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Technology and Concepts for Structural Strengthening

Solutions with Sika® Systems

Iron and Steel

Timber

Masonry

Concrete

StoneStone

Iron and Steel

Sika® CarboDur® Systems

Timber

Structural Strengthening with Sika®

Strengthening System Requirements

▲ Static Loading

▲ Vibration/Dynamic Loading

▲ Stiffening

▲ Fatigue Resistance

▲ Durability

Externally bonded reinforcement increases theload carrying capacity of structural members andwill also reduce deflection. The tensile stressinduced by imposed loads must be shared by themember and the external reinforcement. Steelplates have been used for this purpose for somedecades and research started on compositematerials in the early 1980’s.

The stress is transferred from the structuralmember to the bonded reinforcement by astructural adhesive. The requirements for thismethod of strengthening have been proven byextensive testing. This included large scale beamtests under dynamic loading conditions andextensive freeze-thaw cycling. Sika® CarboDur®

Systems are fully proven under the most extremeconditions.

Walls BeamsAccesOpeninColumns

Structural RequirementsInclude:

▲2 Concrete Failure in Compression

CarboDur® Composites

The performance of the Sika® CarboDur® has beendemonstrated even in compression zones. A thickerplate, such as steel, would undergo suddendelamination but Sika® CarboDur® plates remain fullybonded until concrete failure in compression.

Durability is a prerequisite for astrengthening system. The Sika®

CarboDur® Systems, plates, fabrics, and adhesives, all haveexcellent resistance to corrosive andaggressive chemical influences.

Specifically: There is no risk ofunderrusting.

Requirements From Environmental ExposureInclude:

▲ Temperature Extremes and Variation

▲ Moisture/Humidity

▲ Freeze/Thaw Action

▲ Corrosive/Chemical Influences

▲ Ultraviolet Light

▲ Fire Resistance

Decks/Floorssngs

MasonryWalls

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Beams

Concrete Failure

The Simple Steps for Site ApplicationSika® CarboDur® Plate Process

The Simple Steps for Site ApplicationSikaWrap® Process

Sika® Carbodur® Composite Systems –

▲ Light and Easy to Carry

Available in rolls of any length

▲ Exact Lengths

Cut on Site to required Length

▲ Controlled Application

Apply Sikadur®30 Adhesive

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Advantages of Sika®

▲ Minimal thickness

▲ Corrosion resistant▲ Precise performance properties (defined)

▲ Range of dimensions – optimum design

▲ Choice of modulus

▲ Factory prepared for use

▲ Low temperature application with heated plates

▲ Elevated temperature in service grade

▲ Can be post tensioned

▲ Very high strength

Advantages of Sika® CarboDur®

Pultruded Plates

▲ Controlled Resin Distribution

Impregnation of Fabricusing Saturator Machine

Applying SikaWrap® Hex®

Fabric to the Column

▲ Flexible to Accommodate the Shapeof the Structure

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Advantages

▲ Reduced Labour Requirement

Easily Placed in Position

▲ No Temporary Supports Required

Pressed into Position by Roller

▲ Easy Detailing with No Laps

Completed Deck Strengthening Project▲4 ▲5 ▲6

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CarboDur® Composites

▲ High strength to weight ratio

▲ Lightweight – easy to apply

Advantages of SikaWrap®

Fabrics

▲ Shear resistance

▲ Impact and blast resistance

▲ Very flexible for details

▲ Easy on circular and square members

▲ High strength

▲ Carbon fibre and glass fabrics available

Note: Unidirectional fabric may be applied in any direction

▲ Easy Site Application especiallyaround Details

▲ Minimal Downtime and ReducedAesthetic Impact

Smoothening SikaWrap® Hex®

Fabric Completed Column▲3 ▲4

Project:A413 Farm Underpass, Great Missenden, Bucks.

Problem:The bridge had to be upgraded totake the Department of Transportnew 40 tonne requirement.

Solution:▲ Local structural repairs

compatible with the parentconcrete were undertaken withSikatop 122® and crackinjection with Sikadur® 52.

▲ The bridge was strengthenedby bonding Sika® CarboDur®

plates to the soffit of the deckslab with Sikadur® 30.

▲ Sika® CarboDur® laminates Type S1012 were selected, total length 180m.

Worldwide Case StudiesBridges and Civil Engineering

United Kingdom

Strengthening with local repairs to a highway cattle underpass

© DiskArt™ 1988

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Project:Dudley Port Bridge, Sandwell.

