Concrete Repair According to the new European Standard EN
1504Prof. Dr.-Ing. M. Raupach,RWTH Aachen,
ibacABSTRACT:GreatefforthasbeenmadetoworkoutaEuropeanStandardonprotectionandrepairofconcretestructures.
After more than ten years of intensive discussions within different
working groups the series of standards isnow more or less
finalised. Actually the European Countries are preparing to replace
the existing national
standardsandrecommendationsbythenewEuropeanStandardEN1504.Itcanbeassumedthatthisstandardwillhaveasignificant
impact also to the Non-European countries.1
INTRODUCTIONRepairandrestorationofconcretestructureshasbecomeanimportantmarket.Asanexamplethecostsfor
the maintenance of bridges are higher than 1 billion $per year. The
total costs for maintenance of all types
ofbuildingscanbeassumedtobehigherthanabout20billion$peryear.Asignificantpartofthiscostsarespentonrepairandprotectionofconcretestructures.On
the contrary to the amount of work spent on
buildingnewstructures,themarketofrepairandprotectionhasgrownconsiderablyastheageoftheexistinginfrastructureisincreasing.Theextensivedevelopmentofnewmethodsandmaterialsfortherepairandprotectionofconcretestructureshasledtotheneedofstandards
for such works and
products.Table1showsthestructureofthenewEN1504,consisting of 10
main standards and about 65
standardsfortestmethods.Asshownintable1theseriesofstandards is
focused on parts 2 to 7, which are the basisfor CE marking of the
different products and systems tobe used for protection and repair
of concrete
structures.However,part9ofEN1504isnotlessimportant,describingtheprinciplesfortheuseoftheproducts,which
will be explained in the following sections. Part
1givesdefinitions,part8regulatesthequalitycontroloftheproductsandpart10givesageneralguidelineforsiteapplicationandqualitycontroloftheworks.ToallowCEmarkingoftheproductsabout65standardsdescribing
test methods for the different properties of
theproductshadtobeprepared.Thesestandardsensurethat testing of the
products will be according to the
samestandardsforallproductsforprotectionandrepairofconcrete
structures used in Europe.Table 1:Structure of EN 1504EN
1504-9Principles for the use of the productsEN 1504-2 to 7: Test
methods(about 65 standards)EN 13 396(chloride ingress)EN 14
497(filtration stability)...Products- surface protection- repair
mortars- bonding materials- injection materials- anchoring products
- coatings for steelEN 1504-10Site applicationand quality controlof
the worksEN 1504-1DefinitionsEN 1504-8 Quality control of the
productsFuther test methods2 PHASES OF REPAIR PROJECTSThe phases of
repair projects follow a logical
sequence,whichisdominatedbyengineeringaspects.Table2givesageneralschemeaccordingtofigureB1withinannexBofEN1504-9.Thisfigureshowsthewell-knownelementsasassessment,planning,designandqualitycontrol.However,thesystematicsofgeneralplanningisquitenewrelatedtotheactuallyexistingrecommendationsandstandards.Itconsistsofahierarchyoflevels,namelyoptions,principlesandmethods,whicharedescribedinmoredetailinsection4.Table
2: The phases of repair projectsManagement of the StructureCondi ti
ons andhistory ofstructureClause 8 ofEN
1504-9DocumentationCommissions for maintenanceProcess
ofAssessmentDefects and their classifica-tion and
causesGeneralPlanningOptionsPrinciplesMethodsClauses 5 and 6 ofEN
1504-9Design ofRepair WorkDefi ni ti ons of theintended use
ofproductsEN 1504-2 toEN 1504-7 andclause 7 and annex A ofEN
1504-9Requirements- substrate- products- work- specifications-
drawingsRepair WorkChoi ce and useof products andequipmentClause 9
of EN 1504-9 andENV 1504-10Tests of qualitycontrolHealth and
safetyAcceptance ofRepair WorkRemedial worksDocumentationAcceptance
testingBasic considerations and actionsParts of the EN 1504 series
and clauses of EN 1504-94.3 ofEN 1504-93 PROCESS OF
ASSESSMENTTable3showscommoncausesofdefectsaccordingtofigure 1 of EN
1504-9. With respect to later planning
ofrepair,generallyitshouldbedistinguishedbetweendefects in concrete
and defects caused by reinforcementcorrosion. The purpose of the
main assessment isto identify the cause or causes of defectsto
establish the extent of
defectstoestablishwherethedefectscanbeexpectedtospreadtopartsofthestructure,thatareatpresentunaffectedtoassesstheeffectofdefectsonstructuralsafetyandtoidentifyalllocations,whereprotectionorrepairmay
be needed.More details on requirements for assessment are given
inEN 1504-9.Table 3: Common causes of
defectsImpactOverloadMovement(e.g.
