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Cons
truct
ion
Technology and Concepts Repair and Protectionof Reinforced Concrete
2
Corrosion Management in Reinforced Concrete Structures
The successful repair and protection of concrete structures whichhave been damaged or which have deteriorated requires professionalassessment, then design, supervision and execution of a technicallycorrect strategy - according to the forthcoming European Standardbeing developed by CEN/TC 104.
This brochure is intended to give guidance on the correct procedureand on the appropriate products and systems for the selectedstrategy. The key stages in the process are:-
Assessment Survey of theCondition of the Structure
Diagnosis of the Cause of Deterioration
Determine the Repair andProtection Objectives
Select the AppropriateRepair and Protection
Strategy
Definition of the futureMaintenance Requirements
and Procedures
The key stages in theprocess are:-
Assessment Survey of the Condition of theStructure
The assessment of the conditionof a damaged or deterioratedreinforced concrete structureshould only be made byqualified and experiencedpeople.
The process of assessment willalways include the followingaspects:-
■ The current condition of the structure including visible, non visible and potentialdefects.
■ Review of the past, current and future exposure.
Diagnosis of the Cause of Deterioration
Following review of the originaldesign, construction methodsand programme, and theassessment survey Identify the“root causes” of damage:-
■ Identify mechanical, chemical and physical damage to theconcrete.
■ Identify concrete damage due to reinforcement corrosion.
3
Determine the Repairand ProtectionObjectives
With most damaged ordeteriorated structures the Owner has a number of optionswhich will effectively decide theappropriate repair andprotection strategy to meet thefuture requirements of thestructure. The options include:-
■ Do nothing.
■ Downgrade the structure orits capacity.
■ Prevent or reduce furtherdamage without repair.
■ Improve, refurbish orstrengthen all or part of the structure.
■ Demolition.
Select the appropriateRepair and ProtectionStrategy
It is necessary to clarify theOwner’s requirements andinstructions in relation to:-■ The required durability,
requirements and performance.
■ Intended design life.
■ How loads will be carriedbefore, during and after therepair.
■ The possibility for futurerepair works includingaccess and maintenance.
■ Costs of the alternativesolutions.
■ The consequences andlikelihood of structural failure.
■ The consequences andlikelihood of partial failure(falling concrete, wateringress etc).
And Environmentally:-■ The need for protection from
sun, rain, frost, wind, saltand/or other pollutantsduring the works.
■ The environmental impact orrestrictions on the works inprogress particularly thenoise and the time taken tocarry out the work.
■ The likely environmental/aesthetic impact of theimproved/ reducedappearance of alternative solutions.
Definition of the futureMaintenanceRequirements andProcedures
■ What is the mode and result of the selected materials deterioration ie. chalking, embrittlement, discolouration,delamination?
■ What surface preparation andaccess systems will eventuallybe required and when?
■ Who is responsible and how will it be financed?
NO NOISE
LIMITED HOURS
4
Assessment Surveyand Diagnosis of Damage
Reinforcement corrosion following reductionof the passivating concrete alkalinity by car-bonation.
Reinforcement corrosion showing as rust staining from cracks after galvanised steelrailings were fixed into the parapet.
The damaging effects of steel corrosion accel-erated by chloride ingress from deicing salts.
CONCRETE DAMAGE DUE TO REINFORCEMENT CORROSION
CARBONATION STRAY/ ELECTRICALCURRENT
CORROSIVE CONTAMINANTSeg CHLORIDES
■ Carbon Dioxide (CO2) inthe atmosphere reactingwithCalcium Hydroxide inthe concrete pore liquid.
■ CO2 + Ca(OH)2➔ CaCO3 + H2O
■ Soluble and pH 12-13➔
Almost insoluble and pH 9
■ Steel Passivated➔ SteelUnprotected
■ Metals of differentelectropotential areconnected to each other inthe concrete and corrosionoccurs.
■ Also corrosion can be dueto stray electrical currentsfromtransmissionnetworks.
■ Chlorides accelerate thecorrosion processhowever originally caused.
■ At above 0.2-0.4% they breakdown the passive oxide.
■ Chlorides can be from marineexposure or deicing salts.
■ Their use to accelerateconcrete setting at lowtemperatures is now mostlybanned in reinforced concrete.
Cracking caused by incorrect handling or fixing of precast panels.
