Issue 6 - June 2016
The Sprayed Concrete Association (SCA), one of the associations that comprises the Structural Concrete Alliance, is soon to release a new edition of its popular document, An Introduction to Sprayed Concrete.
The document, which aims to demonstrate the wide uses and versatility of sprayed concrete, describes the broad range of commonly used processes and materials available in the marketplace. It also offers best practice advice, explaining to the user to the best ways of carrying out these processes safely to produce a high quality end product.
Arranged in 16 chapters, the Introduction to Sprayed Concrete is designed to be used by industry professionals who require basic practical knowledge of sprayed concrete techniques and is not intended to be a comprehensive Specification or Standard.
It provides an introduction to material and process considerations including the properties & advantages of sprayed concrete; wet and dry processes; robotic equipment; surface finishes and constituent materials. It also discusses control issues such as health & safety; quality control & testing; training & certification; and design & specification; and provides a useful glossary of terms.
The guide encourages users to always specify an SCA member for advice, design, supply and application of sprayed concrete, explaining that SCA members have the training, experience and skills to ensure a professional approach and quality finish.
The document will soon be available for free download from the SCA website, www.sca.org.uk; or a hard copy can be purchased for £20 For further information or to pre-order a copy email:firstname.lastname@example.org.
Westone Bridge at Weston Favell in Northamptonshire has recently undergone a 26-week programme of complete refurbishment by Makers Construction.
This multi-section pedestrian footbridge, which crosses above the busy A43 dual carriageway, comprises eight sections, with the largest single section 17.5m long.
During a total 4-lane highway closure and traffic diversion over three consecutive nights, six of the bridge’s steel sections were lifted off and taken to an off-site location where they underwent complete refurbishment and structural enhancement.
Following the removal of six of the bridge’s steel sections, the remaining 13 in-situ reinforced concrete piers had to undergo substantial concrete repairs having not been afforded protection from the elements by any protective coatings since their original construction. Large areas of concrete were broken away from the piers and, following surface preparation of the exposed corroding reinforcement, shuttering was built around the tops of the piers and the concrete repaired using Sika’s pre-bagged Armorcrete flowable concrete repair mortar.
The exposed reinforcing steelwork on many of the vertical faces of the supporting columns were also repaired using hand-placed, Sika’s Monotop concrete repair mortars.
Once repaired – and following the application of Sika’s Ferrogard 903 migratory corrosion inhibitor as part of the corrosion management strategy for the concrete elements, Sika’s 2mm thick Monotop surface levelling mortar was applied to add additional theoretical concrete cover, as well as to mask the repaired areas and provide a suitably smooth surface for the final application of Sika’s 550W elastomeric anti- carbonation coating.
During the regeneration of balconies and walkways at a housing block in Dunfermline, Scotland, Sika’s fast curing Sikafloor® Pronto flooring system ensured the repair works could be carried out quickly, efficiently and with minimal impact on residents during the harsh winter weather.
As part of improvement works by Fife Council to upgrade its ageing housing stock, John Douglas Home in Golfdrum Street was externally refurbished with new waterproofing systems for the roofs, balconies and walkways. For a visually attractive, watertight and non-slip finish for the walkways, as well as a fast-curing application to minimise downtime, Sikafloor® Pronto provided an ideal solution for the contractor and client.
The fast application process allowed the refurbishments to be carried out at John Douglas Home with the minimum of disruption to residents. Sikafloor® Pronto can also be applied in a wide range of climatic conditions and is specifically suitable for lower temperatures, making it an ideal solution for the vagaries of the harsh Scottish winter weather
VolkerLaser delivered major strengthening works to Reading Bridge, a historic spandrel arch structure which forms an essential part of the strategic transport network for the Berkshire area.
Supporting a three-lane highway and two footways over the River Thames, Reading Bridge was built using an early form of reinforced concrete during the latter part of the 19th century. Receiving only minor works since its opening in 1923, the structure was in need of major strengthening and associated civils works in order to extend its longevity.