settlement)ExplosionVibrationMechanicalAlkali-aggregatereactionAggressive
agentse.g. sulphates,softwater, saltsBiological
activitiesChemicalFreeze/thawThermalSaltcrystallizationShrinkageErosionWearPhysicalDefects
in Concrete Reinforcement CorrosionCarbonationStray currentsSodium
ChlorideCalciumChloride Other contaminantsSodium ChlorideCorrosive
contaminantsAt mixingFrom externalenvironmentFigure 1: Example for
a damage of the
concreteFigure2:Exampleforreinforcementcorrosioncausedbycarbonation
of the
concreteFigure3:Exampleforreinforcementcorrosioncausedbychloride
ingress4 OPTIONS,PRINCIPLESANDMETHODSFOR PROTECTION AND
REPAIRAsalreadymentioned,therulesfortheuseofproductsandsystemsforprotectionandrepairofconcretestructuresisbasedonahierarchyofdifferentlevels,namelyoptions,principlesandmethods.AccordingtoEN1504-9thefollowingoptionsshallbetakenintoaccountindecidingtheappropriateactiontomeetthefuture
requirements for the life of the structures:(a)Do nothing for a
certain
time(b)Re-analysisofstructuralcapacity,possiblyleadingtodowngradingofthefunctionoftheconcretestructure.(c)Preventionorreductionoffurtherdeterioration,without
improvement of the concrete
structure.(d)Improvement,strengtheningorrefurbishmentofallor parts
of the concrete
structure.(e)Reconstructionofpartoralloftheconcretestructure
and(f)Demolition of all or part of the concrete structure.For
protection and repair, different principles have beendefined,
separately for repair and protection of
damagestotheconcreteanddamagesinducedbyreinforcementcorrosion.Tables4and5showthe6principlesforprotection
and repair of concrete and the 5 principles
topreventdamagesduetoreinforcementcorrosionrespectively. Theses
principles are based on the
RILEMTechnicalRecommendation124-SRCStrategiesforrepairofconcretestructuresdamagedbysteelcorrosion.Toprotectorrepairaconcretestructureaccordingtotheprinciplesdifferentmethodsareavailable.Figures8-15inannexAofthispapershowthe
methods and short descriptions for the 11
principles.Altogether37methodsaredescribedwithinEN1504-9.NotallofthemarecoveredbytheEN1504series,butbyotherstandards,andsomeofthemareactuallynot
standardised, but expected to be regulated in
future.Thesystemofoptions,principlesandmethodsisthebasisfortheselectionofproductsbythedesigner.Theprocessofplanningandselectionofproductsisdescribed
within the next section.Table 4: Principles for repair and
protection for damages of theconcretePrinciple No.Principle 1
[PI]Principle 2 [MC]Principle 3 [CR]Principle 4 [SS]Principle 5
[PR]Principle 6 [RC]Principle and its definitionProtection against
ingressMoisture ControlConcrete RestorationStructural
StrengtheningPhysical resistanceResistance to
chemicalsTable5:PrinciplesforprotectionagainstreinforcementcorrosionPrinciple
No.Principle 7 [RP]Principle 8 [IR]Principle 9 [CC]Principle 10
