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Structural Concrete Alliance E-Bulletin

Issue 3 - April 2015

Alliance issues new technical guidance

AllianceThe Structural Concrete Alliance has released several new guidance documents on the repair, maintenance and protection of concrete structures.

The Alliance, which brings together the Concrete Repair Association (CRA), Corrosion Prevention Association (CPA) and Sprayed Concrete Association (SCA), has recently added to its library of guidance documents with the publication of three new Technical Notes.

A new CRA document offers advice on Coating and protecting concrete in accordance with BS EN 1504; while the CPA has issued guidance on the use of cathodic protection systems in the form of Technical Note 22: Cathodic protection for buried & immersed structures and Technical Note 23: Cathodic protection for new structures.

Available for free download from the CRA website, www.cra.org.uk, Coating and protecting concrete in accordance with BS EN 1504 explains the mechanisms for concrete deterioration and offers the latest advice on available materials and coating application methods.

The CPA’s Technical Note 22 offers advice on Cathodic protection for buried & immersed structures. Although such structures can be protected using anode systems, the document states that protection can often be more economically provided using the cathodic methods regularly used to protect buried or immersed steel structures.

Meanwhile, Technical Note 23 Cathodic protection for new structures highlights the increasing use of such systems for new structures in particularly corrosive environments, or where longevity and guaranteed durability are of particular importance.

Both CPA documents are available for free download from the CPA website, www.corrosionprevention.org.uk

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Cemplas focuses on car park refurbishment and care

CemplasCemplas Waterproofing and Concrete Repairs Ltd is one of the UK’s leading independent car park specialists, renowned for high quality, affordable and reliable service for owners, asset managers and parking operators.

As part of the company’s programme of continued expansion it has appointed Wayne Madge as Business Development Manager with a brief to maximise direct business opportunities in the car park refurbishment market where he has extensive experience.

These developments, together with an understanding of the basic principles of car park deterioration, is of paramount importance in Cemplas's ongoing commitment to car park refurbishment and care.

Cemplas recognises that every car park structure is unique and will require a unique repair strategy. This may be to fulfil a DDA or Health and Safety requirement, to comply with an obligation to repair, or form part of a Life Care Plan initiative.

Operating as Principal Contractor alongside Asset Management teams, Building Surveyors and Engineers we ensure that the client’s requirements are fully understood and interpreted in a proactive, bespoke and cost effective manner.

A new Car Park brochure is available to download from the Cemplas web site together with a new Specialist Services brochure, and a new Concrete Testing methods brochure.

Current Business Development Director Paul Stacey moves to the role of Commercial and Marketing Director.

To view previous case studies of specialist works undertaken by Cemplas, please visit our website.

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CRL gives new life to Drewstead Bridge

CRLConcrete Repairs Ltd (CRL) have recently completed the repairs and installation of a cathodic protection system on the Drewstead Road Bridge in Streatham Hill, London. The bridge which carries the B221 across the main railway line is a significant transport route for Lambeth, with bus routes, commuting pedestrians, heavy goods and light vehicles constantly crossing the bridge. The bridge, built in 1968, comprises precast, prestressed concrete bridge beams spanning the railway lines, supported by two sets of four circular columns and a crosshead beam.

In 2012, it became evident that repairs to the superstructure and supporting columns and crosshead beams were required, and in 2014 the bridge underwent a large-scale refurbishment to address problems and extend the life of the structure.

Working with Free4M Consulting, a programme of testing by CRL Surveys determined the extent of the problem and enabled a suitable repair option to be presented to the client. The agreed solution consisted of a combination of concrete repairs, with an impressed current cathodic protection (ICCP) system to the portal crossheads.

Hydrodemolition was used to first remove all loose, spalling concrete and to get behind the reinforcing, with the repairs being carried out using a combination of hand placed material, and a poured/cast micro-repair concrete. The cathodic protection system, a mesh and overlay was then installed over the entire area of the crosshead beams.

Early contractor involvement, a proactive client and a forward-thinking engineer ensured the works were completed on time, to budget and to the client’s satisfaction.

