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    One of the Greatest Buildings of the 20th Century in Sydney is Built on a special meeting place known to the Gadigal people of the Eora Nation for thousands of years as Tubowgule.

    December 12th, 2019 Posted by Uncategorized 0 thoughts on “One of the Greatest Buildings of the 20th Century in Sydney is Built on a special meeting place known to the Gadigal people of the Eora Nation for thousands of years as Tubowgule.”

    The building is the Sydney Opera House which is World Heritage listed as “a masterpiece of human creative genius” and its sail like shape is recognisable world-wide as being synonymous with Sydney and Australia.

    The unmistakable shape of the Sydney Opera House sails fit in with the building’s natural surroundings on Sydney Harbour. The design of the sails was a challenge until Architect Jorn Utzon delivered the “spherical solution” in the design of the sails where the ten roof sails were built from segments of the same sphere.

    CONSERVATION OF THE STRUCTURE

    A 2018 Report looked at three high priority areas for the development of the Conservation Management Plan thanks to a grant from the Getty Foundation:

    ROOF SAILS

    The most recognisable part of the Opera House building, the sails are fully exposed to the marine environment, and could be vulnerable to water ingress should there be any failure in the ceramic tile skin, or in the grouting inside the post-tensioning ducts of the ribs. Regular inspections of accessible areas indicate that the condition of the protective system is good, however the Opera House is searching for new non-destructive testing methodologies that will enable the condition of the inaccessible interior of the sail structures to be monitored.

    ROOF PEDESTALS

    These steel-reinforced concrete structures at the base of the roof sails are completely exposed to the natural elements and to human touch. There is a particular impact from rainwater runoff, which causes erosion and biological growth on the structures. Protective coatings have been trialled in the past, and all have been rejected due to either being ineffective, or having an unacceptable architectural impact.

    UNDER THE BROADWALKS

    The Broadwalks are built on steel-reinforced concrete piles, which stand in the Harbour. The Western Broadwalk is fitted with cathodic protection, while the Northern and Eastern Broadwalks are not. The project studied the condition of the concrete under the Northern Broadwalk.

    Ref; Sydney Opera House, Concrete Conservation Project, Final Report Summary, August 2018

    http://www.getty.edu/foundation/pdfs/kial_report.pdfm/sydney_fin

    THE DESIGN LIFE

    The design life of the Sydney Opera House structure is 250 to 300 years.

    Under the Conservation Management Plan after more than 50 years exposed to a marine environment and the impacts of millions of visitors, some specific areas of risk in the concrete re being monitored through a robust preventative and corrective maintenance program. It is timely to undertake closer analysis of the condition of the steel-reinforced concrete in the structure to ensure its longevity.

    2000 SYDNEY OLYMPICS

    As Sydney prepared to host the 2000 Olympics, the Opera House kicked off an Olympic Arts Festival with ‘Tubowgule’. To the sound of didgeridoos and clapping sticks, dancers evoked the celebrations and ceremonies that had occurred on Bennelong Point for thousands of years.

    OUR FIRST NATIONS PEOPLE

    The Sydney Opera House celebrates the richness of our First Nations people and their culture through its First Nations Program.

    THE FIRST PERFORMANCE

    The first performance at the Sydney Opera House was in 1960 when Paul Robeson climbed the scaffolding and sang Ol’ Man River to the construction workers as they ate lunch.

    Video: Paul Robeson https://www.youtube.com/watch?v=Eg7bPgrosAE

    VIVID SYDNEY

    The Sydney Opera House is featured in colour and music at the annual Vivid light spectacular in Sydney.

    Video: Vivid Sydney 2019 https://www.youtube.com/watch?v=NnzO5U6zEvo

    GREAT PERFORMANCES

    The Sydney Opera House is the cultural heart of Sydney with great ballet and opera performances by our own “La Stupenda” Dame Joan Sutherland and New Zealand’s Dame Kiri Te Kanawa, Rudolf Nureyev and Dame Margot Fonteyn, Sir Robert Helpmann and the Australian Ballet………..and so on.

    Video: The Best Performances of Dame Joan Sutherland from the Sydney Opera House https://www.youtube.com/watch?v=XoZtnsJp0Zg

    What is Carbon Fibre Structural Strengthening?

    October 22nd, 2019 Posted by Uncategorized 0 thoughts on “What is Carbon Fibre Structural Strengthening?”

    Carbon fibre reinforced polymer is an extremely strong and very durable material which is applied externally to strengthen concrete structures without the need to demolish and replace the existing structure such as concrete beams, suspended slabs and structural columns.