[CP]Principle 11 [CA]Principle and its definitionPreserving or
Restoring PassivityIncreasing ResistivityCathodic ControlCathodic
ProtectionControl of Anodic
areasFigure4:Exampleforsurfacecoatingaccordingtomethod1.2(Table 8),
2.2 (Table 9), 6.1 (Table 12) or 8.1 (Table 14)Figure
5:Exampleforhydrophobicimpregnationaccordingtomethod 2.1 (Table
9)Figure 6:Exampleforapplyingmortarbyhandaccordingtomethod 3.1
(Table 10)Figure 7: Example for recasting with concrete according
tomethod 3.2 (Table 10)Figure 8: Example for plate bonding
according to method 4.3(Table 11)Figure 9: Example for injection of
cracks according to method4.5 (Table 11)5 PLANNING AND SELECTION
OFPRODUCTSTable 6 shows
thesystematicsofplanningaccordingtoEN1504-9.Asalreadyshownintable2,theplanningstartswiththeassessmentofthestatusofthestructure.Thefollowingpointsareselectionofoptions(repairstrategy),
repair principles and repair method, as
definedintheprevioussection.Basedonthisselectionschemetherepairmaterialscanbechosen.EN1504-9definesperformancecharacteristicsforeveryrepairmethod,separately
for all
intendedusesandforcertainintendeduses.Thedesignerselectstheperformancecharacteristicsbasedontherequirementsofthespecialrepair
project and the selected repair methods. Table 7gives 3 examples of
certain cases, with the
performancecharacteristicsrelevantfortheselectedrepairmethods.EN
1504-2 to 7 contain the performance
characteristicsoftheproductstogetherwiththecorrespondingtestmethods.Inthiswaytheproductsareselectedindi-vidually
for the demands of the special case of repair
orprotectionofaconcretestructure.Asaresult,theproducts are
described by a list of required
performancecharacteristicsinsteadofsimpleclasses,resultinginahighlevelofflexibility,butalsoresponsibilityofthedesigner.Finally
inspection and maintenance requirements shall bedefined by the
designer.Table 6: Systematics of planning according to EN
1504-9Assessment of the status of the structure (defects
...)Elaboration of the repair strategy (do nothing, repair, ...,
demolition)Definition of the repair principles (e.g. protection
against ingress ...)Selection of the repair method (e. g.
impregnation ...) Definition of the repair materials (strength,
modulus, adhesion, etc.)Definition of inspection and maintance
requirements6 CONCLUSIONS AND
OUTLOOKAnewEuropeanstandardonprotectionandrepairofconcretestructureshasbeenworkedout,basedontheactual
state of knowledge regarding the properties of
theproducts,theprinciplesfortheuseoftheproducts,application and
quality control. Parts 2 to 7 regulate theperformance of the
products and systems for
protectionandrepairofconcretestructureswithrespecttoCEmarking.Theuseoftheproductsisbasedonalogicalsequence
consisting of options (repair strategies), repairprinciples and
repair methods, which are listed in tablesin part 9 of EN 1504.