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Sika gives facelift to tower block

SikaGlobal building product manufacturer Sika offered the perfect regeneration solution for the refurbishment and long term protection of Vittoria Court, a 14 storey concrete tower block in Birkenhead.

Vittoria Court in Birkenhead is one of eight tower blocks on the Wirral being upgraded as part of a £32 million refurbishment programme for Magenta Living. With the intention of repairing and protecting concrete surfaces and smoothing out the existing pebble dash, the specification included the Sika® MonoTop® repair system, and the anti-carbonation coating Sikagard®-675W.

Construction Techniques Ltd applied Sika® MonoTop® – a cementitious two-component system which consists of polymer modified mortars – to smooth out the imperfections and to provide a cost effective solution ready for overcoating. With a good resistance to water and chloride penetration, it will help to protect the building’s concrete exterior from future damage.

To provide an overall layer of protection and in order to provide a striking design, Sikagard®-675W ElastoColor was applied to the concrete facade. Used to aesthetically enhance concrete substrates and particularly suited as a final protective coating for facades, the anti-carbonation treatment provides a high quality yet economical water-based, acrylic coating to protect against weathering and ageing

Sika‘s concrete repair and protection solutions are designed to rehabilitate and restore concrete surfaces back to their original quality. Concrete repair mortars, anti-corrosion coatings, corrosion inhibitors, reinforcement corrosion protectors and the full Sika® Galvashield® range of embedded galvanic anodes make up the extensive Total Corrosion Management range that Sika offers.

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Structural Renovations Ltd launches a new responsive website

Structural RenovationsStructural Renovations Ltd has launched a brand new responsive website at: www.structuralrenovations.co.uk.

The new site has interesting news stories and case studies and is complemented by its Twitter feed @SRL_London.

It also offers details of its wide range of services including survey and advice, concrete repair and protection, waterproofing, composite strengthening and masonry repairs.

Structural Renovations Ltd has extensive experience in the health, education, governmental, commercial, residential and infrastructure sectors, working closely with consulting engineers, building surveyors and architects. Its services are frequently required on structures of a listed status, where it is able to assist in replicating various details to satisfy conservation bodies, such as English Heritage.

The site is regularly updated and visitors can register for a newsletter to keep up to date with latest developments. Information is provided on projects as diverse as Admiralty Pier in Dover, Chelsea Football Club, Metropolitan Wharf & the Barbican Estate.  The site’s contacts page has links to all members of staff, who will be pleased to receive your enquiries.

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Freyssinet protects Prickwillow Bridge

FreyssinetFreyssinet Ltd has conducted concrete repairs and installed an impressed current cathodic protection (ICCP) system to protect the Prickwillow Bridge in Cambridgeshire which carries the B1382 road.

The contract, awarded by Skanska Construction UK Ltd, comprised of concrete repairs to remove the delaminated/spalled concrete and the supply, installation, and commissioning of an ICCP system developed by Atkins/Cambridgeshire Highways. The works were installed by Freyssinet and Corrosion Control Services Ltd (CCSL)
All work beneath the deck was carried out from a pontoon in the river Lark as river traffic prevented scaffolding being erected. The bridge was closed to motor traffic while work was carried out on the top deck.

Once repairs were completed an ICCP system was installed. This consisted of two anode types, Chemical Newtech discrete anodes installed into drill holes and Chemical Newtech ribbon anode mesh installed into saw cut chases.

The structures repaired and protected comprised the east and west halving joints; anodes were installed into the top of the deck, the deck soffit, and the adjacent beam ends, each joint was divided into five separate anode zones. The remote monitoring and control system was developed by Remco Systems in conjunction with CCSL. The ICCP system was commissioned on the 10th November 2014 and will be monitored for a period of 56 weeks by CCSL.

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Makers repairs Merrion Centre car park

MakersBuilt in 1964, the 900-space Merrion Centre car park – owned & operated by Citipark – was the first multi-storey to be built in Leeds.