    This is a very cost effective method for structural strengthening where a structure is required to carry increased loads or where the structures design is inadequate.

    Carbon fibre is woven into in a matrix of Polymer Resin to form the material and its properties are dependent on the ratio of fibre to polymer as well as the structure of the matrix. This material is very light weight as it has a high strength to weight ratio.

    FCS Concrete Repairs are experienced in the application of CFRP plates, strips and wrap to the structural strengthening of building structures.

    FCS Concrete Repairs install the CFRP in accordance with the design prepared by Qualified Structural Engineers.

    A recent applications of this technology:

    Project: Surry Hills

    Structural Strengthening of Soffit.

    The scope of work was to supply all labour, materials, tools, equipment and materials for the Works associated with the Strengthening Sika CarboDur M Carbon Fibre Strips.

    Methodology:

    • All work and requirements as per Sika CarboDur® Method Statement and PDS.
    • Preparation Grinding / Blasting surface.
    • Pull-off Tensile strength testing of the concrete substrate.
    • Tolerance, surface deviation, level measurement and testing to ensure minimum tolerances required.
    • The substrate moisture content must be tested and verified.
    • Plate pull-off testing semi-destructive Quality Control.
    • High Build epoxy to top of slab. Levelling 0 -10mm.
    • Remove all Services and Ceiling Tiles and Ceiling Grids, providing unimpeded access.
    • Protect Completed Product to ensure the Sika CarboDur® is not cut or drilled through or tampered with.
    • Generally repair all test holes and make good.
    • Clean and remove overspill, patch and make good, as required.
    • Conduct Testing and Commissioning.

    Product recommended by FCS Concrete Repairs for structural strengthening in this application:

    Sika® CarboDur® M

    Sika® CarboDur® plates are pultruded carbon fibre reinforced polymer (CFRP) laminates, designed for strengthening concrete, timber, masonry, steel and fibre reinforced polymer structures.

    Sika® CarboDur® plates are bonded onto the structure as externally bonded reinforcement using Sikadur®-30 epoxy resin based adhesive for normal applications.

    Sikadur 30LP is an epoxy resin based adhesive for elevated temperatures during application and / or service, however lead times do apply call your local Sika office for further information.

    USES:

    Sika® CarboDur® M suitably experienced and trained specialist contractors.

    Sika® CarboDur® systems are used to improve, increase or repair the performance and resistance of structures for:

    Increased Load Carrying Capacity:

    • Increasing the load capacity of floor slabs, beams and bridge sections
    • For the installation of heavier machinery
    • To stabilise vibrating structures
    • For changes in building use

    Damage to structural elements due to:

    • Deterioration of the original construction materials
    • Steel reinforcement corrosion
    • Accidents (Vehicle impact, earthquakes, fire)

    Improvement of serviceability and durability:

    • Reduced deflection and crack width
    • Stress reduction in the steel reinforcement
    • Improved fatigue resistance

    Change of the structural system:

    • Removal of walls and/or columns
    • Removal of floor and wall sections to create access / openings

    Resistance to possible events:

    • Increased resistance to earthquakes, impact or explosion etc.

    To repair design or construction defects such as:

    • Insufficient / inadequate reinforcement
    • Insufficient / inadequate structural depth

    CHARACTERISTICS / ADVANTAGES

    ▪ Combination of very high strength and high stiffness

    ▪ Non-corroding

    ▪ Excellent durability and fatigue resistance

    ▪ Unlimited lengths, no joints required Low system thickness, simple execution of plate intersections or crossings

    ▪ Easy transportation (rolls) Lightweight, very easy to install, especially overhead (without temporary support)

    ▪ Minimum preparation of plate, applicable in several layers

    ▪ Smooth edges without exposed fibres as result of production by pultrusion

    ▪ Extensive testing and approvals available from many countries worldwide

    Call FCS Concrete Repairs for all your structural strengthening requirements.

    Re-Certification of our Integrated (Quality) Management System

    October 22nd, 2019 Posted by Uncategorized 0 thoughts on “Re-Certification of our Integrated (Quality) Management System”

    FCS Concrete Repairs’ Integrated (Quality) Management System latest three yearly Re-Certification Audit has been successfully completed and FCS Concrete Repairs can continue to proudly display our Quality ticks and assure our customers that we will continue to provide a quality service.

    Has the World’s Largest Concrete Mass Slowed the Earth’s Rotation and Tilted it’s Axis?

