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CRLCONCRETE REPAIRS Ltd

Speaker: Bob Berry

Senior Business Development Manager


CRL-Concrete Repairs Ltd• Multi-discipline refurbishment Contractor• Founded 1954 • Turnover 2008-2009: £27m• Nationwide professional contract service• Largest contract to date £5m• Industry award winning status• Five UK Regional Offices• Abu Dhabi Middle East Regional Office


Presentation

Structural Strengthening of Reinforced Concrete with

Composite materials


Content• Background• Materials used• Research• Properties• Design Considerations• Application techniques• Project profiles


Externally Bonded Reinforcement

Definition. • An Externally Bonded Reinforcement system

increases the load carrying capacity of structural members and hence reduces deflection.

• The tensile stresses induced by imposed loads must be shared by the member and the external reinforcement system.

• These stresses are uniformly transferred from the structural member to the bonded reinforcement by means of a structural adhesive


Why Composites for Construction?

• Advantages….• lightweight • good specific mechanical properties• good durability• readily formed to complex shapes• ability to tailor mechanical properties• guaranteed mechanical properties• can be manufactured to any length• in-built surface preparation• can be pre-stressed….


History• Composites are not

something new in• construction. They have

been used for several decades

• used some benefits but not all, e.g. GRP


Reasons for Strengthening

• Requirements for increased load capacity (e.g. Change of use of regulations)

• Insufficient or incorrectly located reinforcement

• Damage (e.g. Corrosion or impact)• Change of structural form (e.g. Cutting

holes through slabs or removal of supports)


Strengthening with Composites offers significant benefits to the contractor,

designer and the client/owner.• Increased range of design options• Choice of composite and physical properties• Non corrosive material• Maintenance free solutions• Minimum disruption to the operation of the structure• Ease of handling• Ease of application• No need for expensive access equipment• Ability to strengthen a wide range of structural members• Ability to mould in-situ• Quality controlled manufacture of all components


Requirements of a strengthening system

• Structural requirements• Dynamic loading• Stiffening• Static Loading• Creep Resistance• Durability


Requirements of a strengthening system

• Environmental/Exposure requirements• Temperature (extremes & variation)• Moisture• Freeze/thaw• Corrosion• Ultra violet radiation• Fire resistance


- Flatness of substrate- Quality of substrate- Possibility of ongoing corrosion- State of stress in the element- Future loading requirements

SYSTEM DESIGNCONSIDERATIONS


Externally Bonded Systems provide solutions for the strengthening of all

types of structure:• Buildings• Bridges• Tunnels• Tanks/Vessels• Multi Storey Car Parks• Marine• Industrial• Water• Power/Nuclear• Blast Containment


Composite materials Composite materials consist of:consist of:

Fibres Fibres

MatrixMatrix


Composite elements manufactured through a warm extrusion process in which they are impregnated with epoxy resin while subjected to a tensile stress (Pultrusion)

Less flexible than fabrics they are applicable only on specific types of repair work

Pultrusion process


Development of carbon technology

Manufactured as a uni-directional continuous-fibresheet, supplied in rolls

• Used for structural reinforcement in Japan for >14 years


Pultruding Carbon Fibre


Carbon• Wide range of grades with

different mechanical properties• high strength and stiffness• brittle and fail at low strain levels• negative coefficient of thermal

expansion• electrically conductive• may cause galvanic corrosion


E-glass

• Low strength and stiffness• low cost• more dense - heavier structures• electrically non-conductive• good corrosion resistance• can be attacked by strong

alkaline solutions


Bi-directional AR-GLASS fibres

Reinforcement of masonry


Polymer

Silo

Mixers

Blender Filters

Wash / Neutralise

Spinning

Dryer

Bobbin

Sulphuric Acid

CausticThe Manufacturing Process for Kevlar® Brand Yarn


Kevlar fabric


Aramid Kevlar• High tensile strength• high elongation to failure• low density - lightweight

structures• low compressive strength• negative coefficient of thermal

expansion• impact resistance increased• non conductive


6mm BONDED STEEL PLATE• 6mm bolted plate• 110 kg. dead load• Mechanically lifted

REINFORCED CONCRETE• 1110 kg dead load• Formed and cured

FRP PLATE/SHEET• Thin layer - resin bonded• 1.5 kg dead load• Placed by hand

Comparison of techniques


Steel plate bonding


- Additional dead load- Limited plate lengths- Possible future corrosion- Drilling & bolting issues- Longer installation time- Health and safety implications

STEEL PLATE CONSIDERATIONS ...