With the passage of time, it had developed an extensive range of defects and has recently undergone extensive concrete repairs, corrosion management, structural strengthening and deck waterproofing. 

This extensive package of specialist works was carried out by Makers Construction as part of a 48-week, £8.4m internal and external refurbishment programme managed by GMI Construction.  

In the largest carbon fibre strengthening project in Europe, 22km of Sika Carbodur plate was required to strengthen deflecting reinforced concrete beams. The project also included the drilling of 37,000 holes into which Sika’s AnchorC carbon fibre ropes were inserted and chemically bonded. 28,000m2 of SikaWrap carbon fibre matting was applied to the soffits of the parking decks.

“The project was logistically challenging given that we were on a very ambitious programme and were only allowed to take up 30% parking capacity at any one time with a key pre-requisite being to keep the car park operational at all times throughout the contract.” comments Graeme Middleton, Business Development Manager at Makers.

“You have the dual challenge of providing a safe working environment not only for your own workforce but also members of the public who are coming and going, using the car park whilst you are working.”

Makers were chosen as the most suitable contractor to carry out the works given their extensive experience in structural and car park refurbishment.

For further information, please contact Graeme Middleton g.middleton@makers.biz

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Saint-Gobain Weber in Brighton Marina pilot

WeberSaint-Gobain Weber’s high performance concrete repair products have been specified in a major pilot maintenance project at Brighton Marina - the largest manmade marina in Europe.

Substantial breakwater structures built in 1977 were formed by open bottom precast concrete caissons founded on concrete plugs.  The harsh environment has prompted a continuous monitoring of the structural and material integrity of the breakwaters.

A trial was set up to determine the validity and implementation process of installing a cathodic protection (CP) system to protect, and extend, the performance duration of the steel reinforcing within the concrete structure.

The pilot scheme has been undertaken by Concrete Repairs Limited (CRL) and Saint-Gobain Weber concrete repair products were specified as an integral part of this package. Once the CP mesh was successfully connected to the reinforcing steel, weber.cem spray DS was used to form a strong, protective coat over the mesh and wiring.

Ben Lawson, Senior Contract Manager at CRL explained, “This was a complex project but a very worthwhile one. Now the initial trial is over, we will analyse the procedures and refine the methods for when the main programme commences.

We specified Weber products from past and very satisfactory experience, as well as for exemplary technical support.  The use of the weber.cem pyratop for the roadway cover screed meant that we could re-lay the surface in one day and this fast curing meant access for emergency vehicles was possible very quickly.”

For more information contact Saint-Gobain Weber on 08703 330 070, or visit our website.

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CPT protects Sherborne footbridge

CPTConcrete Preservation Technologies is treating ongoing corrosion-induced concrete damage on various structural elements of the Sherborne footbridge, which spans the river Irwell in Salford.

Of particular interest were 9 post-tensioned beams which exhibited visible corrosion damage to the ducts and tendons. Post-tensioned beams are particularly difficult to treat since standard cathodic protection methods have the potential to induce hydrogen embrittlement of the steel tendons which could lead to failure.

A corrosion survey of the structure (visual, hammer-tap, steel half-cell potential, chloride profiling and carbonation depth analysis) revealed significant corrosion-induced damage and areas at risk of future corrosion. The source of the damage was determined to be chloride salts from de-icing of the bridge, which had leaked through joints and cracks, contaminating the substructure.

A DuoGuard hybrid system designed to ISO 12696:2012 was used by CPT to halt ongoing corrosion and prevent future corrosion damage to the deck support beams, bridge piers and post-tensioned beams spanning the river.

The DuoGuard system was installed in phases to fit with the bridge refurbishment programme. The initial impressed current phase of the hybrid system applied to the post-tensioned beams was closely monitored and controlled before the system was switched to long term sacrificial mode.

The system has insufficient voltage to cause hydrogen embrittlement and offers a safe long term solution. IP66 rated termination enclosures were installed on the piers to allow ongoing steel corrosion rate monitoring.