Problem:The bridge had to be upgraded from its existing 17 tonne capacity to take theDepartment of Transport’s new 40 tonne requirement.

Solution:▲ The bridge was strengthened by bonding Sika® CarboDur® plates

to the soffit of the deck slab.

▲ The plates were bonded withSikadur® 30 transversely andlongitudinally to achieve therequired load distribution.

▲ The total length of Sika®

CarboDur® laminates Type S1012 employed was 600m.

▲ Finally, a cementitious render ofSika® MonoTop® 612 was sprayapplied, using the ‘wet’ process,to the soffitt and trowelled to asmooth finish.

United Kingdom

Bridge deck over waterway with very limitedheadroom

© DiskArt™ 1988

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United Kingdom

Strengthening ofbridge columnsfor heavy vehicleimpact

© DiskArt™ 1988

Project:Bible-Christian Bridge, A30 Bodmin-by-Pass, Cornwall.

Problem:Strengthening of the columns was needed to comply with the Departmentof Transport’s Highways Agency impact loading requirements.

Project:Horgen Transporter Bridge, Zurich.

Problem:Insufficient reinforcement in the cantilevered deck.

Solution:▲ Apply CarboDur® S1212 plates to the top surface

above the root of the cantilever.

▲ Protect with SikaTop® Armatec-110 EpoCem® andSikafloor® 82 EpoCem®.

▲ Re-apply waterproof membrane and surfacing.

Switzerland

Strengthening to top surface of cantileveredbridge deck

Sika® CarboDur® S1212 plates applied at 600 mm centres

Bitumen membrane torching

Solution:▲ Concrete prepared and primed

with Sikadur® Hex® 300 lowviscosity impregnating andsealing epoxy resin.

▲ Sikadur® Hex® 306 thixotropicepoxy resin adhesive wasapplied to the glass fibre fabricSikaWrap® Hex® 100 G sheets.

▲ The designed lengths of fabricwere unrolled onto the columnand smoothed into position.

Worldwide Case StudiesBridges and Civil Engineering

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Project:Kings College Hospital, London.

Problem:Strengthening was required toupgrade the roof to a floor foradministrative offices. The narrowwidth at the soffit of the beamsprevented the use of conventionalsteel plates because of theminimum width to thickness rationecessary for their design.

Solution:▲ Strengthening with Sika®

CarboDur® laminates bondedwith Sikadur® 30.

▲ Sika® CarboDur® Type S512plates were used on the 80mmwide beams. The total length ofSika® CarboDur® laminatesemployed was 1.3km.

United Kingdom Strengthening

of existing roofbeams to takenew floor loading

© DiskArt™ 1988

United Kingdom

Large volume repair, protectionand strengthening of bridge deck

© DiskArt™ 1988

Project:St Columb Major Road Bridge, Cornwall.

Problem:Chloride ingress had led to the need for repair and then strengthening was required to take 40 tonne vehicles.

Solution:▲ Damaged concrete was removed and Sika®

FerroGard® 903 corrosion inhibitor was appliedto protect against latent damages due to residualchlorides. Extensive soffit repairs wereundertaken using Sika® MonoTop® 612 repairmicro-concrete applied using the wet sprayprocess.

▲ When hardened the Sika® CarboDur® type S1012 plates were bonded withSikadur® 30 and strain gauges, were fixed to monitor the stress transfer.

▲ As a final protection against both further chloride ingress and carbonation,an elastic, crack-bridging coating of water-based Sikagard® 550W wasapplied over the exposed concrete surfaces.

Commercial & Institutional Buildings

Worldwide Case StudiesResidential Buildings

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Project:A multi-storey block of flats inLoano-Genova.

Problem:Insufficient reinforcement resultedin 12mm deflection of thecantilevered balconies.

Solution:▲ The outside edge of the

cantilevered balcony wasjacked and propped.

▲ Sika® CarboDur® Type S512plates were adhered withSikadur® 30 to the top surfaceof the concrete over the root ofeach cantilevered balcony.

▲ Under a test load of 450kg theresulting deflection was only2mm.

Italy Strengthening of cantileveredbalconies

Project:A multi-storey block of flats inChemnitz.

Problem:Insufficient reinforcement in thebalconies resulted in unacceptabledeflections. Water ponded on thetop of the deck Strengthening ofthe slabs was required.

Solution:▲ Sika® CarboDur® plates were

applied longitudinally to theconcrete soffits with Sikadur®

30 adhesive.

