedure applies to cracks that occur in the precastmemberwithacrackwidthgreaterthan0.006inches.All workmen engaged in the injection process shall havesatisfactorily completed a program of instruction in thespecificepoxyinjectionprocesstobeused.The specific epoxy resin adhesive usedmust be approvedbytheowner/engineer.Surfacesealmaterial,usedtoconfinetheinjected adhesive, must have adequate strength to hold anyinjection fittings firmly in place and to resist injectionpressuresandpreventleakage.Epoxy components shall be mixed in accordance with themanufacturer’srecommendationsandexpendedordiscardedinaccordancewiththemanufacturer’sdesignatedpotlife.Injection equipment used must be capable of delivering thepressureappropriatefortheinjectionrequirements.CASE1:Cracksaccessibleandvisiblefrombothsides

A. Prepare areas adjacent to the crack, cleaning away dirt, dust, grease, oil and other foreignmatterdetrimentaltothebondingoftheinjectionsurfacesealsystem.Corrosivesshouldnotbeusedforcleaning.

B. For cracks of sufficient width to permit entry of loose particles, blow out debris using highpressureairequipmentcapableoffilteringoutanyoilsfromthecompressor.

C. Applyanappropriatesurfaceseal,tobothsidesofthecrack,allowingsufficientcuringtime.

D. Installinjectionportsatintervalsnotlessthaneightinches.(Note:Themaximumportspacingisafunctionofcrackwidthandpumppressureandreliesonjudgementandinjectionequipmentused).

E. For essentially horizontal cracks, begin at either end of the crack. For cracks exhibiting any

verticality inorientation,startat the lowestport.Beginandcontinue injectingepoxyuntil theadhesivereachesthenextport.

78

STANDARDREPAIRPROCEDURE#10FOREPOXYINJECTIONOFCRACKS(CONTINUED)

F. Clamp or otherwise seal off the port and begin injecting through the next port. Do not skip

successiveports, inordertoavoidentrapmentofairwhichwillpreventcompletefillingofthecrack.

G. Performtheinjectionprocedurecontinuouslyuntiltheentirecrackisfilled.Ifport-to-porttravel

oftheadhesiveisnotindicated,immediatelyceaseinjectionandnotifytheengineer.Determinethecauseofproblembeforecontinuing.

H. Wheninjectioniscomplete,allowtheadhesivetocurethelengthoftimeandmannerspecified

bythemanufacturer.

I. Remove the surface seal by grinding so that the face of the crack is flush with the adjacentconcretesurfaces,withnodepressionsattheentryports.

J. Ifthefacesofthebeamarenottobesubsequentlytexturecoated,applyacolor-matchingsand

andcementmix.CASE2:BlindCracks,NotVisibleorAccessibleFromBothSides

Use the same procedures described in Case 1 with the exception that port spacing shall notexceedthethicknessofthememberforthroughcracks.(Examplesarecracksthroughtheweborflangesofboxbeams.)

NOTE: Sample cores of completed injections may be needed to verify the effectiveness of the

proceduresusedinbothCase1and2.Allworkshouldbeaccomplishedinthepresenceoftheowner’sinspector.

79

STANDARDREPAIRPROCEDURE#11FORSHORTPROJECTINGMILDREINFORCINGBARSORPROJECTINGPRESTRESSINGSTRANDSCASE1:BrokenorShortMildSteelReinforcementusedasStirrupsorEndProjections

A. MechanicalCouplerAn approved coupler may be used, provided enough bar projection remains to install thecoupler.Thecouplershallbeinstalledaccordingtothemanufacturer’srecommendations.

B. Welding

Asanalternativetoacoupler,weldingmaybeconsidered.Fornormallynon-weldablegradesofreinforcing,suchasASTMA615,weldingofthesteelshouldbeapproachedwithcautionsinceno specific provisions have been included in the particular ASTM specification to enhanceweldability.Whennominallynon-weldablesteel is tobewelded,aweldingproceduresuitablefor the chemical composition and intended use of the barmust be prepared. The use of thelatesteditionofANSI/AWSD1.4isrecommended.Forweldablegradesofmildreinforcement,useofANSI/AWSD1.4negatestheneedforaseparateweldprocedure.