    October 22nd, 2019 Posted by Uncategorized 0 thoughts on “Has the World’s Largest Concrete Mass Slowed the Earth’s Rotation and Tilted it’s Axis?”

    The answer according to the experts is yes!

    The Three Gorges Dam in China is the world’s largest concrete mass.

    Length: 2,335 metres

    Height: 181 metres

    Weight of Steel Reinforcement: 463,000 tonnes

    Weight of Concrete: 40,000,000 tonnes (16,000,000 m3)

    Weight of Water: raised 35,000,000 tonnes of water 175 metres above sea level.

    NASA have calculated that:

    • the length of a day has increased by six hundredths of a microsecond
    • the North and South Poles have moved by 2 centimetres

    NASA’s reasoning is that the total mass of the dam is large enough to:

    1. tilt the Earth’s axis, and
    2. slow the Earth’s rotation.

    An Interesting Feature of the Three Gorges Dam:

    The Dam has A Ships Elevator.

    It can lift ships with a maximum displacement up to 3,000 tonnes and is designed to lift a total weight of 15,500 tonnes by up to 113 metres.

    How can this be achieved?

    Archimedes’ principle of displacement is the scientific answer.

    Archimedes

    Archimedes of Syracuse was a Greek mathematician, physicist, engineer, inventor, and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Generally considered the greatest mathematician of antiquity and one of the greatest of all time, Archimedes anticipated modern calculus and analysis by applying concepts of infinitesimals and the method of exhaustion to derive and rigorously prove a range of geometrical theorems, including the area of a circle, the surface area and volume of a sphere, and the area under a parabola.

    Archimedes‘ principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body’s displaces and acts in the upward direction at the centre of mass of the displaced fluid.

    In more simple terms, any floating object displaces its own weight of fluid.

    The Ship Lift Structure:

    The main components of the structure are four 169m high reinforced concrete towers.

    The four towers are built on a continuous foundation slab, directly on granite rock.

    Between the towers the steel ship chamber, which is 132m long, is suspended from 256 ropes that are connected with counterweights via 128 double rope pulleys at the tops of the towers.

    Each pair of towers on the long sides of the ship chamber is flanked by shear walls.

    The walls and towers are connected by coupling beams distributed evenly over the height.

    Two bridges between the towers are located above the ship chamber, one for the central control room and one for a visitor platform.

    The Step by Step Process:

    When a ship heads upstream, it first has to get into the fifth chamber.

    Close the fifth chamber and make the water level in fifth chamber the same with the fourth chamber.

    Then, open the gate between fifth chamber and fourth chamber and ship goes into the fourth chamber.

    Repeat this step in each chamber and the ship can cross the five chambers by passing six gates.

    And voilà, the ship exits from the top chamber and proceeds into the upper Yangtze River.

    Who designed the Ship Lift?

    Jointly designed by Chinese and German engineers.

    This is how it looks in action:

    https://www.youtube.com/watch?v=Uz0jLZBkx6I

     Video: Published by New China TV on 17 September 2016.

    The Three Gorges Dam is also a Giant Power Station:

    Three Gorges Dam is the world’s largest power station in terms of installed capacity of 2,500 MegaWatts.

    The dam is the largest operating hydroelectric facility in terms of annual energy generation, generating over 100 billion kilowatt hours in 2018.

    There are twenty-six rotating generators.

    These generators use Francis Turbines.

    This is one of the Turbine Rotors.

    The Three Gorges Dam is an amazing engineering feat and great credit must go to the Engineers and Builders and thousands of workers who created this enormous technically advanced concrete structure.

    CONCRETE STRUCTURES MAY REQUIRE CONCRETE REPAIR OVER TIME AS THE CONCRETE AGES.

    FCS CONCRETE REPAIRS ARE EXPERTS IN CONCRETE REPAIR AND LEAK SEALING.

    Your concrete repair project may not be as large as the Three Gorges Dam but nevertheless it is important to us. So please call for Advice and a Quote.

    What Is Elastomeric Concrete?

    March 12th, 2019 Posted by Blog, Concrete Repair, Uncategorized 0 thoughts on “What Is Elastomeric Concrete?”

    Elastomeric Concrete is a flexible 2-part polyurethane patching material mixed with aggregates and can be used as a filler in expansion joints which experience large movements.

    The properties which are most important for these materials are flexibility, elasticity, and bond strength.

    Flexibility and elasticity allow the material to absorb shock caused by traffic impacting on the extrusions.

    Bond strength to the adjacent surface is critical in all conditions, both wet and dry.