▲ A levelling mortar was appliedto the top of the balcony deckwith Sika Monotop® mortar.

▲ The total length of Sika®

CarboDur® laminates Type S512 used was 13.5km.

Germany Longitudinalstrengthening of balconies

© DiskArt™ 1988

Project:Allders Department Stores,Croydon & Portsmouth.

Problem:The installation of two newescalators at Croydon and a new stairwell at Portsmouthnecessitated holes to be cutthrough the existing floor slabs.

Solution:▲ Sika® CarboDur® plates were

bonded with Sikadur® 30 alongthe edges of the holes to be cut.

▲ Sika® CarboDur® Type S1012 plates were selected.

▲ The total length of Sika®

CarboDur® laminates employedwas 250m.

Worldwide Case StudiesCommercial and Institutional Buildings

United Kingdom

Strengthening offloor slabs foraccess openings

© DiskArt™ 1988

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Project:Yarborough School, Lincoln.

Problem:The pre-cast concrete staircasehad the treads installed upsidedown. Minimum disruption to theschools activities was essential.

Solution:▲ The Sika® CarboDur®

Type S512 plates were bondedwith Sikadur® 30 centrally to the underside of the treads.

▲ The total length of Sika®

CarboDur® laminates employed was 80m.

▲ Sikadur®-52 was injected intothe cracks after bonding wascomplete.

United Kingdom Strengthening

of stair treads© DiskArt™ 1988

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Project:Office Building, Mühlebachstr, Zurich.

Problem:Conversion of apartments to offices required structural alterations including removal of a load bearing wall. Redistribution ofload plus increased seismic and wind load design was required.

Solution:▲ To strengthen and stiffen two

existing brick walls with Sika®

CarboDur® laminates.

▲ Sika® CarboDur® Type S1012 plates were applied to the brickwork with Sikadur® 30.

Strengthening of masonry wallsfor seismic andwind loading

Switzerland

Project:Monastery at Eschenbach

Problem:Excessive deflection of historicoak beams causing concerns for the structural safety.

Solution:▲ Jack the beams as far as

possible.

▲ Prop the beams in position.

▲ Strengthen with the Sika®

CarboDur® System.

▲ Two strips of Sika® CarboDur®

laminate Type H514 withSikadur® 30 adhesive were usedon each of the wooden beams.

Switzerland

Strengthening of timberbeams to preventexcessive deflection

Special Circumstances

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Performance of Sika® CarboDur® Systems in FireWhen strengthening with steel orcarbon fibre, fire can be a concern.However, in the majority ofsitutations, it is not necessary toprotect the strengthening systemagainst fire. The unstrengthenedresidual load carrying capacity of thestructural element, under fire limitstate conditions, will be more than theapplied loading. The design will stillhave an adequate factor of safetyagainst collapse.

Due to their lower thermalconductivity Sika® CarboDur® platesgive improved performance over steelin the event of fire. This is due to theirsuperior insulating characteristicswhich reduce the rate of heat transfer.

In 1994, reinforced concrete beamswere subjected to fire tests in theEMPA furnace. The beams wereloaded in four point bending bymeans of hydraulic jacks. The furnacewas heated in accordance withISO 834 to a temperature of 925°C.

One control beam was unplated,another had additional externallybonded steel plate reinforcement anda further four beams werestrengthened with Sika® CarboDur®

laminates.

After 8 minutes the steel platedebonded and fell to the floor, theSika® CarboDur® plates sufferedsurface damage to the fibres andfinally debonded after one hour.

Fire resistant boarding can beprovided to further protect the plates,if and where required.

0

200

400

600

800

1000

0 10 20 30 40 50 60 70 80 90

ISO-Standard fire test

Time [min]

Tem

per

atur

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The EMPA Furnace Temperature Development Curve

The Furnace for Fire Testing at EMPA, Switzerland

Fire Resistant Boards can be used to Provide Additional Protection If and Where Required

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Fatigue tests were conducted onreinforced concrete beams with bothstressed and unstressed externallybonded Sika® CarboDur® laminates.Ultimate strengths were previouslyestablished in static load tests. Thebeams were subjected to cyclicloading of maximum 35% andminimum 16% of the ultimatecapacity.

In both cases the initial failure wasevidenced by the fracture of theinternal reinforcing bars by fretting.This led to disintegration of theconcrete around the fracture, theremainder of the beam held togetherby the Sika® CarboDur® laminate.