The use of carbon fibre strengthening on the project was innovative. Thin, strong and flexible, carbon fibre plates can be designed and installed to provide a cost effective solution while not detracting visually from the original design of the structure. These plates were applied to the soffit of the bridge deck and beams, enabling an increase in its carrying capacity. Spandrel columns were also carbon wrapped to assist with the management of the constraints of the loadings and the vehicles above, mitigating risk to the overall delivery of the project.
The VolkerLaser team maintained a proactive approach throughout, ensuring planned closures and technical issues were addressed regularly in order to maintain the smooth running of operations.
Completed on time and to a high standard, the reinforced and stabilised Reading Bridge will now offer a safer, more durable and trusted route for the 24,000 vehicles that rely on this vital transport link every day.
With concrete repairs the need for rapid reinstatement is often paramount, particularly within trafficked areas where massive disruption can occur during maintenance work.
Fosroc’s fast-setting concrete pavement and floor repair mortars – Patchroc GP and Paveroc – can now be matched with an equally fast cure sealant Thioflex 555, which has been developed to ensure speedy return to service.
Fosroc® Thioflex 555 is available in two grades and reduces downtime for resealing work. Hand Grade provides for a 12 hour return to service at 10 degrees C; while Machine Grade can offer a1 hour return to service at 10 degrees C. An important part of the system is Primer 7E, which can be spray or brush applied and gives fast development of a superior bond that ensures any early slab movement will be safely accommodated.
The machine grade Thioflex 555 has been successfully used at Dublin Airport where the sealing work was completed quickly, avoiding potential flight disruptions. The Dublin Airport Authority were completely satisfied with the Thioflex 555 solution applied at this airside project at Pier 2 and are now using the system in other contracts at the airport. The hand grade version has also been trialled during maintenance work to a large parking area.
Thioflex 555 is compliant to EN 14188-2 and BS 5212 and offers durable, long term performance, reducing maintenance costs providing a complete solution to concrete pavement repairs.
Balvac recently carried out specialist works for Carillion Morgan Sindall JV at the A6 to Manchester Airport Relief Road (A6MARR) project near Stockport.
As part of the project, a new bridge was constructed to carry the Hazel Grove to Buxton railway line over the new A6 road. This was slid into its final position during Easter 2016.
Balvac’s specialist MacAlloy Bar installation, stressing and grouting expertise was utilised to ensure the bridge slide was a success.
Balvac provided early contractor input to the project, including trial grouting operations, in advance of the possession works. Balvac’s work included: temporary clamping of the steel deck to the cill beams to enable the bridge assembly to be moved into position; installation of 32 No. stainless steel 50mm diameter MacAlloy Bars through the cill beams into the pile caps, including stressing and annular grouting; epoxy grouting to the zones between the pile caps and the bridge cill beams; and epoxy grouting to the permanent bridge bearings.
The new rail bridge is one of the longest single span plate girder bridges of this type in the country. Weighing over 400 tonnes, the steel bridge beams, along with approximately 1,000 tonnes of reinforced concrete cill beams, had to be lifted and slid into place using special purpose modular transport units. For further information or to discuss where Balvac’s specialist expertise can be used on your project, please contact Adrian Couper, Technical Manager, Balvac.
To mark its 60th anniversary, Concrete Repairs Ltd (CRL) has launched a completely new website in a format which is fully responsive for all viewing devices. The site covers all the business sectors in which the company operates and the services provided. Each sector and service has supporting case studies and brochures to download in pdf format.
The Company page gives you the opportunity to learn more about CRL’s history, business services, and meet the Directors. CRL is proud of the service it provides and you can see some of its Client Testimonials on this page. There is also the opportunity to join their successful team!
The News page will keep you up to date with all the latest announcements such as new contracts, business awards and industry safety information.
Finally on the Contacts page you can decide which of our five regional offices is closest and meet the Regional Manager responsible.
Please visit the website www.crl.eu.com and find out more about how we can help your business.
Freyssinet Ltd has conducted concrete repairs and installed an impressed current cathodic protection (ICCP) system to protect the Low Road Bridge in Spalding Lincolnshire, which carries the road over the Coronation Channel. The Coronation Channel flows north from Crowland, through Spalding and out to the Wash.