Chemical attack (and subsequent reinforcement corrosion) on a factory roof. Freeze thaw effect on a parking structure.
CONCRETE, DAMAGE AND DEFECTS
MECHANICAL CHEMICAL PHYSICAL
5
■ Impact, Vibration andExplosion
■ Abrasion and Wear
■ Overloading
■ Alkali AggregateReaction
■ Chemical Exposure
■ Bacterial Action
■ Thermal Movement
■ Freeze Thaw Action
■ Efflorescence/Leaching
■ Salt Crystal Expansion
■ Erosion
6
Determine the Objectives andSelect the Appropriate Strategy
Provide Additional Concrete Cover
Advantages: ■ The old traditional approach.
Disadvantages: ■ Very expensive if correctly
applied over all of the concrete surface.
■ Has no effect on furtheraggressive influence ingress.
■ Provides no protection againstlatent damages.
■ Very poor appearance.
Overcladding and Insulation
Advantages: ■ Greatly improves appearance.
■ Provides the additional benefit of insulation.
■ Provides a long term solution.
Disadvantages: ■ Very expensive.
■ Can hide latent defects.
■ Extended contract period.
Conventional Repair and Protection
Advantages: ■ Meets existing national standards
(DIN/BBA/SIS/NF etc).
■ Proven performance (over 20years with Sika systems).
■ Provides some protection againstlatent carbonation damages.
■ Cost effective.
Disadvantages: ■ No protection against latent
chloride damage.
■ Requires extensive concretebreak out.
■ Considerable noise, vibrationand dust.
Apply Cathodic Protection
Advantages: ■ The only way to completely stop
steel corrosion.
■ Permanent solution (with fullrepairs and monitoring).
Disadvantages: ■ Ongoing cost to maintain.
■ Many structures not suitable(access / non continuousreinforcement / prestressingsteel etc).
Having fully considered theiroptions owners normally face having to “Improve, refurbish or strengthen all or part of the Structure”:-■ For structural strengthening
requirements refer to SikaTechnical Services for full details of the innovative SikaCarbodur structural strengthening system.
■ For concrete structures there are now alternative solutions proposed for improvement and refurbishment that are considered as corrosion management, these include:-
Realkalisation or Desalination
Advantages:■ Based on reversing the
principles of Cathodic protection.
■ Limited concrete removal.
■ No ongoing maintenance (except protective coatings).
Disadvantages: ■ Very high installation cost.
■ Not all structures are suitable (asCathodic Protection).
■ Where there is potential forASR/AAR.
■ Not environment friendly(caustic waste disposal).
7
Concrete Repair and Protection with Corrosion Inhibitors
Advantages: ■ All the advantages of conventional concrete repair
and protection.
■ Greatly reduced concrete break out.
■ Greatly reduced noise vibration and dust.
■ Reduced contract periods.
■ Provides protection against residual chlorides andagainst incipient anode formation.
■ Extremely cost effective.
■ Most structures suitable
■ No ongoing maintenance (except refresher topcoatings after 10-15 years).
Disadvantages: ■ Not proven on prestressed structures (at this time).
System Positioning withSika FerroGard®-903 Corrosion Inhibitor
Sika FerroGard® -903 In New Construction.
Sika FerroGard®-903 Protection before Visible Damage.
Sika FerroGard®-903 as part of a CompleteRepair and Protection Strategy after Visible
Concrete Damage.