    Obtaining adequate flexibility and bond strength together in one material is difficult but has been achieved with this material.

    The key characteristics

    Elastomeric Concrete provides a flexible patch with excellent adhesion that will deflect as surrounding concrete expands and contracts and can resist heavy pressure before deflecting. The critical point is that Elastomeric Concrete allows itself to return to its original state after deflection.

    FCS Concrete Repairs has successfully used Elastomeric Concrete for repairing and patching concrete floors. This includes patching across expansion joints without the need for expensive joint reconstruction or major concrete removal.

    The following project photos illustrate the advantages of Elastomeric Concrete patching material:

    A Patch Across an expansion joint

    A Patch at the intersection of several expansion joints

     

    A Patch along an expansion joint

    A Patch at an entry threshold

    A Patch at a column base

    A Patch along an irregular crack

    RECENT PROJECT INVOLVING CRACK INJECTION

    March 12th, 2019 Posted by Uncategorized 0 thoughts on “RECENT PROJECT INVOLVING CRACK INJECTION”

    Description: Repair of Reservoir Tank.

    Elements: Crack Injection, Cathodic Protection and Waterproof Membrane

    Scope of Works

    External crack repair methodology:

    1. Mark out repair areas.
    2. Square cut to a minimum of 10mm
    3. Scabble back to sound concrete
    4. Expose corroding reinforcement
    5. Break out concrete to a minimum of 25mm behind bar.
    6. Grit blast reinforcing
    7. Replace corroded reinforcement if necessary
    8.  Rout non-moving cracks to minimum of 10mm
    9. Install anodes to steel reinforcement at 300mm centres
    10. Check continuity of anodes to steel
    11. Coat steel with primer
    12. Pre-soak concrete substrate
    13. Apply specified bonding agent to concrete only
    14. Apply specified render material to prepared cracks
    15. Re-apply any dried bonding agent
    16. Cure render material immediately after finishing each repair.

    Internal crack repair methodology

    1. V-grind out cracks to 25mm
    2. Brush specified waterproofing system into base of prepared crack
    3. Trowel apply specified mortar to re-profile crack
    4. Damp cure repair material with wet hessian for five (5) days

    Rehabilitation of Internal Floor and Wall

    1. Polymer Modified Membrane to be coated onto internal wall and floor of the Water Tank.
    2. The VersEseal range seals invisible and hard to find leaks in water storage systems with a non-toxic chemical-resistant coating.
    3. VersEseal may be used on already damaged water tanks or can seal new structures to extend the life of the tank or liquid storage structure, protecting metal from corrosion.
    4. Application of VersEseal’s Waterproof Membrane System is straightforward, environmentally safe and free from hazardous fumes.
    5. It can be applied in confined spaces without the heavy duty personal protective equipment that some products require.

    LRM Products VersEseal – Rapid Build

    Heavy-duty textured waterproof sprayable & brushable coating for surface protection

    VersEseal Rapid Build is a single component product that may be applied using a roller, squeegee or aggregate spray equipment. VersEseal Rapid Build is applied in thickness from 1.0 – 2.0mm.

    LRM Products VersEseal – Rapid Build is a fluid applied polymer modified emulsion and is recommended for use in a variety of harsh environments, chemically exposed areas, temperature variations and high traffic areas.

    VersEseal Rapid Build when cured fully adheres to the substrate to which it is applied, providing a flexible long wearing surface and is formulated for application by brush, roller, trowel or squeege.

    Applications include concrete repair, expansion joints, foundation sealing, plumbing applications, retaining walls, roof repair, sewage pump stations, water tank membranes, reservoirs, waste water storage, civil pipe joints, UV protection.

    Galvashield XPT

    Embedded galvanic anodes are designed to provide localized corrosion protection.  When placed at the appropriate spacing along the perimeter of concrete patches or along the interface between new/existing concrete, the anodes mitigate the formation of new corrosion sites in the existing concrete in adjacent areas.

    Description

    The Galvashield XP range of embedded galvanic anode units utilise an innovative zinc anode core design surrounded by an enhanced formulated cement-based mortar to provide corrosion mitigation to reinforced concrete structures. The anode units are alkali-activated (Type A) with an internal pH of 14 or greater to keep the zinc active over the life of the anode while being non-corrosive to reinforcing steel. The anode units utilise 2G Technology™ to provide higher current output. Once installed, the zinc anode corrodes preferentially to the adjacent reinforcing steel, thereby providing galvanic corrosion prevention or corrosion control.