The contract, awarded by Kier MG, comprised of concrete repairs to remove the delaminated/spalled concrete and the supply, installation, and commissioning of an ICCP system developed by Freyssinet’s sister company Corrosion Control Services Limited (CCSL). The works were installed by Freyssinet and technical supervision was provided by CCSL.
All works were undertaken beneath the deck and were carried out from a pontoon in the Coronation Channel, as the Spalding river taxi prevented scaffold being erected. The bridge remained open to traffic throughout the works.
Once concrete repairs were completed, an ICCP system was installed. Force Technology/CPI discrete anodes installed into the soffit of the deck were selected.
The structures which were repaired and protected included the four halving joints; each joint was divided into two separate anode zones.
The remote monitoring and control system selected was the durApower 4+8 system developed by Force Technology/CPI in conjunction with CCSL.
The ICCP system was commissioned in April 2016 and will be monitored for a period of 56 weeks by CCSL.
Impregnation of post-tensioning tendons, a recent advancement in corrosion mitigation of grouted post-tensioning steel, offers a promising solution to protect both new and existing post-tensioning tendons from the effects of high voiding, bleed water, sulphates, and chloride-induced corrosion, says Vector Corrosion Technologies.
The system utilises the naturally occurring interstitial spaces between the wires of seven-wire strands to transport a formulated low-viscosity, dual-acting, hydrocarbon-silicon-polymer resin that displaces moisture, forms a protective barrier on exposed steel surfaces, and impregnates the surrounding grout to form a barrier to moisture and oxygen
Corrosion testing carried out on impregnated samples produced positive results with a 94.7% reduction in corrosion rate in samples with 4.5% grout voids. In addition, the treatment improved the corrosion resistance of properly grouted post-tensioning strands, a result that demonstrates the benefit of the impregnation process as a proactive corrosion protection treatment for newly constructed post-tensioned bridges.
Post-tensioned concrete is a well-accepted construction technique that offers appreciable benefits in bridge design, construction, and appearance. Post-tensioned bridge tendons are normally bonded with cementitious grout after tendon stressing. In addition to bonding the strands in place, the cementitious grout provides an important function in the durability of the structure by protecting the post-tensioning tendons from corrosion. Modern grouts have improved performance, but problems still remain in the form of grout voids, segregated grout, soft grout, presence of a high level of sulphates, and chloride-contaminated grout.
Vector Corrosion Technologies are a world leading supplier of corrosion mitigation products and services for reinforced concrete. Vector’s expertise has been developed over 50 years in delivering innovative solutions to its clients.
Leading independent distributor of construction chemicals, Resapol, has entered into the market in Scotland with the opening of a new sales depot. Aimed at improving their service and subsequent delivery coverage, the new depot increases its total number of UK sales branches to eight.
The company depots work closely together controlling and sharing stocks in order to ensure sites nationally can be serviced with ease and speed. Communication between depots enables swift recognition of the individual customer needs and requirements.
Specialising in the distribution of quality construction chemicals, including an extensive range of concrete repair materials, Resapol takes pride in its delivery service and realises the importance of being able to deliver goods on time, every time, anywhere in the UK.
Based in Glasgow the new sales depot is situated centrally, allowing the branch to improve Resapol’s great service to the entire country. The new Glasgow team comprises: Alexander Clark, Branch manager with Jim Johnston, Technical Sales and Scott Geddes.
The depot can be contacted at: Unit 5, Houston Place, Kingston Bridge Trading Estate, Glasgow, G5 8SG; Sales & Technical tel: 01414 290482; fax: 01414 293950; email: email@example.com.
Resapol also has further plans for expansion in the coming months, including a new location for their Leeds depot and Head Office. For more information please check out their technical website at resapol.com, or keep up to speed with everything Resapol on twitter, @resapol.
The Bon Accord Shopping Centre is the second largest shopping centre complex in Aberdeen and is served by a number of car parks providing a total of 1,700 parking spaces.
USL StructureCare and sister company and manufacturer Nufins, have recently begun a large and prestigious £2m concrete repair project to the 700 space Loch Street multi-storey car park. This has been suffering from extensive concrete deterioration and high levels of chloride contamination for years.