average concrete quality afterapplication of Sika FerroGard® -903
average concrete quality without Sika FerroGard®
Service life
Visible damage
Limit of service life
years
Dev
elo
pm
ent
of
corr
osi
on
y = rate of corrosion
y/2 = rateof corrosion
onset of corrosion onset of corrosion
Extension of service life
New start after Sika FerroGard® -903 application
average concrete qualitywithout Sika® FerroGard®
Service life
Visible damage
Limit of service life
years
Dev
elo
pm
ent
of
corr
osi
on
y = rateof corrosion
ny = rateof corrosion
New start after repair
Extension of service life
onset of corrosion onset of corrosion
average concrete quality withconcrete repair and protection including applicationof Sika FerroGard® -903
average concrete qualitywith Sika FerroGard® -903
average concrete qualitywithout Sika FerroGard®
Doubling of the service lifeService life
Visible damage
Limit of service life
years
Dev
elo
pm
ent
of
corr
osi
on
y = rateof corrosion
y/2 = rateof corrosion
onset of corrosion onset of corrosion
Sika® ®®
Technology
Ferro Gard®
8
The Sika® Principles of Concrete Repair & Protection
Protecting exposed reinforcement
Remove damaged concrete and prepare
exposed steel
Replacing damaged concrete
SikaTop®-110 Armatec EpoCem®
■ Protects reinforcement in a highly alkalinecementitious environment
■ Can be applied on dampsurfaces
■ Increases barrier tochlorides and carbonation
■ Steel reinforcement primer and Bonding Bridge
■ Fully complies with loadtransfer requirements
SikaCem® Gunite Mortars
■ Ideal for use with Aliva drysprayed concrete equipment
■ Tested for application tostructures subject tovibration under load
■ Tested for use with mostcathodic protection systems
SikaTop® Repair Mortars
■ Two component prebatchedpolymer modified repair mortars
■ Lower modulus for increased durability
Sika MonoTop® - 610
■ One component steel reinforcement primer and bonding bridge
SikaMonoTop® Mortars
■ One component polymer modified repair mortars
■ Suitable for hand and wet spray machine application
Select the Appropriate Sika System
9
Levelling the profile and filling
surface pores
Protecting against the development of latent
damage
Sealing and Coating - preventing the ingress of
aggressive influences
Hydrophobic Impregnations
Anti-Carbonation Coatings
SikaTop® Levelling Mortars coarse/fine
■ Use to fill surface defectsto ensure continuousprotective coating
■ Produce the desiredsurface texture
■ Provides uniform substrate
SikaGard® - 680S/-675W
■ Effectively halts carbonation■ Allows each way water
vapour diffusion■ Prevents water and
chloride ingress■ Outstanding colour
retention
SikaGard® - 720 EpoCem®
■ Unique epoxy cementtechnology
■ Integral curing ability
■ Also as a protectivecoating
■ Ideal for levelling andreprofiling afterapplication of SikaFerroGard® -903
Sika FerroGard® -903
■ Penetrates via liquid and vapour diffusion
■ Film forming inhibitor
■ Mixed inhibitor acting onanodic and cathodic sites
■ Blended inhibitorcombining special aminoalcohol and inorganicinhibitors
Sika® ®
Technology
Ferro Gard®
SikaGard® - 700S/-702W
■ Prevents water and chlorideingress
■ Allows each way water vapour diffusion
SikaGard® - 550W Elastic
All the special properties ofSikaGard® 675W/ 680S plus:■ Bridges dynamically
moving cracks even at lowtemperatures
■ Water and solvent basedprimers
Sika MonoTop® LevellingMortars coarse/fine
■ One component levelling and reprofiling mortar
10
The Worldwide Independent Proof Statements
Protecting ExposedReinforcement
Replacing DamagedConcrete
IndependentAssessmentand Approval
■ Bond strength to steeland concrete
■ Corrosion protection
■ Permeability to water
■ Permeability to watervapour
■ Permeability to carbondioxide
■ Bond strength
■ Compressive andflexural strengths
■ Permeability to water
■ Elastic modulus(stiffness)
■ Restrained shrinkage
■ Thermal compatability
■ The Bänziger block for testing repair mortars
■ Direct comparison worldwide■ Application horizontal,
vertical and overhead■ Realistic site dimensions■ Additional lab testing by coring■ Crack free performance
under different conditions
■ System PerformanceThere are functional and performancerequirements which must be met byboth the individual products andcomponents of a system and by thesystem together as a whole.
■ Quality AssuranceIt is necessary for any product orcomponent or system to meet welldefined quality assurance and control
standards in production. This is why Sika produce to ISO Standards at ourfactories throughout the world.
■ Application CriteriaIn addition to its performance in place,it is also essential to define and testthe application properties of productsand systems to ensure that they canactually be applied practically on site,and in the differing conditions that willbe necessary. For example:- SikaMortars must be suitable for differingthicknesses and areas/ volumes ofrepair and applied in as few layers aspossible. SikaGard® coatings musthave adequate thixotropy to obtain thedesired wet and dry film thicknessesin the minimum number of coats, andwith these they must also achieveadequate opacity.