Applications

• Architectural• Bridges• Strengthening• Structural• New construction• Applications for developments• Various substrates…only concrete?


Bridges


Strengthening / repair


Application techniques


Contaminants removal


Cutting CFRP & Applying Resin Adhesive


Farm underpass, Great Missenden…vehicle loading to 40 tonnes


New Moss Lane Cast Iron Bridge


Cast Iron Substrates


Application of plate to cast iron beam


Harbour City MSCP 4 extra floors, 164 columns strengthened, 10 spaces

taken at one time.


Application over water


Haven Bridge, Lincolnshire… vehicle loading to 40 tonnes


Tay Bridge- Dundee• Condition of the

columns prior to protection using Kevlar.

• *Note the shape of the columns

• Trials carried out first


Tay Bridge- Dundee• View of completed

column prior to the coating system being applied


Allders Stores, Croydon & Portsmouth... to facilitate escalator/lift installations


Kings College Hospital… to carry new floor load


Beau Sejour Leisure Centre, Guernsey… structural modifications/change of use


Background to West Burton

Fiddler’s Ferry disaster


West Burton Power Station• Built in 1960’s• Previous

strengthening with a sprayed mantle using Gunite

• When wind reached 25 knots structure had to be evacuated

• Foundations already pre- stressed


West Burton Power Station

Shuttering being prepared for concrete ring beam



Layers of Kevlar applied and smoothed by hand and roller



Peel ply added to the final coat of wet resin for future coating


QAFCO-Qatar


QAFCO- Qatar UAE

1.8mm thick carbon on roll Spacers to determineresin thickness


QAFCO- Qatar UAE

Resin applied to tower Resin applied to laminate


QAFCO- Qatar UAE

Carbon held in place whilstcuring Keeping in the shade


QAFCO- Qatar


FRP Systems- the futureRods and cables- grids and mats- very

high modulus plates for cast iron structures

RebarRebar

FRP SystemsFRP Systems

GridGridFRP SystemsFRP Systems


Test Walls Strengthened with AK-60 Laminates

Arena blast test with 4 different types of wall placedequidistant from the charge.


Solid English Bond Brick Wall Strengthened with AK-60 Kevlar®

Laminates

Outer Face- Blast Side Inner Face


Brick and Light Weight Block Cavity Wall Strengthened with AK-60 Kevlar®

Blast side Inside face of wall


English Bond Brick Wall with Rubber Coated Kevlar® Fabric

Blast side of wall Inner face no damage


Canary Wharf Blast MitigationProtection against terrorism2500m2 of KevlarProved it self after PentagonHigh potential in UK market


Externally bonded systems provide solutions for all types of strengthening:

• Flexural• Shear• Impact• Blast• Seismic• Stiffening• Deflection• Fatigue• Restraint


Types of substrates

• Concrete• stone• cast iron• brickwork• steel• timber


Perceived barriers• specification of materials • costs of materials • design guidance • lack of awareness• fire performance• long-term durability• past experience • environmental ?