The 35 week project sees USL breaking out repairs to decks and soffits, which will then be reinstated using the Nufins range of concrete repair products. Due to the high levels of chloride contamination in the decks, and in order to arrest the corrosion of the embedded steel reinforcement in only 7 days, USL are also installing approximately 22,000 No. hybrid dual technology anodes by CPT Ltd into many of the deck areas.
Once repairs are all complete, USL's DeckProtect+ coating system will be installed to deck areas to protect against further water/salt ingress and to improve aesthetics via the introduction of a coloured high performing and robust lightweight waterproofing.
All other exposed areas of concrete will be treated with Nufins Covercrete anti-carbonation paint to protect against future carbon dioxide ingress.
Hybrid corrosion protection is a UK invention applied as a remedial measure to reinforced concrete structures suffering attack from chloride salts and/or carbonation. It consists of a brief impressed current treatment (typically 1 week) followed by galvanic protection.
A feature unique to the electrochemical treatment of concrete is that a current may alter the environment at the reinforcing steel sufficiently such that, were the current removed entirely, the steel would return to the passive state that was present prior to the initiation of corrosion. This feature forms the basis for the temporary impressed current phase of the hybrid treatment known as DuoGuardTM.
A subsequent galvanic phase is applied using the same anode system. The galvanic current output is responsive to the aggressive nature of the environment and is higher in hot wet conditions where more protection is needed. The principal benefit of the treatment over other powerful electrochemical treatments is that there is no requirement for the client to maintain a power supply.
The treatment was first applied in 2006 to two bridges in Northumberland where monitoring has demonstrated the long-term effectiveness of the system. Hybrid corrosion protection now has a ten-year track record and has been widely used throughout the world.
Developed in-house by Cathodic Protection Co Ltd engineers, the Switch Mode Power Supply (SMPS) is an ideal solution for low power applications, particularly concrete cathodic protection (CP) systems. It has proven to be a cost effective, reliable and low maintenance CP power supply, and features surge protection as standard and the option of local and/or remote control.
It features an AC supply (90-260V, 1ph, 50-60Hz) with a power factor >0.9, and a 144W DC output with a dual range at 24V 6A and 12V 12A. Air cooled, it is built to suit all environments, safe or hazardous, including marine, desert, tropical and Arctic.
The enclosure can be manufactured to a client’s particular specifications, and the unit, which has a microprocessor based control board, has a control resolution of 1mA and 1mV across the output range. It has digital controls and metering, with constant voltage, constant current and auto potential control as standard.
An additional 8 channel monitoring module is available in the same form factor, which is able to daisy chain and monitor an unlimited number of reference electrodes with outstanding precision at less than 1mV.
The unit is fully compatible with CPCL’s Remote Monitoring and Control Systems and is compliant with BS EN 12696:2012. No matter what options customers choose, they can be assured of CPCL’s international capability and support, with over 60 years’ experience in the market.
Places are still available on the Structural Concrete Alliance free to attend regional Continuing Professional Development (CPD) seminars this Autumn.
Designed to provide delegates with an introduction to Structural Asset Protection and Repair, these half-day events offer an introduction to corrosion as well as techniques for repair, protection and strengthening.
Presentations are varied to reflect the region in which the seminar takes place but include: An introduction to corrosion; An overview of electrochemical systems; Concrete repairs and coatings; Carbon fibre strengthening; Introduction to sprayed concrete; and Inspection of reinforced buildings & structures.
Three CPD seminars are scheduled for late 2016:
For those unable to make the seminars, the Alliance also offers CPD presentations which can be delivered on-site to interested parties.
To book call 01420 471619 or email
The Structural Concrete Alliance publishes a quarterly E-Bulletin providing the latest industry updates and news from members of the CRA, CPA and SCA, as they occur.
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.
The Corrosion Prevention Association represents consultants, contractors and manufacturers working in the field of corrosion prevention for reinforced concrete and masonry encased steel.
Sprayed Concrete Association (SCA) represents leading contracting and manufacturing companies engaged in sprayed concrete.Tweets by @SCAlliance3