Cer
tif
ied Quality System
IS
O9000/EN 29001
Sika Undertake Extensive Durability Testing
Sika have developed Product Performance Testing
SikaGard® products are test-ed for their performance asanti-carbonation and watervapour diffusable coatings,both when freshly applied,and also after up to 10,000hours accelerated weathering(equivalent to in excess of 15years). Only this can give acomplete picture of the product’s true performance. SikaGard® coatings thereforecontinue to perform long afterother coatings have ceased toprovide effective protection.
■ In the Laboratory
■ Product PerformanceThe specific criteria that Sika use toevaluate all of our products andsystems for Concrete Repair andProtection, are in accordance with therequirements of the draft EuropeanStandard developed by CEN/TC104where appropriate. They include the following:-
11
Protecting Against theDevelopment of Latent Damage
Levelling the profile andfilling surface pores
Sealing and Coating -Preventing the Ingress of
Aggressive Elements
■ Penetration ability
■ Film forming ability
■ Corrosion inhibition
■ Chloride displacement
■ Hydroxide displacement(carbonation induced)
■ Bond strength
■ Permeability to carbondioxide
■ Water permeability andabsorption
Sealing withHydrophobicImpregnations■ Penetration ability
■ Permeability to water
■ Permeability to watervapour
■ Freeze thaw resistance
Anti-CarbonationCoatings■ Bond strength
■ Cross hatchperformance
■ Permeability to carbondioxide
■ Permeability to watervapour
■ U.V. light resistance
■ Alkaline resistance
■ Freeze thaw resistance
■ Fire resistance
■ Cleanability
Crack Bridging Anti-CarbonationCoatingsAs above for Anti-CarbonationCoatings, plus:-
■ Crack bridging ability
● Statically
● Dynamically
● At low temperatures
(-20oC/-20oF)
An International review was undertaken byleading independent Consultants and TestingInstitutes. Major projects repaired and pro-tected with Sika Systems between 1977 and1986 were Inspected and their Durability andPerformance Assessed in 1997.
Qual i t y and Durab i l i t y in Concre te Repa i r and Pro tec t ion6
The Lämershagen bridge A2 motorway, GermanyOriginal Construction: Late 1940’s, Concrete Repair and Protection: 1981-82,Inspection: 1997
The Lämershagen bridge over the A2
motorway near Bielefeld in Germany,
was built before the Second World War
in the form of a reinforced concrete
spandrel-braced arch bridge. It was
predominently destroyed in 1945 and
rebuilt after the War.
Reason for repairs andconcept usedIn the course of time, damage occurred
in the form of concrete spalling over
corroding reinforcing steel. This forced
the Motorway Department to carry out
general repairs in 1981. This was
primarily to prevent falling concrete
causing a hazard to motorway traffic.
Photo 2 shows the typical concrete
damages - spalling over corroding
main steel reinforcement.
Substrate preparation by blast cleaning of
the concrete surfaces was carried out first.
The concrete spalling was then repaired
with Icoment Steel Reinforcement Primer
plus Icoment Repair Mortar. All the
surfaces were then levelled with Icoment
520 Mortar. Finally, the reinforced
concrete structure was given a protective
coating of Icosit Concrete Cosmetic in
grey shade RAL 7032.
The repair and protection works took
place during the winter from October
1981 to January 1982 (photo 3), i.e. at
a t ime of year which should not
normally be chosen in this region
(for repair work of this kind) due to
the largely unfavourable cl imatic
conditions (high humidity and/or very
low temperature).
Visual and technologicalcondition of surface in 1997The reinforced concrete arch bridge
retains a largely homogeneous
appearance from medium range
(photo 1).
On closer examination, however, surface
defects are visible which indicate that the
concrete protection is not completely
intact in some local areas.
Photo 4 shows cracks on the structures
with a “brownish” edging. These cracks
Photo 1: Homogeneous appearance of structure from medium range in 1997.
Photo 2: Concrete spalling over corrodingsteel reinforcement in 1981.
Photo 3: Carrying out repairs in the winter of1981/82.
Photo 4: 1997 Network of wide-meshedcracks with “brownish” edging to the cracks
from pollution/contaminants.
Qua l i t y and Durab i l i t y in Concre te Repa i r and Pro tec t ion
4
The StructuresIn the light of durability problems withconcrete bridges built in the sixties, theDanish Road Authorities organised aninspection and investigation of the rootcauses of the concrete deterioration.The Road Authorities also establisheda Working Group with the objectives ofproviding proposals specifically for therefurbishment of some of the concretestructures with multiple cracks, andthen also making suggestions toimprove their approach to protectingconcrete bridges in general.