    Applications

     Mitigates incipient anode formation (halo effect) in patch repair applications

     Bridge widening and other structure modifications

     Slab replacements, expansion joint repairs and other interfaces between new and existing concrete

     Repair of prestressed and post-tensioned concrete

     Chloride contaminated or carbonated concrete

    Advantages

     Proven technology – Galvashield has an extensive 10 year track record in the field

     Type A anode – alkali-activated to maintain activity of zinc while being non-corrosive to reinforcing steel

     Cast zinc core – provides high anode utilisation in addition to a secure long-term connection between the zinc and the lead wires

     Integral steel lead wires – allows for quick and convenient anode installation. Provides dependable steel-to-steel contact with no intermediate materials such as galvanising (which can corrode over time) that may compromise the long-term electrical connection

     BarFit™ design – grooved edges on Galvashield XP2 and XP4 anode units assist with secure anode placement

     Economical – provides localised protection where it is needed the most, at the interface of the repair and the remaining contaminated concrete

     Versatile – can be used for both conventionally reinforced and prestressed or post-tensioned concrete

     Low maintenance – requires no external power source or system monitoring

     Long lasting – 10 to 20 year service life* reduces the need for future repairs. *As with all galvanic protection systems, service life and performance is dependent upon a number of

    factors including reinforcing steel density, concrete conductivity, chloride concentration, humidity and anode spacing.

    Galvanic Anode Installation

    1. Install anode units and repair material immediately following preparation and cleaning of the steel reinforcement.
    1. Galvanic anodes shall be installed along the perimeter of the repair or interface at a spacing of (x mm) as specified on the drawings. Anode spacing will vary with changes in the reinforcing steel density, the level of chloride in the structure and the corrosivity of the local environment, etc. 
    Note to Specifier:  Typical spacing for Galvashield XPT ranges from 430-610 mm.  The maximum anode spacing guidelines can be found on the Galvashield XP data sheet.  Anode spacing should be adjusted for aggressive service conditions or for an extended anode service life.
    • Provide sufficient clearance between anodes and substrate to allow repair material to encase anode. 
    • Secure the galvanic anodes as close as possible to the patch edge using the anode tie wires. The tie wires shall be wrapped around the cleaned reinforcing steel and twisted tight to allow little or no free movement.
    1. If less than 25 mm of concrete cover is expected, place anode beside or beneath the bar and secure to clean reinforcing steel.
    • If sufficient concrete cover exists, the anode may be placed along a single bar or at the intersection between two bars and secured to each clean bar.
    • If repair materials with resistivity greater than 15,000 ohm-cm are to be used or the resistivity is unknown, create a conductive grout bridge between the anode and the substrate. Pack Galvashield Embedding Mortar to cover minimum area of 100mm in diameter between the anode and the substrate concrete ensuring no voids exist.  
    • Electrical Continuity
    1. Confirm electrical connection between anode tie wire and reinforcing steel by measuring DC resistance (ohm,W) or potential (mV) with a multi-meter. 
    • Electrical connection is acceptable if the DC resistance measured with multi-meter is less than 1 W or the DC potential is less than 1 mV.
    • Confirm electrical continuity of the exposed reinforcing steel within the repair area. If necessary, electrical continuity shall be established with steel tie wire.
    • Electrical continuity between test areas is acceptable if the DC resistance measured with multi-meter is less than 1 W or the potential is less than 1 mV.

    FEATURED PRODUCTS: Fosroc® Nitofill LV

    May 24th, 2018 Posted by Uncategorized 0 thoughts on “FEATURED PRODUCTS: Fosroc® Nitofill LV”

    Product Description

    Low viscosity, dual cartridge, epoxy crack-injection system

    Uses

    Nitofill LV is designed for injecting cracks in concrete and masonry where there is a need to consolidate a structure or exclude water and air from contact with the reinforcement.

    Nitofill LV is a high strength, low viscosity resin injection system and provides excellent bond to concrete and masonry.

    The Nitofill LV system is ideal for small scale repairs on site and is also suitable for insitu or precast concrete elements.

    Advantages

    • n Suitable for structural crack repairsn Low viscosity allows penetration into the finest cracksn Non-shrink, adheres with no loss of bond

      n System includes everything necessary to complete the crack injection

      n Convenient to use, disposable cartridge pack contains both base and hardener

      n Cost effective and efficient repair

    FEATURED PRODUCTS: Sikadur®-52 LV

    May 24th, 2018 Posted by Uncategorized 0 thoughts on “FEATURED PRODUCTS: Sikadur®-52 LV”

    PRODUCT DESCRIPTION

    Sikadur-52 is a low viscosity, free flowing and fast curing injection resin and primer/coating based on a 2 component solvent free epoxy resin; ideally suited to a wide range of building and civil engineering applications where highly penetrative material is required.  It is available in two grades, Normal and Long Potlife for moderate and high ambient temperatures, respectively.