Butt weld the additional segment to achieve the plans projection. All welding must be inconformance with AWS welding procedures for reinforcing steel. Bar preheat should bedetermined from the carbon content and carbon equivalent (Determined from millcertifications).Weldinggroundmustbeplaceddirectlyonthereinforcingbarbeingweldedandimmediatelyadjacenttotheweld.Groundingthroughthegirderisstrictlyprohibited.

Allworkistobewitnessedbytheowner’sinspector.

CASE2:BrokenorShortPrestressingStrandEndProjections

A. Selectaproprietarystrandcouplingdevicecapableofreachingorexceedingtheyieldstrengthoftheprestressingstrand.

B. Cutoffstrandtoalengthappropriateforsplicingandjointheadditionallengthstrandrequired.

NOTE:Asanalternate to the repairsoutlined inCase1and2, itmaybeacceptable todrillandgroutreplacementbarorstrand.SeeStandardRepairProcedure#12.

80

STANDARDREPAIRPROCEDURE#12FORREPLACEMENTOFMISSINGPROJECTEDMILDSTEELORPRESTRESSINGSTRANDNOTE:Unlessotherwiserequiredbytheowner/engineertosatisfydesignrequirements,thefollowing

procedureisdeemedacceptable.

A. Drilltheholediametertotheoversizedimensionsuggestedbythechemicaladhesivemanufacturer’srecommendation,accountingfortheupsetlugs.RefertotheTroubleshootingGuide#10fortherequireddepthofthehole.Theholeshallbeaminimumof3”fromanybeamedge,measuredfromtothecenterlineofthebar.

B. Afterdrillingthehole,blowoutanyresidueusingfilteredcompressedair.

C. Packtheholewithchemicaladhesiveoftheproperviscosityasrecommendedbythe

manufactureroftheadhesive,whichdependsontheorientationofthehole.

D. Rotateandpushthebarorstrandintotheholeuntilseatedatthebottom.Donotdrivethebarwithpercussiontools.

E. Thechemicaladhesiveshallbeontheowner/engineerapprovedproductslist,forthe

applicationintended,orotherwisesubmittedforapprovalpriortouse.

F. Allworkshouldbewitnessedbytheowner’sinspector.

81

STANDARDREPAIRPROCEDURE#13FORMISSINGORINCORRECTLYLOCATEDDIAPHRAGMINSERTS

A. Drillhole¼-inchgreaterthanthenominaldiameterofthebar.Thedepthofholeshouldbe1-inchlessthanstemwidth.

B. Fillholewithnon-sagchemicaladhesivefollowingmanufacturer’sinstructions.

C. Insert rebar and maintain in position until the chemical adhesive cures per manufacturer’s

instructions.NOTE: The path of the deflected strand should be determined and marked along the web prior to

drilling.

SECTION

82

STANDARDREPAIRPROCEDURE#14FORSEALINGCRACKSCRACKSONHORIZONTALSURFACESNOTE:This repairprocedureaddressessealingcracksonhorizontal surfaceswitha lowmodulus,high

molecularweightmethacrylatepenetratingsealerandcrackfiller.

A. FollowtheManufacturer’srecommendationsfortheapplicationofthematerial.

B. Thespecificmethacrylatesealermaterialshallbeapprovedbytheowner/engineer.

C. Substrateshallbeclean,soundandfreeofsurfacemoisture. Removedust, laitance,andoils,curingcompoundsandallotherforeignmaterialbymechanicalmeans.

D. Cracks extending through the entiremember thickness shall be sealed from theunderside to

preventleakage.

E. The methacrylate sealer shall be applied to the surface according to manufacturer’srecommendationsandallowedtopondover thecrack. In somecases itmaybenecessary tobuildatemporarydamoneithersideofthecracktofacilitateponding.

F. The treated surface can become smooth after curing. A dry sand can be broadcast on the

partiallycuredsurfaceifasmoothsurfaceisundesirable.CRACKSONVERTICALSURFACESNOTE: Thisrepairprocedureaddressessealingcracksonverticalsurfaceswithvariousmaterials.I.EPOXYPASTE:

Anepoxypasteappliedbyhandandworkedintocrackscanprovideaneffectivemoistureseal.Thistypeofrepairistypicallyusedtosealindividualcracks.Thematerialusedshallbeapprovedbytheowner/engineerandappliedaccordingtomanufacturer’srecommendations.