FRP SheetsAdvantages

• lightweight- minimal additional dead load, minimal thickness and flexible

• corrosion resistant- high durability, low maintenance

• ease of installation- cost savings, minimal down-time


Quality Control

• The UD Fabrics (Certificate of Conformity)

• Tensile properties of fabrics

• Tensile properties of laminates


Testing properties of KEVLAR® UD fabrics


Quality Control SystemsBond tests

Tap testTap test Pull testPull test


Testing of Pultruded carbon onto steel


Pultruded Kevlar testing on steelFribourg University (CH)


Pultruded Kevlar testing on steel


Testing of pultruded carbon onto steel University of Bristol


Design codes

• MBrace Design Guidelines• BD 84/02• Euro-codes


Product Selector

*******Blast

*******Seismic

******Impact

******Shear

********Flexure

Wall Strengthening

*****Seismic

*****Impact

*******Shear

*******Flexure

Column Strengthening

******Shear

*******Flexure

Slab Strengthening

*******Shear

*******Flexure

Beam Strengthening

Aramid Fibre WrapGlass Fibre WrapCarbon Fibre WrapCarbon Fibre

Plate

Key* Acceptable** Good*** Excellent


Useful Documents


“Fibre composite strengthening is proving to be a cost-effective technique, which can bring great benefits to the owners of structures, chiefly because of the speed of installation, leading to less disruption … “

THE CONCRETE SOCIETY


“ Whilst the approach is simple, composite strengthening is highly dependent on quality of workmanship. It is vital that an experienced repair contractor, using suitably trained and supervised staff, carries out the work. This is one of the key points identified in the Concrete Society Technical Report, TR57 ... “

THE CONCRETE SOCIETY


- To promote & develop the practice of concrete repair

- To advance technical training & education

- To represent members in common interests

- To improve liaison with professional bodies, authorities & specifiers

CRA WAS ESTABLISHED ...


- Accredited to ISO 9000 - Conform to the CRA Codes

of practice- Operate in accordance with

contract, relevant British Standards & working practices

- Abide by all current Health &Safety requirements

- Observe the highest standards of business integrity

- Positive commitment to staff training

CRA MEMBERS ARE ...


• design guidelines• full support• fully trained contractors

FRP Systems…..more than just materials!


Conclusions

• Polymer composites have found applications in the construction industry

• Polymer composites offer the architect, designer and engineer many advantages over traditional construction materials

• New fibre and resin combinations enable wider product and application range

• Polymer composites have a large part to play in the construction industry and their contribution can only increase in the future


WHY CRL WHY CRL …………..- Accredited to ISO 9001, 14001,

18001 through an integrated Health & Safety, Environment & QualityManagement System (SHEQ)

-Conforms to the CRA Codes of practice

-Operates in accordance with contract,relevant British Standards &working practices

- Abides by all current Health &Safety requirements

- Observes the highest standards of business integrity

- Positive commitment to staff training- Award winning industry status


CRL CRL …………..- Accredited to ISO 9001, 14001,

18001 through an integrated Health & Safety, Environment & QualityManagement System (SHEQ)

- Industry accreditation - Conforms to the CRA Codes of

practice- Operates in accordance with - contract, relevant British Standards &

working practices - Abides by all current Health &

Safety requirements- Observes the highest standards

of business integrity- Positive commitment to staff training


CRL is committed toCRL is committed to……....- Provide a safe & healthy working environment for all

- Total Client satisfaction- Promote & develop the practice of concrete repair & protection

- Advance in house technical training & education

- Liaise with professional bodies, authorities, specifiers & institutions

- Maintain its position as the market leader in this contract discipline

- Innovation & new technology- Continued success by continuous improvement


Integrated Health & Safety, Environmental & Quality Management system (SHEQ) AccreditedProfessional & Industry Association Membership includes

– The Concrete Society – Concrete Repair Association (CRA)– Corrosion Prevention Association (CPA) – Sprayed Concrete Association (SCA)– British Parking Association (BPA)– Civil Engineering Contractors Association (CECA) – Insulated Render & Cladding Association (INCA)

BBA Approved Contractor. major material suppliersConstructionline, Exor, Archiles, Link Up accreditationHighway Agency, Welsh Assembly Government (WAG), Scottish Executive approved English Heritage registeredInvestors in People accreditedProject Performance Assessment SurveyCHAS Accreditation.

Quality

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•

•••••


The secret of success ?


THANK YOU FOR YOUR ATTENTION

Email: [email protected]: www.concrete-repairs.co.uk

www.crlfacades.co.ukwww.crlsurveys.co.uk

Helpline: 0117 986 8088

South West, South Wales & South Midlands Regional Office