The ProblemsOn two major highways - the M60 andM61 - they selected five bridges withcharacteristic cracking and concretedamage.
The Working Group collected all of theoriginal construction data relating tothe bridges and the moisture content ofthe concrete was measured on site.The cracks in the bridges wereidentified as being due to a combinationof initial plastic shrinkage cracking;together with cracks now occurring dueto alkali-silica reaction (ASR). This waspreviously determined by laboratoryanalysis as originating from the use ofreactive aggregates, see photo 2.
The SolutionBased on this information and analysis,the Working Group selected a highperformance coating, Icosit Elastic, foroverall protection of the bridges
specifically against future moistureingress. This material was chosen dueto its excellent properties of waterresistance, flexibility (crack-bridging)and its water vapour diffusionresistance (breathability).
On three of the five selected bridgesthe edge beams and the parapets wereprepared, repaired with Sika mortarsand protected in 1983 with IcositElastic, see photo 3.
The other two of the selected bridgeswere left unprotected to be monitoredas a reference to the efficiency of thetreatment.
THE SIKA® REPAIR ANDPROTECTION SYSTEMThe concrete surface was prepared byblast cleaning and vacuum cleaning toremove any residual dust.
Concrete Bridges in Jutland, DenmarkOriginal Construction: 1960’s, Concrete Repair and Protection: 1983,
Inspection and Assessment: 1988, 1991 and 1994
Photo 3: The Bridge parapet after repair andprotection with crack-bridging Icosit® Elastic (1994).
Photo 2: A close up of typical ASR crackingand damages on the bridge parapet (1983).
Photo 1: One of the selected bridges on the M60/M61 (1997).
41
Qual i t y and Durab i l i t y in Concre te Repa i r and Pro tec t ion
®
The Old Customs House, Oslo, Norway
Original Construction: 1921, Concrete Repair and Protection: 1983,
Inspection and Assessment: 1993 and 1997
The StructureThe Old Customs House, Oslo was
designed in reinforced concrete and
when finished in 1921 was one of the
largest reinforced concrete structures
in the wor ld. I t had a long and
complicated construction period, the
original project was stopped and
delayed three t imes before a
satisfactory solution was found for
the foundations. This was due to the
very heavy weight of the building.
Which was eventually piled down to
the sol id bedrock with more than
1500 driven piles.The Old Customs House had fulfilled
its purpose for 60 years, when
new techniques and logistics made
it obsolete for i ts original use. I t
was therefore determined that
the historic structure should be
refurbished and converted into offices.
In 1980 a consort ium of the Oslo
Inspectorate of Ancient Monuments
and Historic Buildings, Espen
Eskeland AS (architects) and Tor
Andenes (contractor) was established
to carry out the conversion and
refurbishment works.The Original ProblemsThe 1980/81 assessment survey
of the structure revealed concrete
carbonation depths of up to
75mm (3"). In addition to this, the
reinforcement cover was also
deemed to be insufficient in several
places. From 1921 to 1980 no
external repairs nor preventative
maintenance had ever been carried
out on the structure. See photos
2 and 3.
The Sika® SolutionFollowing an extensive and detailed
evaluation of all different systems on
the market, a complete Sika Repair
and Protection System was selected by
the consortium. This decision was as a
result of the good references (already
established by 1980), high technical
competence and well documented
complete systems for concrete repair
and protection.The owner ’s requirements were
effectively stopping the deterioration of
the concrete - providing a durable and
maintenance free structure for the
future. The following procedure and
products were used as the system for
the concrete repair and protection.▲ Where necessary removing all
damaged concrete.
Photo 2: The building facade showing
inadequate concrete cover and spalling
concrete over corroding reinforcement before
repairs in 1981.
Photo 3: Close up of the typical concrete
damages in 1981.
Photo 1: Overview of the repaired and protected structure in 1997.
Qua l i t y and Durab i l i t y in Concre te Repa i r and Pro tec t ion
10
Sudbury House, London, UK
Original Construction: c1972, Concrete Repair and Protection: 1986,
Inspection and Assessment: 1997
Sudbury House is a 25 storey tower
block of 132 housing units, situated in
the centre of Wandsworth in London, it
is surrounded by low-rise shopping
areas, service yards and car parks.