A. Surfacepreparation

1. Surfacetobecleanandsound2. Surfacemaybedampordry3. Substratemust be 40 degrees F and rising with preferred temperatures ranging from 40

degreesFtonohigherthan80degreesF

B. Applicationoftheepoxypaste1. Preparetheepoxypasteaccordingtothemanufacturer’srecommendations2. Usinga thin, flexible,andsquareended,plasticornylonspatula, force theepoxygelwith

uniformpressurebysqueegeeactionintothecracks3. Fingerapplicationtothecracks ispermissible,butuniformity infillingofthecracks isbest

accomplishedwiththeactionofaspatula4. Allowtosetuntiltackfree.NoteWell:thisisatemperaturedependentprocessandat40F

andrisingthesettimewillbelongerthanat75degreesF5. Lightlyhandsandtheareatomatchtextureandappearanceofadjacentareasnotrepaired

83

STANDARDREPAIRPROCEDURE#14FORSEALINGCRACKS(CONTINUED)

II.SILANEANDSILOXANESYSTEMS:

Asilaneorsiloxanebasedwater repellentscanbeapplied to thesurfacesurroundingacrack.Experiencehasshownthatthesealerswillwickintoandsealcracks≤0.013”inwidth.Multipleapplicationsmayberequired.Thistypeofrepairistypicallyusedonalargenetworkorseriesoffinecracks.Thematerialusedshallbeapprovedbytheowner/engineerandappliedaccordingtomanufacturer’srecommendations.

A. Applicationofbreathablewaterrepellent:silaneorsiloxanesytems

1. Power mix materials per manufacturer’s recommendations for the time specified, andperiodicallythereaftertoensureuniformproduct

2. Applywithpaintbrush,rollerorsprayerfromthebottomuponverticalsurfaces3. Applytosaturationpermanufacturersrecommendations

METHACRYLATE:

Alowmodulus,highmolecularweightmethacrylatesealercanbeintroducedintocracksatanyorientationusingavacuum-impregnationprocess.Thistypeofrepaircanbeusedonaseriesoffine cracks and on individual cracks. The cracks are prepared in a similar fashion to thoseundergoing an epoxy injection repair. The vacuum-impregnation process is patented byBALVAC,Inc.

84

STANDARDREPAIRPROCEDURE#15FOREDGESPALLSINPRECASTELEMENTSNOTE:Thisrepairappliesonlytothosevoidsinprecast(includingprecastelementswithprestressingforhandling) which do not exceed 4 inches in depth, 4 feet in length. With the prior approval of theowner/engineer,thisrepairmaybemade,inthepresenceoftheowner’sinspectorwithoutsubmittinganon-conformancereportforformalapproval.


B. Squareinterfaceswithexistingconcretetobeincontactwiththepatch.


D. RepairOption1–Fillthevoidedareawithapprovedpolymermodifiedcementitious,shrinkage-compensated patching material, with a compressive strength equal to or greater than thespecifieddesignstrengthoftheelement.Prepackagedpatchingmaterialispreferredtocontrolquality.

E. RepairOption2–Coatsurfacetobeadheredtowithanapprovedbondingagent,followingthe

manufacturer’sinstructions.Fillthevoidedareawithahighstrength,cementbased,shrinkage-compensatedmortar,followingthemanufacturer’sinstructions.

F. Forlargerspallsofasimilarnatureand/orinvolvingreinforcing,thesamerepairtechniquesmay

beemployedbutmustbesubmittedtotheowner/engineerforevaluationandapproval.NOTE: Incaseswhere thepatch is locatedovervehicular trafficorpedestrianwalkways, thepatchingmaterialmustbemechanicallyanchoredeitherbyencapsulatingexistingreinforcement,beanchoredbysupplementalreinforcement,orbyotheranchoringdevices.

85

86

Section4:ReferencesGENERAL

1. Precast/PrestressedConcreteInstitute.ManualforQualityControlforPlantsandProductionof

Structural Precast ConcreteProducts,Fourth Edition,MNL-Il6. Chicago, IL: Precast/PrestressedConcreteInstitute,1999.