This scheme ensures that
suitableproductsareselectedbasedontherequirementsofthepractical
case. It is expected that this new series of
stan-dardswillreplacetheexistingnationalstandardsinEurope within
the next 2 or 3 years and that it will alsohave significant impact
for other countries.Table 7: Examples of the application of the
classification system in 3 individual cases according to EN
1504-2No. accordingto Table 1Test methodsdefined inPerformance
characteristicsExample 31.3/5.1Example 21.3/5.1/6.1Example
11.3/2.2EN ISO 5470-1EN12190EN 12617-1EN1062-6EN ISO
7783-2EN1062-31246789121314151820Adhesion after thermal
compatibilityFreeze-thaw cycling with de-icing salt immersion EN
13687-1EN 13687-2EN 13529EN 1062-7EN ISO 6272-1EN 1542EN 13036-4EN
1062-11:2002EN 1062-11:2002Linear shrinkageCompressi ve
strengthAbrasion resistancePermeability to CO2Permeability to water
vapourCapillary absorption and permeability to waterThunder shower
cycling (thermal shock)4.1: Aging 7 days at 70 CResistance to
severe chemical attackCrack bridging abilityImpact
resistanceAdhesion by Pull-off testSlip/Skid resistance4.2
Behaviour after artificial weatheringEXAMPLE 1Coating system for
exposed surfaces, not mechanically or chemically loaded, without
de-icing salt influence acc. to the principles 1 (IP) and 2 (MC),
see Table 1, 1.3 (C) and 2.2 (C).EXAMPLE 2Coating system for
interior surfaces, mechanically and chemically loaded, in acc. and
6 (RC), see Table 1, 1.3 (C), 5.1 (C) and 6.1 (C).to the principles
1 (IP), 5 (PR) EXAMPLE 3Crack bridging coating system for exposed
surfaces mechanically and lowchemically loaded, with de-icing salt
influence in acc. to the principles 1 (IP) and 5 (PR),see Table 1,
1.3 (C) and 5.1
(C).7LITERATURE[1]EN1504-11998-01-00.Productsandsys-temsfortheprotectionandrepairofconcretestructures-Definitions,requirements,qualitycontrolandevaluationofconformity-Part1:Definitions[2]EN1504-22004-10-00.Productsandsys-temsfortheprotectionandrepairofconcretestructures-Definitions,requirements,qualitycontrolandevaluationofconformity-Part2:Surface
protection systems for
concrete[3]DINEN1504-32001-06-00Productsandsystemsfortheprotectionandrepairofconcrete
structures - Definitions,
requirements,qualitycontrolandevaluationofconformity-Part3:Structuralandnon-structuralrepair;GermanversionprEN
1504-3:2001(WITHDRAWN in October
2004)[4]EN1504-42004-11-00.Productsandsys-temsfortheprotectionandrepairofconcretestructures-Definitions,requirements,qualitycontroland
evaluation of conformity - Part 4:Structural bonding[5]prEN 1504-5
2004-04-00. Products and
sys-temsfortheprotectionandrepairofconcretestructures-Definitions,requirements,qualitycontrolandevaluationofconformity-Part5:Concrete
injection[6]prEN 1504-6 2004-05-00. Products and
sys-temsfortheprotectionandrepairofconcretestructures-Definitions,requirements,qualitycontrolandevaluationofconformity-Part6:Anchoring
of reinforcing steel
bar[7]DINEN1504-72005-01-00Productsandsystemsfortheprotectionandrepairofconcrete
structures - Definitions,
requirements,qualitycontrolandevaluationofconformity-Part7:Reinforcementcorrosionprotection;German
version prEN
1504-7:2004[8]EN1504-82004-11-00.Productsandsys-temsfortheprotectionandrepairofconcretestructures-Definitions,requirements,qualitycontrolandevaluationofconformity-Part8:Quality
control and evaluation of conformity[9]ENV 1504-9 1997-07-00.
Products and
sys-temsfortheprotectionandrepairofconcretestructures-Definitions,requirements,qualitycontrolandevaluationofconformity-Part9:General
principles forthe use of products
andsystems[10]EN1504-102003-12-00.Productsandsys-temsfortheprotectionandrepairofconcretestructures-Definitions,Requirements,Qualitycontrol
and evaluation of conformity - Part
10:Siteapplicationofproductsandsystemsandquality control of the
worksANNEX ATables 8-15:Table 8: Principle no. 1Principle
No.Principle 1 [PI]Principle and its definitionProtection against
ingressReducing or preventing theingress of adverse agents,e.g.
