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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


years

Dev

elo

pm

ent

of

corr

osi

on

y = rateof corrosion

ny = rateof corrosion

New start after repair

Extension of service life


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


years

Dev

elo

pm

ent

of

corr

osi

on

y = rateof corrosion

y/2 = rateof 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


■ 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


■ Water permeability andabsorption

Sealing withHydrophobicImpregnations■ Penetration ability



■ Freeze thaw resistance

Anti-CarbonationCoatings■ Bond strength

■ Cross hatchperformance



■ 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


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


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.


■ 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.


CARBONATION DAMAGE


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


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.



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.


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

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■ 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

technology and concepts - repair and protection of ... and protection of reinforced concrete. 2 ......

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