Design of Shear Strengthening

Fatigue performance on T-beams

With Sika® CarboDur®

Plates

Profiled plates can be produced to allowan external shear link to be formedaround the external surfaces of a beam.

Loaded T-Beam at the EMPA

Fatigue Test Showing Disintegrated Concrete around Tensile Reinforcementwhich has Fractured due to Steel Fretting

With SikaWrap® Fabrics

SikaWrap® fabrics can be placed andsmoothed on to flat or curved concretesurfaces. In this case they werepositioned either side of the beam in the shear zone to provide the desiredincrease in strengthening.

Application of SikaWrap® in the Shear Zone

Sikadur® –Epoxy resin based structural adhesivesproven in segmental bridge construction and structuralstrengthening since 1960

Sika® CarboDur® – The Strengthening System with Proven and on Extensive Contract References

Sikadur® adhesives have outstanding mechanical and chemical properties whichhave been repeatedly proven in extensive testing worldwide.

Specific Test Data which gives the precisely defined adhesive performance includes:

▲ Water absorption▲ Modulus of elasticity▲ Shear strength▲ Creep resistance▲ Corrosion resistance▲ Glass transition temperature

▲ Compressive strength▲ Tensile strength▲ Bond strength▲ Durability▲ Squeezability and sag resistance▲ “Wetting” ability

Sika® CarboDur®–The long-term tested strengthening system

1984– First trials at EMPA in Switzerland

1991– First commercial use in Switzerlandon a reinforced concrete and wooden bridge

Defined adhesive performance

The System with definedperformance properties

External Steel Plate StructuralStrengthening with Sikadur®

Adhesive

Segmental Bridge Constructionwith Sikadur® Adhesive

Water Absorption of Sikadur ® Adhesives

Sins Concrete and Wooden Bridge, SwitzerlandDynamic Load Testing▲14

Conventional Epoxy Adhesives

SIKADUR® 31 PBA

Time

6.0

% WeightGain

1.0

Performance in Long Term Testing

Sika ® CarboDur ® –Pultruded Carbon Fibre plates proven in testing since 1984The Sika® CarboDur® plates have undergone continuoustesting and development from 1984 including monitoringof the first commercial applications in Switzerlandbeginning in 1991.

The high quality and quantity of T700 carbon fibres usedin the epoxy bound matrix provides 70% of the pultrudedplate cross section giving precise performanceproperties.

Measurement oftensile strength andmodulus of elasticity

1998 – Launch of the Sika® Hexcel® Strategic GlobalAlliance and Introduction of the Complete Sika® CarboDur®

Plate and Fabric Wrap Range of Systems

Defined plate performance

1994 – Start of Large Scale Production of Plates byPultrusion Process

70% Fibre Content giving Precise Performance Properties

Prepared Test Sample

Continuous measurement of the modulus of elasticityand other properties are made during production toensure consistent quality (ISO 9000 standards).

Sample at Failure

The Pultrusion Process for Manufacture of Sika®

CarboDur® Plates

Sika® Hexcel® Saturator for Impregnation On-Site

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ModulusMPa

No. ofsamples

Technology and Conceptsfor Structural Strengthening

Sika® Technology Series

Sika® Quality and Durability

Sika® Product Series

Sika® Information Series

Also Available from Sika®

Sika LimitedWatchmead, Welwyn Garden City,

Herts, AL7 1BQ Fax: 01707 329129

Telephone: 01707 394444e-mail: sika@dial.pipex.com

Sika Ireland LimitedUnit 3 Ballymun Industrial Estate,

Dublin 11, IrelandFax: (01) 8620707

Telephone: (01) 8620709e-mail: info@sika.ie

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9001/ EN 29001

Cer

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C O N S T R U C T I O Nwww.sika.com

The information, and, in particular, the recommendations relating to the application and end-use of Sika products, are given in good faith based on Sika’s current knowledge andexperience of the products when properly stored, handled and applied under normal conditions. In practice, the differences in materials, substrates and actual site conditions are suchthat no warranty in respect of merchantability or of fitness for a particular purpose, nor any liability arising out of any legal relationship whatsoever, can be inferred either from thisinformation, or from any written recommendations, or from any other advice offered. The proprietary rights of third parties must be observed. All orders are accepted subject to ourcurrent terms of sale and delivery. Users should always refer to the most recent issue of the Technical Data Sheet for the product concerned, copies of which will be supplied on request.

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