    Uses

    Sikadur-52 may be used to inject and fill cracks between 0.2 – 5 mm wide in a wide variety of constructions applications.

    Sikadur-52 does not shrink on curing and forms a rigid, high strength product which exhibits excellent adhesion to most construction materials enabling the restoration of structural adequacy to columns, beams, foundations, decks and water retaining structures.

    Due to its highly penetrative nature Sikadur-52 is ideally suited for application as a primer beneath Sikadur epoxy mortars or Sikafloor mortars and coatings on dense substrates.

    Sikadur-52 may also be used to stabilise weak and friable substrates.

    Special high strength grades can be made to order.

    ADVANTAGES

     Shrink free

     Insensitive to moisture during application, cure or whilst in service

     Applicable over wide temperature range

     Low viscosity

     Excellent adhesion to most building materials even when damp

     Proven in service

     High tensile and flexural strength

     Supplied in factory proportioned units

     High early strength  Chemical resistant

    FEATURED PRODUCTS: PRIME FLEX 900 XLV

    May 24th, 2018 Posted by Uncategorized 0 thoughts on “FEATURED PRODUCTS: PRIME FLEX 900 XLV”

    Product Description

    Prime Flex 900 XLV polyurethane resin is a low viscosity, hydrophilic resin that reacts with water and expands to form a closed cell, watertight foam. It is typically injected under pressure to seal actively leaking joints and cracks in concrete structures, including hairline cracks. This product is independently tested and proven to meet NSF/ANSI Standard 61.5 for contact with potable water.

    Recommended Uses

    • Injecting hairline cracks, expansion joints, wide cracks, pipe joints, or pipe penetrations
    • Sealing active leaks in above- or below-grade concrete structures
    • Oil-free oakum or open cell backer rod may be soaked in Prime Flex 900 XLV to create a watertight gasket

    Advantages

    • NSF/ANSI Standard 61.5 compliant for contact with potable water
    • Single-component. No catalyst or accelerators needed. Pump material straight out of the pail.
    • Extremely tough and flexible. Can expand and contract parallel to the crack in varying temperatures.
    • Up to 600% expansion (unconfined)
    • Low viscosity will penetrate tight cracks

     

    The Strength of the Surface of the Concrete Substrate and of the Adhesive are Critical Factors in the Use of Carbon Fibre Reinforced Polymers

    April 9th, 2017 Posted by Uncategorized 0 thoughts on “The Strength of the Surface of the Concrete Substrate and of the Adhesive are Critical Factors in the Use of Carbon Fibre Reinforced Polymers”

    Carbon Fibres have been developed for the aerospace industry which needed a material which combined high strength, high stiffness and low weight. In recent years the Construction Industry have recognised the potential of this material to provide solutions for problems associated with the strengthening of deteriorating infrastructure.

    BONDING MATERIAL

    When CFRP is used externally to strengthen concrete elements in a buildings, bridges etc the bond between the CFRP and the concrete substrate is critical.
    The strength of the adhesive and the degree of stress at the interface determine whether the CFRP delaminates and failure occurs. The shear strength capacity of the substrate material is therefore a major parameter of the interface region behaviour.
    In testing, the failure surface was located at the top of the substrate concrete just below the bond adhesive whereas the bond product itself provided the highest pull-off strength values. (International Journal of Adhesion and Adhesives 6 January 2005)
    The concrete substrate therefore must be pull-off tested to ensure that shear-tension failure of the concrete cover is not a factor and the recommended high strength adhesive must be used.

    INSTALLATION

    1. Surface preparation by sand or water blasting to expose course and fine aggregate surfaces.
    2. Bond pull-off tests of the concrete substrate.
    3. Measure the levelness of the prepared surface with a straight edge.
    4. Levelling mortar should be used if necessary.
    5. The following high strength structural adhesive is recommended by Sika for their product, Sika®CarboDur®reinforcement:

    Sikadur®30 epoxy resin is used to bond the CFRP to the concrete substrate and has a high early strength and a high tensile and flexural strength.

    IMPORTANTLY surface preparation, levelling of the substrate and the quality of workmanship are critical elements in the application of CFRP structural strengthening.

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