water, other liquids,vapour, gas, chemicals andbiological
agents.Methods based on the principle1.11.21.31.41.51.61.7Applying
liquid products whichpenetrate the concrete and blockthe pore
system.ImpregnationSurface coating with and withoutcrack bridging
abilityLocally bandaged cracks 1)Filling cracksTransferring cracks
into joints 1)Erecting external panels 1) 2)Applying membranes 1)1)
These methods may make use of products and systems not covered by
the EN 1504 series2)Inclusion of methods in this Prestandard does
not imply their approvalTable 9: Principle no. 21) These methods
may make use of products and systems not covered by the EN 1504
series2)Inclusion of methods in this Prestandard does not imply
their approvalPrinciple No. Principle and its definition Methods
based on the principlePrinciple 2 [MC] Moisture ControlAdjusting
and maintainingthe moisture content inthe concrete within
aspecified range of values.2. 12. 22. 32. 4Hydrophobic
impregnationSurface coatingSheltering or
overcladdingElectrochemical treatment Applying a potential
differenceacross parts of the concrete toassist or resist the
passage ofwater through the concrete.(Not for reinforced
concretewithout assessment of therisk of inducing corrosion).1)
2)1) 2)Table 10: Principle no. 3Principle No.Principle 3
[CR]Principle and its definitionConcrete RestorationRestoring the
original concreteof an element of the structureto the originally
specified shapeand function.Restoring the concrete structureby
replacing part of it.Methods based on the
principle3.13.23.33.4Applying mortar by handRecasting with
concreteSpraying concrete or mortarReplacing elementsTable 11:
Principle no. 41) These methods may make use of products and
systems not covered by the EN 1504 seriesPrinciple No.Principle and
itsdefinitionMethods based on the principlePrinciple 4 [SS]
Structural StrengtheningIncreasing or restoring thestructural load
bearingcapacity of an elementof the concrete
structure.4.14.24.34.44.54.64.7Adding or replacing embedded
orexternal reinforcing steel barsInstalling bonded rebars
inpreformed or drilled holes in the concretePlate bondingAdding
mortar or concreteInjecting cracks, voids orintersticesFilling
cracks, voids or intersticesPrestressing - (post tensioning)
1)Table 12: Principle no. 5-6Principle 5 [PR]Principle 6
[RC]Physical resistanceResistance to chemicalsIncreasing resistance
tophysical or mechanical attack.Increasing resistance of the
concrete surface to deteriora-tions by chemical attack.5. 16. 16.
25. 2Overlays or coatingsOverlays or
coatingsImpregnationsImpregnationPrinciple No. Principle and its
definition Methods based on the principleTable 13: Principle no.
71) These methods may make use of products and systems not covered
by the EN 1504 seriesPrinciple No.Principle 7 [RP]Principle and
itsdefinitionPreserving or RestoringPassivityCreating chemical
condi-tions in which the surfaceof the reinforcement ismaintained
in or isreturned to a passivecondition.Some examples of methods
based on the principle7.17.27.37.47.5Increasing cover to
reinforcementwith additional cementitiousmortar or
concreteReplacing contaminated orcarbonated concreteElectrochemical
realkalisation ofcarbonated concrete 1)Realkalisation of
carbonatedconcrete by diffusionElectrochemical chlorideextraction
1)Table 14: Principle no. 8-92)Inclusion of methods in this
Prestandard does not imply their approvalPrinciple and
itsdefinitionSome examples of methods based on the
principlePrinciple No.Principle 8 [IR]Principle 9 [CC]Increasing
ResistivityCathodic ControlIncreasing the electricalresistivity of
the concrete.Creati ng condi ti ons i nwhich potentiallycathodic
areas ofreinforcement areunable to drive ananodic
reaction.8.19.1Limiting moisture content by surface
treatments,coatings or shelteringLimiting oxygen content(at the
cathode) bysaturation or surfacecoating 2)Table 15: Principle no.
10-111) These methods may make use of products and systems not
covered by the EN 1504 series2)Inclusion of methods in this
Prestandard does not imply their approvalPrinciple and
itsdefinitionSome examples of methodsbased on the
principlePrinciple No.Principle 10 [CP]Principle 11 [CA]Cathodic
ProtectionControl of Anodic areasCreating conditions
inwhichpotentiallyanodic areas ofreinforcement areunable to take
partin the corrosionreaction10.111.111.211.3Applying electrical
potential 1)Painting reinforcement withcoatings containing
activepigmentsPainting reinforcement withbarrier coatingsApplying
inhibitors to theconcrete 1) 2)