The block was built circa 1972 and
designed on the reinforced concrete
shear wall and slab principle with a
piled, reinforced concrete raft
foundation. All construction above
ground floor level is of insitu lightweight
concrete (Lytag).The ProblemsAreas of spalling concrete first became
noticeable as early as 1981, when a
small scale localised investigation
revealed inadequacies in reinforcement
cover and the beginning of
reinforcement corrosion problems.
Subsequently Wandsworth Borough
Council appointed Mitchell McFarlane
and Partners to undertake a more
comprehensive survey and to
make recommendations for repairs
that should have a 15 year life span to
the first required maintenance. This
report was tabled by the engineers in
early 1984.Their main area of concern was the
poor overall condition of the exposed
lightweight concrete, which owing to
high levels of carbonation and
inadequate concrete cover to
embedded steel reinforcement was
cracked and spalling in many areas.
Extensive micro-cracking was also
evident in the surface of the cement
matrix together with other deficiencies
such as areas of condensation within
the apartments and some areas of
failing joint sealants, leading to water
ingress.
Accurate pre-contract assessment of
the full extent of concrete degradation
was not feasable nor cost effective,
due to the greatly varied nature of the
carbonation even over small areas
from between 5mm and 45mm ( 1/4" to
1 3/4"). However there was a definite
tendency for the carbonation to be
greater on the lower seven floors of the
building. This was eventually attributed
in the main, to the fact that the block
was observed to dry out quickly after
rain on the lower levels, and to remain
wet for long periods on the higher. This
residual moisture provided a
“temporary” barrier to carbonation in
these areas.
Repair SolutionsAfter careful consideration the complete
Icoment system from Sika, was chosen
as the system offering the best
reference credentials, track record and
test data. The availability of a physically
compatible lightweight repair mortar,
Photo 1: Sudbury House in January 1997.
Photo 2: Application of Sika ® Lightweight
Repair Mortar during the 1986 contract.
■ Low temperature dynamic crackbridging testing of coatings
■ Machine application of repair mortars
Spray application for test under livedynamic loading.
Q U A L I T YA N D
DURABILITYI N
CONCRETER E P A I R
A N D
PROTECTION
Q U A L I T YA N D
DURABILITYI N
CONCRETER E P A I R
A N D
PROTECTION
®
■ In the Field
12
International Case Studies
Structure24 Storey Housing Block. Reinforced Concrete Frame with Architectural Precast Concrete Cladding Panels
Problem■ Loading and impact damaged
architectural precast cladding panels(from time of original construction).
■ Cracks and inadequate cover over steel reinforcement.
Sika Solutions■ Removal of loose concrete and
preparation of exposed reinforcement.■ Protect reinforcement with:
SikaTop®-Armatec 110 EpoCem®.■ Replace damaged concrete
with: Sika repair mortar.■ Provide a uniform, attractive
surface finish and protection with:SikaGard®-550W.
MECHANICALDAMAGE
StructureFactory Roof over Production Facilities
Problem■ Aggressive chemical attack on the
concrete.■ Followed by corrosion of the steel
reinforcement in a high temperature,high humidity environment.
Sika Solutions■ Removal of damaged concrete and
preparation of exposed reinforcement.■ Protect reinforcement with:
SikaTop®-Armatec 110 EpoCem®. ■ Replace damaged concrete:
SikaCem®-133 Gunite.■ Protect the surface from future
aggressive chemicals with: SikaGard® high performancecoating.
CHEMICALDAMAGE
13
StructurePrecast Reinforced Concrete Framed Office Building
Problem■ Alkali Aggregate Reaction (AAR/ASR)
in the concrete leading to typicalcracking and expansive gel formation.
Requirement■ Durable holding repairs to bridge
moving cracks and to significantlyreduce the rate of deteriorationthereby extending the service life ofthe structure.
Sika Solutions■ Mechanical preparation.
■ Patch repair and fill surface defects and cracks with SikaDur®-31epoxy mortar.
■ Provide crack bridging protectionagainst future water ingress withSikaGard®-550W.
CHEMICALDAMAGE
International Case Studies
StructureMulti Storey Concrete Parking Structure
Problem■ Freeze thaw damage on concrete
columns and soffits from condensationand deicing salts exposure.