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Fosroc holds back the ocean at Dawlish

FosrocDawlish made the headlines in February 2014 when parts of the railway line were swept away during severe storms. Structures in or near the sea require materials that are resilient enough to withstand the impact of heavy seas, as well as the additional risk of corrosion caused by sea salts.

Fosroc offers a range of solutions that provide protection in the marine environment, including precast admixtures; concrete repair products; and the use of joint sealants and surface coatings. Some of these solutions are currently being used in repairs to the sea wall at Dawlish.

Temporary sea defences were constructed by AMCO when the wall collapsed, and Network Rail has now awarded AMCO the contract to increase the freeboard to the Dawlish lower sea wall, which protects the railway line between Exeter St David’s and Newton Abbot stations.

The Dawlish sea wall scheme is using key products from Fosroc to assist in the reconstruction works including Conbextra UW – a free flow / pumped, non-shrink, cementitious grout which can be used underwater or in tidal zones where “wash out” would be a problem with conventional grouts. Fosroc’s specialist sealant Nitoseal PU12, designed for use in sea defence works, is being used to seal joints as it offers excellent adhesion under immersed conditions.

Fosroc has been on site frequently to assist AMCO in understanding the products and their usage and also to ensure the contractor team are comfortable in applying the products.

For further information contact Sandra Westbrook on 01827 265150

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Balvac repairs Anlaby flyover

BalvacBalvac has undertaken repairs to the Anlaby flyover, which carries the A1105 Anlaby Road, one of the main access routes into Hull City Centre and the KC Stadium. 

Constructed in the early 1960s, the 376m-long reinforced concrete structure was suffering with concrete delamination from years of severe saline attack caused by road salts.  In places, the condition of the concrete was so deteriorated that sections had fallen away, exposing the internal steel reinforcement.

Balvac was awarded the contract following a competitive tendering process and began the repairs in May 2014. In accordance with the client’s specification, Balvac carried out 36m³ of concrete repairs utilising the Sika range of materials which included Sika Armorex Armorcrete for the poured repairs, Sika Monotop 612 for the hand repairs and Sika Cem Gunite 133 for the spray applied concrete repairs.

Incorporated into the repairs were over 2,500 Vector Galvashield Anodes which provide cathodic protection against future reinforcement corrosion.  The concrete was additionally protected with the application to over 2,500m² of Sika Ferrogard 903 corrosion inhibitor, while Sika Guard 550 W, a protective elastomeric coating, was applied to 9,000m² of concrete surfaces. 

Over 1,000m of steel parapet railings were fully repainted and over 500m² of Tremco waterproofing applied to the pedestrian ramps.
Balvac worked through the winter months in difficult weather conditions, sequencing repairs to minimise temporary works. Pedestrian access was maintained, particularly during events at the KC Stadium.

Balvac maintained an excellent relationship with Hull City Council throughout the works, delivering  another quality structural refurbishment and repair project.

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Alliance launches new website

AllianceThe Structural Concrete Alliance has launched a new website which provides visitors with easy access to Alliance news and e-bulletins. The site also directs visitors to publications and training available from the individual associations which make up the Alliance.

The new website offers an introduction to the aims of the Alliance and provides details of its organisation and management. It offers all of the latest news from the individual associations that make up the Alliance, and an e-bulletin archive.

The new site provides direct links to the technical guidance documents produced by each association, helping visitors to navigate directly to the advice they require.

The site also provides details of upcoming events and training courses, including the dates of its free regional seminar programme.

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Concrete Repair Association

Formed in 1989, the CRA is committed to promoting and developing the practice of concrete repair and allied disciplines, as well as advancing education, technical training and health & safety matters in this specialist construction sector.

www.cra.org.uk

CORROSION PREVENTION ASSOCIATION

The Corrosion Prevention Association represents consultants, contractors and manufacturers working in the field of corrosion prevention for reinforced concrete and masonry encased steel.

www.corrosionprevention.org.uk

SPRAYED CONCRETE ASSOCIATION (SCA)

Sprayed Concrete Association (SCA) represents leading contracting and manufacturing companies engaged in sprayed concrete.

www.sca.org.uk

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