2. Precast/Prestressed Concrete Institute. Bridge Design Manual, Third Edition, MNL-133-11.Chicago,IL:Precast/PrestressedConcreteInstitute,2011.

3. Neville,A.M.PropertiesofConcrete,FourthandFinalEdition.NewYork,NY:JohnWiley&Sons,Inc.,1996.

4. Zia, P. and Caner, A. October 1993. Cracking in Large-Sized Long-Span Prestressed ConcreteAASHTO Girders, Final Report, Research Project 23241-93-3 (FHWAINC/94-003). Center forTransportation Engineering Studies, Department of Civil Engineering. Raleigh, NC: NorthCarolinaStateUniversity.

5. Zhifu, Y., Brown, H., Huddleston, J. and Segar, W, Performance evaluation of rapid-setprepackaged cementitious materials for rehabilitation of surface distress of concretetransportationstructures,PCIJournal,Precast/PrestressedConcreteInstitute,March-April2016

6. Precast/Prestressed Concrete Institute. Manual for the Evaluation and Repair of Precast,Prestressed Concrete Bridge Products, First Edition, MNL-137-06-E. Chicago, IL:Precast/PrestressedConcreteInstitute,1999.

7. Arancibia,M.D. and Okumus, P., Causes of Excessive Detensioning Stresses in the NortheastExtremeTee(NEXT)Beams,PCIJournal,Precast/PrestressedConcreteInstitute,May-June2017

AASHTO

8. “LRFDBridgeDesignSpecifications,SeventhEdition,AmericanAssociationofStateHighwayandTransportationOfficials,Washington,D.C.,2014

9. LRFDBridgeConstructionSpecifications, ThirdEdition,AmericanAssociationof StateHighwayandTransportationOfficials,Washington,D.C.,2002

10. AASHTO T197, "Standard Methods of Test for Time of Setting of Concrete Mixtures byPenetration Resistance, “American Association of State Highway and Transportation Officials,Washington,D.C.

11. AASHTOT24, “StandardMethodsofObtainingandTestingDrilledCoresandSawedBeamsofConcrete”, American Association of State Highway and Transportation Officials, Washington,D.C.

12. AASHTO Highway Subcommittee on Construction, "Implementation Manual for QualityAssurance, (AASHTO IMQA), American Association of State Highway and TransportationOfficials,Washington,D.C.,1996

13. AASHTO Highway Subcommittee on Construction, "Quality Assurance Guide Specifications,(AASHTO QA)”, American Association of State Highway and Transportation Officials,Washington,D.C.,1996

ACI

87

14. ACICommittee211,"StandardPracticeforSelectingProportionsforNormal,HeavyweightandMassConcrete",(ACI211.1-91)AmericanConcreteInstitute,FarmingtonHills,MI,1991

15. ACICommittee212,“ChemicalAdmixturesforConcrete",(ACI212.3R-91),AmericanConcreteInstitute,FarmingtonHills,MI,1991

16. ACICommittee221,"GuidetoUseofNormalWeightAggregates inConcrete", (ACI-221R-89),AmericanConcreteInstitute,FarmingtonHills,MI,1989

17. ACI Committee 224, “Control of Cracking in Concrete Structures”, (ACI 224R-90), AmericanConcreteInstitute,FarmingtonHills,MI,1990

18. ACICommittee503,“UseofEpoxyCompoundswithConcrete",(ACI503R-93,reapproved1998),AmericanConcreteInstitute,FarmingtonHills,MI,1998

19. ACI Committee 503, "Guide for the Selection of Polymer Admixtures with Concrete”, (ACI503.5R-92,reapproved1997),AmericanConcreteInstitute,FarmingtonHills,Ml,1997

20. ACI Committee 503, “Guide for the Application of Epoxy and Latex Adhesives for BondingFreshly Mixed and Hardened Concrete”, (ACI 503.6R-97), American Concrete Institute,FarmingtonHills,MI,1997

Documents

2018 01 17 PCINE Guidelines for Resolution of Non ... · Duane Carpenter New York State DOT, Albany, NY Michael Twiss New York State DOT, Albany, NY ... materials, and repairs of