Sika Solutions■ High pressure water jetting followed
by blast cleaning.■ Repair and reprofiling with:
SikaTop® mortars.■ Protection against future water
and deicing salt ingress withSikaGard®-680S (columns and soffits) and SikaGard®-550W(areas subject to cracking - parapets and external facades).
■ Joint sealing with Sikaflex® sealants.
■ Steel corrosion protection with Sika Icosit® coatings.
PHYSICALDAMAGE
14
International Case Studies
Structure150 metre (500 feet) Long Major Road Bridge
Problem■ Concrete damage on the parapet and
underside of the bridge due to freezethaw action accelerated by deicingsalts.
Sika Solutions■ Surface preparation and defective
concrete removal by highpressure water jetting.
■ Parapet: Sika MonoTop®-610 ascorrosion protection for exposedreinforcement and as a bonding bridgefollowed by Sika MonoTop® repairmortar at 3-6cm thickness.
■ Substructure: SikaTop®-Armatec 110 EpoCem® as corrosion protection, allowed to cure, and then repair by dry spray application of SikaCem®-133 Gunite repair mortar.
PHYSICALDAMAGE
StructureMulti Storey Residential Housing Block with Concrete Frame and Precast CladdingPanels
Problem■ Inadequate concrete cover to steel
reinforcement with extensive crackingand spalling after depth of carbonation reached the steel.
Sika Solutions■ Concrete surface preparation by high
pressure water jetting.■ Exposed steel reinforcement prepared
by blast cleaning.■ Steel reinforcement protection and
bonding bridge with SikaTop®-Armatec 110 EpoCem®.
■ Repair and reprofiling with Sikarepair mortar.
■ Crack bridging anti carbonation protection on large concrete surfaces with SikaGard®-550Wcoating.
■ Joint sealing with Sikaflex® sealants.
■ Galvanized balcony handrail protection with Sika Icosit® coatings.
CARBONATIONDAMAGE
15
Structure26 Storey Lightweight Insitu Concrete, Residential Housing Block
Problem■ Inadequate concrete cover over steel
reinforcement with subsequentcracking, staining and spalling.
Sika Solutions■ Preparation by blast cleaning.
■ Exposed steel reinforcement protectionwith SikaTop®-Armatec 110 EpoCem®.
■ Repair with SikaTop® lightweight mortar.
■ Levelling and pore filling with SikaTop® levelling mortars.
■ Crack bridging anti carbonation protection and architectural designfeature with SikaGard®-550W and Sikagard®-680S.
■ Joint sealing with Sikaflex® sealants.
CARBONATION DAMAGE
International Case Studies
StructureHistoric Reinforced Concrete Drinking Water Tower
Problem■ Externally carbonation depth had
reached the main steel reinforcementallowing expansive rusting to occurwith subsequent concrete crackingand spalling.
Sika Solutions■ Surface preparation by blast cleaning.
■ Steel reinforcement protection andbonding bridge with SikaTop®-Armatec 110 EpoCem.
■ Repair and levelling with SikaTop®
mortars.■ Anti carbonation protection and
enhanced appearance withSikaGard®-680S.
CARBONATIONDAMAGE
16
International Case Studies
StructureConcrete Parapet Wall at an Airport Parking Structure
Problem■ Galvanised steel handrail fixed into
the steel reinforced concrete edge beam with direct contact between galvanising and reinforcing steel leading to corrosion.
Sika Solutions■ Remove and reinstall Sikagard®
epoxy paint coated steel handrailswith SikaGrout®-42 (epoxy grout).
■ Patch repair and level damaged concrete with SikaTop® repairmortars.
■ Protect against future water ingress with Sikagard®-550W.
ELECTRICALDAMAGE
Structure1200metre (3/4 mile) Viaduct consistingof 10 bridges over road and rail tracks
Problem■ Extensive chloride accelerated
reinforcement corrosion particularly below expansion joints in the deck.
Sika Solutions■ Following replacement of bridge
deck joints.■ Removal of all damaged concrete.
■ High pressure water jetting (also to reduce residual chloride levels).
■ Blast cleaning to prepare exposed steel reinforcement.
■ Repair and reprofiling with SikaCem®-133 Gunite dry spraymortar.
CORROSIVECONTAMINANTS
17
StructureSecond Floor Pedestrian Walkway/Bridge at a Hospital
Problem■ Concrete damaged by freeze thaw
action and reinforcement corrosionaccelerated by chlorides from deicingsalts.
