concrete Concrete Repairs Performance in Service and Current Practice IHS BRE 2010.pdf

concrete Concrete Repairs Performance in Service and Current Practice IHS BRE 2010.pdf

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ConCreterepairsperformanceinserviceandcurrentpracticeGptillyandJJacobsConCreterepairsperformanCeinserviCeandCurrentpraCtiCeItisestimatedthataround50%ofEuropesannualconstructionbudgetispresentlyspentontherefurbishmentandrepairofexistingstructures.Thisreportistheculminationofawide-rangingsurveyintotheperformanceofbothcurrentEuropeanconcreterepairtechniquesandinspectionpractices,andcurrentresearchprojects.Itassessesthecasehistoriesgatheredfromacrossthesector,includingfromownersofconcretestructures,repairersandresearchinstitutes,andpresentsitsfindingsusingcharts,graphs,tablesandphotographs.Areviewoftheproblemsofconcretedurability,currentissuesofsustainability,andthedifferingexpectationsofwhatconcreterepairsshouldachieve,provideapracticalintroductiontothesubject.ThesurveywaspartoftheworkcarriedoutbytheCONREPNETnetwork,madeupofEuropeanresearchandrepresentativebodiessponsoredbytheEuropeanCommission.relatedtitlesfromihsbrepressaChievinGdurablerepairedConCretestruCturesEP77,2007ConCretestruCturesinfire:

performanCe,desiGnandanalysisBR490,2007IHSBREPress,WilloughbyRoadBracknell,BerkshireRG128FBEP79ConCreterepairsperformanceinserviceandcurrentpracticeGptillyandJJacobsihsbrepressConrepnet1coverv1.indd112/11/200711:

18:

53ConcreterepairsPerformanceinserviceandcurrentpracticeCONREPNETThematicnetworkonperformance-basedremediationofreinforcedconcretestructuresGPTilly,Gifford&PartnersLtdJJacobs,BelgianBuildingResearchInstituteCONREPNETPartners:

Prelims12/11/072:

32PMPage1DetailsofallpublicationsareavailablefromIHSBREPressWebsite:

orIHSBREPressWilloughbyRoadBracknellRG128FB,UkTel:

01344328038Fax:

01344328005Email:

Requeststocopyanypartofthispublicationshouldbemadetothepublisher:

IHSBREPressGarston,WatfordWD259XX,UKTel:

01923664761Fax:

01923662477Email:

EP79CONREPNET2007Firstpublished2007ISBN:

978-1-86081-974-2KeywordsConcretestructures,EN1504,maintenance,management,performance-basedintervention,protection,repair,remediation,sustainableassets,through-lifecareThecompanionpublicationAchievingdurablerepairedconcretestructuresisavailablethroughIHSBREPress（orderref.EP77）.Bothpublicationscanbepurchasedasaset（orderref.EP81）.Forfurtherdetailspleasevisitwww.ihsbrepressPrelims23/11/073:

20PMPageiiiiiExecutivesummaryviiCONREPNETpartnerorganisationsviiiAcknowledgementsixAbbreviationsxChapter1Introduction1Chapter2Expectationsofrepairs3Chapter3Performanceofrepairsinpractice53.1Background53.2Causesofdeterioration73.3Typesofrepair83.4Performanceofrepairs103.4.1Inspection103.4.2Classificationofperformances103.4.3Overallrepairperformances103.4.4Overallrepairperformances（byrepairtype）103.4.5Cathodicprotection（CP）113.4.6Typesofdeterioration123.4.7Repairsincombination123.4.8Modesofrepairfailure133.5Causesofrepairfailures143.5.1Incorrectdiagnosis143.5.2Incorrectdesign143.5.3Poorworkmanship153.5.4Incorrectrepairmaterial15Chapter4Currentrepairpractice174.1Background173.2Inspection174.3Repairmethods184.4Qualitycontrol194.5Comparisonwithearlierrepairpractice204.5.1Relativeuseofthedifferentmethodsofrepair204.5.2Typesofpatchrepair204.5.3Coatings214.6Inspectionstrategy214.6.1Methodologyofinspection224.6.2Post-tensionedstructures25ContentsPrelims12/11/072:

32PMPageiiiivConcreterepairs:

PerformanceinserviceandcurrentpracticeChapter5Currentresearch275.1Sizesofresearchprojects275.2Researchtopics285.3Outcomeofresearchprojects285.3.1Improveddurability295.3.2Performance-basedrepair30Chapter6EuropeanStandards316.1Thecurrentposition316.2Applicationtoperformance-basedrepair32References33Appendices35AppendixIConcreteRepairHistoryQuestionnaire36AppendixIIConcreteRepairMethodsQuestionnaire38AppendixIIIConcreteRepairEvaluationMethodsQuestionnaire40AppendixIVConcreteRepairResearchQuestionnaire42AppendixVRelatedresearchprojects44Prelims12/11/072:

32PMPageivFiguresFigure3.1Distributionofrespondents6Figure3.2Distributionofenvironments6Figure3.3Distributionofcase-historiesbystructure6Figure3.4Agesofstructures7Figure3.5Primarycausesoforiginaldeterioration8Figure3.6Agesofstructureswhenrepaired8Figure3.7Relativeincidencesofdifferenttypesofrepair9Figure3.8Relativeusesofdifferenttypesofcoatings9Figure3.9Performancesinrelationtoageofrepairs10Figure3.10Patchrepairafterfiveyears,showingsignsofincipientanodebehaviourduetonon-removalofchloridecontaminatedmaterial10Figure3.11Performancesofpatches12Figure3.12Performancesofpatchrepairstocorrosion13Figure3.13Modesoffailurealltypesofrepair13Figure3.14FailureofpolymermortarpatchesandsprayedpolymercoatingsappliedtoanAARaffectedbridge14Figure3.15Failureofpolymermortarpatchesandpolymercoatingappliedtoabridgeaffectedbycorrosion14Figure3.16Reportedcausesoffailures15Figure3.17Aestheticdeteriorationofcement-basedcoatingrepair15Figure3.18Influenceofenvironmentonperformancealltypesofrepair16Figure4.1Useofrepairtechniques18Figure4.2Acceptanceratingsofrepairproductsinthemarket19Figure4.3Acceptanceratingsoftherepaircompanies19Figure4.4Comparisonbetweenpastandcurrentusageofrepairmethods20Figure4.5Comparativeuseofcement-basedandpolymer-basedmortarsinpatches21Figure4.6Comparativeuseofbarrierandhydrophobiccoatings21Figure4.7Performancesofrepairs22Figure4.8Levelsofdetectabilityofthedeteriorationofarepair22Figure4.9Pull-offtesttomeasureadhesionofcoatingsandpatches24Figure4.10Corrosionprobesfittedtoreinforcementpriortorepairconcretebeingplaced24Figure4.11Locationofreinforcementbars25Figure4.12Measurementofcrackwidths25Figure4.13Detectionofcarbonation25Figure4.14Measurementofelectrodepotential25Figure5.1Distributionofrespondentstoresearchquestionnaire27Figure5.2Distributionofresearchtopics28ContentsvPrelims12/11/072:

32PMPagevTablesTable3.1SuccessfulCPinstallations12Table4.1Relativeusageofinspectiontechniques17Table4.2Useofthecommonmethodsofrepair18Table4.3ExamplesofNDTtoaidacceptanceofrepairs24Table4.4Continuousmonitoring24Table5.1Numberofparticipantsinresearchprojects27Table5.2Distributionofresearchtopicsandfunding28Table5.3Distributionofresearchprojects28Table5.4Researchpreferencesofrespondents29Table5.5Outcomeofongoingandcompletedresearchprojects29Table5.6Researchproblemsidentifiedfromcase-histories29Table6.1EuropeanStandardsrelatedtoconcreterepairproductsandsystems31viConcreterepairs:

PerformanceinserviceandcurrentpracticePrelims12/11/072:

32PMPageviIthasbeenestimatedthatsome50%ofEuropesannualconstructionbudgetisspentonrefurbishmentandrepairofexistingstructures.Thisfigureisexpectedtoincreaseasthemajorpopulationofconcretestructuresbuiltinthe1960sand1970s,whichformakeypartofEuropesinfrastructure,starttorequirefurtherrepairandrefurbishment.However,limitedavailableresourcesneedtobeappliedwithgreaterefficiencyandownersofbuildingsandinfrastructurenowrequiregreatercertaintyintheperformanceoftheirconcretestructuresinordertomanagetheirassetsmoreeffectively.Thishasgeneratedarequirementforindustrytodelivermoredurablerepairstoconcretestructures.Tohelpaddresstheseissues,athematicnetworkontheperformance-basedrepairofreinforcedconcretestructureswasestablishedin2003,knownasCONREPNET.TheobjectofthisEU-fundednetworkistoimprovethedurabilityofconcreterepairsthroughperformance-basedrehabilitation.Tothisend,informationaboutconcretedurabilityandrepairissueshasbeencollectedfromindustryandresearchers.Problemsandbarrierstoachievingdurableconcreterepairshavebeenidentifiedandcontemporaryindustrypracticeshavebeeninvestigated.Thisreportisconcernedwithsectionsoftheprojectthatdealwithperformancesofrepairsinpractice,currentpracticeandresearch.Performanceinpracticehasbeenassessedthroughcase-historiesobtainedfrommembersofthenetworkandothers.Some230case-historieswereobtainedforconcretestructuresupto150yearsoldbutmostly20to50yearsold.Themostcommontypeofdeteriorationreportedwascorrosionofthesteelreinforcement,whichoccurredin55%ofthecases.Performancesofrepairsaredisappointing;20%failedinfiveyears,55%failedin10yearsand90%failedin25years.Thelongestrepairlifewas52years.Themostsuccessfulrepairswereschemesinvolvingrestorationofstrengthandcrackinjection.Patcheswereappliedin60%oftherepairsandwere30%successfulwhenappliedsoloand50%successfulwhenappliedincombinationwithacoating.Causesofrepairfailureswereascribedtoincorrectdiagnosis,incorrectdesignofrepair,poorworkmanship,useofincorrectmaterialsandotherfactorssuchasextremeweatherconditionsduringtherepairwork.Mostoftherepairprojectsreportedinthecasehistorieswerecarriedoutintheperiodfrom1960to1990,usingpracticescurrentatthetime.Asurveyofcurrentrepairpractice（2003）indicatedthattherehasbeenlittlechangesincethemethodsofrepaircontinuetobebroadlysimilar.Patchingisbecominglesscommonaselectro-chemicaltechniquesandpolymermortarsbecomemoreprevalent.Inspectionisregardedascriticaltotherepairprocessbutsomesmallrepairworksforprivateownerswerereportedasstartingwithoutanyinspection.Themostcommonmethodsofnon-destructivetestingweremeasurementsofdepthofcover,carbonationandchloridecontent.Around25%ofrepairandinspectionworkissubcontracted.Atotalof138researchprojectsweresurveyed（66obtainedviaquestionnairesand72viatheoffic