Sika Solutions■ Surface preparation by high pressure
water jetting and exposed steel reinforcement prepared by blast cleaning.
■ Steel reinforcement protection with SikaTop®-Armatec 110 EpoCem®.
■ Repair with SikaTop® mortars.
■ Protection against latent damages by impregnation with SikaFerroGard®-903corrosion inhibitor.
■ Crack bridging surface protection with SikaGard®-550W.
CORROSIVECONTAMINANTS
International Case Studies
StructureNew Light Rail Bridge Superstructure
Problem■ Inadequate low concrete cover with
future deicing salt exposure on the deck
■ Mechanical damage to architecturalpanels by a nearby bomb explosion.
Sika SolutionsBridge Deck Surface and Soffit■ Impregnation with Sika FerroGard®-903.
■ Protective coating to prevent futurewater and chloride ingress withSikaGard®-550W. ArchitecturalPrecast Parapet Panels.
■ Replacement with new thin sectionpanels using Sikament® superplasticiserand Sika FerroGard®-901 corrosioninhibiting admixture.
CORROSIVECONTAMINANTS
18
■ Sika Deck Coatings- for crack bridging balcony, podium and deck waterproofing plus elastic wearing surfaces.
■ Sikaflex® Joint Sealing- a unique range of one component sealants, specifically designed for compatibility with the Sika repair and protection systems.
■ Sika Icosit® Steel Coatings- for the protection of steel and galvanised steel surfaces such as handrails, window frames and support structures.
Additional Complementary Sika Systems
Summary Flow Chartof the Sika Process
Visual Survey
Staining,CrackingSpalling
Latentdamages
Repair &protect now?
Root causeanalysis
Detailedsurvey
Continueregular
monitoring
Cleanconcreteand markrepairs
Prepare steelPrepare
substrateRusted steel
present
Break out damagedconcrete
Fill with SikaRepair mortar
Apply Sikasteel primerand bonding
bridge
Protectagainst latent
damages?
N
Y
N
YN
Y
N
Y
N
Y
19
■ Sika Structural Waterproofing- well proven systems that provideinternal waterproofing for both new and refurbishment projects in basements, lift pits, cellars, car parks etc.
■ Sikadur® Resin Injection- structural resins for the injection and bonding of cracks and voids to restore integrity.
■ Sika Carbodur®
Structural Strengthening- externally bonded composite reinforcement system for structural strengthening and to increase load bearing capacity of floors, walls, beams etc.
Apply SikaFerrogard 903
ApplySikagard
impregnation
Protect & enhance
appearance
ApplySikagard
680S/670Wcoatings
Crack-bridgingability
needed?
Apply Sikalevellingmortar
ApplySikagard550W to
facades andapply
Sikafloor todecks
Apply SikaIcosit Steel
coatings
Apply Sikaflexjoint sealents
Finalinspection
Set upCorrosionMonitoring
System
MaintenanceManagement
Strategy
HAND OVER
Y Y
N N
Y
Y
N
Technology and Concepts for the Repairand Protection of Reinforced ConcreteAlso Available from Sika
Cer
tified Quality System
ISO
9001/ EN 29001
Cer
tifie
d Management System
ISO 14001
Environmental
Protection
Quality
Production WP.
07.0
4.3k
The information, and, in particular, the recommendations relating to the appli-cation and end-use of Sika products, are given in good faith basedon Sika’s current knowledge and experience of the products when properly stored, handled and applied under normal conditions. In practice, thedifferences in materials, substrates and actual site conditions are such that no warranty in respect of merchantability or of fitness for a particularpurpose, nor any liability arising out of any legal relationship whatsoever, can be inferred either from this information, or from any written recom-mendations, or from any other advice offered. The proprietary rights of third parties must be observed. All orders are accepted subject to our cur-rent terms of sale and delivery. Users should always refer to the most recent issue of the Product Data Sheet for the product concerned, copies ofwhich will be supplied on request.
Sika LimitedWatchmeadWelwyn Garden CityHertsAL7 1BQ
Tel: 01707 394444Fax: .01707 329129email: [email protected]
Sika Ireland LimitedUnit 3 Ballymun Industrial EstateDublin 11Ireland
Tel: (01) 8620709Fax: (01) 8620707email: [email protected]
Sika Technology Series Sika Product Series
Sika Concrete Series Sika Ferrogard® Technology