THE MAGAZINE OF THE CONCRETE SOCIETY Volume 54 June 2020 Issue 05
concreteVisit: www.concrete.org.uk
GRC stud frames Overlooked opportunity?
Training and education Bridge construction Benefits and evolution Temporary works The Modern Approach to Concrete Investigation and Testing
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NOT Testing via Ground Penetrating Radar (GPR) and Ultrasonic Tomography Post Tensioned Special Inspections (PTSI) Concrete Condition Surveys High Alumina Cement (HAC) Investigations Structural Load Testing and Monitoring Detailed Structural Investigation/ Ascertain as built details Alkali Silica Reaction Investigations
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RISQS iiii AlcumusSafi!'Contractot· Constructionline Cold Member defra AYA Contents
3 From the Editor 4 World News 6 Society News
Bridge Construction and Repair 8 Kilkenny CAS Bridge – connecting a city for the future Caroline Cavanagh 12 The most common concrete deterioration processes in bridges Kaveh Afshinnia 16 Technical Guide No 16 – Temporary Works for Concrete Bridges Jeremy Barnes and Nigel Hewson 18 Working around buildability challenges to deliver a concrete bridge Ilyass Meslek
Training and Education 20 Concrete field testing technician: ACI–ICT certification programme rolled out Edwin Trout and Raman Mangabhai 24 Looking to a zero-carbon future with Constructionarium Charlotte Ainsworth 28 The benefits and evolution of training Mike Threadgold
Durability/Aggressive Environments 31 The integration of sodium acetate in concrete for protection against extreme weather conditions Mazen J Al-Kheetan, Seyed Hamidreza Ghaffar and Mujib M Rahman
Glass-fibre-reinforced Concrete 34 GRC stud-frame construction – an overlooked opportunity Nikolaj Ringberg Brandt 38 Fantastic façades – GRC comes of age in the UK James Butler
40 Features List/Ad Index/Subscriptions
concrete magazine is produced in-house by The Concrete Society, The June 2020 cover a not-for-profit, independent membership organisation dedicated to Stud-frame construction is often supporting the use of concrete, the most widely used building material in overlooked when producing and the world. Cover Story installing glass-fibre-reinforced concrete (GRC), despite offering Established in 1966, and with members from around a superior solution. GRC with the world, The Society has built on its technical base embedded stud-frame construction to become a leading provider of information, serving offers savings both in substructure the needs of clients, architects, engineers, specifiers, costs and a heavily reduced mounting suppliers, contractors and users of concrete. time. A look at the case for stud- frame construction and the various Visit: www.concrete.org.uk systems for its installation. See page 34. (Photo: KUDIVANI Photography.) Follow concrete on Pinterest Go to pinterest.com/concretemag/boards, click on a board to view images from projects featured in current and past issues. Share images with Follow: @ukConcrete Find us on: others within the concrete community. THE CONCRETE SOCIETY is an independent membership organisation dedicated to supporting the use of concrete – the most widely used building material in the world.
Established in 1966, The Society encourages innovation and the exchange of knowledge and experience across all disciplines. The Society works through the co-operation of our members, who come from all sectors of the industry to exchange information and experience, and to enhance the performance, productivity and quality of concrete as a construction medium. Supported by the technical and administrative staff of The Society, our members collaborate to produce and disseminate state-of-the-art reports, recommendations and practical guidance.
The Society receives special support from the following:
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The Society is supported by a global community of 250+ Corporate and 500 individual members. www.concrete.org.uk FROM THE EDITOR
EDITOR: James Luckey Tel: +44 (0)1276 607158 [email protected]
EDITORIAL ASSISTANT: Helen Marney Tel: +44 (0)1276 607159 [email protected] Zero-carbon focus TECHNICAL ADVISOR: Richard Barnes While news bulletins are still full of stories concerning the topic du jour, let’s ignore the ‘elephant in the room’ and focus on industry matters that still need DESIGN: Darryl Killoran addressing when life returns to normal – whatever form that will take.
SALES REPRESENTATIVE: Fred Combe ne of the striking statistics over sector is already working from a position of Tel: +44 (0)20 3859 7097 the past three months is the strength (no pun intended), having worked [email protected] fact that the UK’s daily carbon diligently on its carbon cutting – and overall James Pembroke Media Ltd is O emissions fell by 36% during environmental impact and performance – The Concrete Society’s appointed lockdown (up to the end of April). With over decades. CO2 emissions from cement advertising sales agency. passenger vehicle usage cut so drastically production have fallen 25% since 1998, (down 60%), the UK’s biggest carbon especially impressive considering that SUBSCRIPTIONS MANAGER: emission source – transport – was clearly a domestic sales have increased by 29% since Val Goddard significant factor in the fall of CO2 levels. 2012. The embodied carbon of concrete is Tel: +44 (0)1276 607149 Those figures have given further impetus also on a long-term downward trend, being [email protected] to the push for 2050 carbon-neutral Britain, cut by 30% based on 1990 levels. concrete is published 10 times a year (2020) with the committee that is advising the Lest anyone be in any doubt, these are no and sent free to all Concrete Society members. Government on such matters insisting easy achievements. Carbon emissions from Annual prepaid subscriptions for 2020: UK £125, Europe £150, outside Europe £170 that the UK’s economic recovery after the cement production in the US, for example, (prices inc. p&p). Single copies and back issues: pandemic should be ‘green’. have increased by 20% since 1990. £15 (exc. p&p). The Committee on Climate Change But moving forward, clearly there will be (CCC) has put forward a six-point plan to far greater scrutiny and demands placed on THE CONCRETE SOCIETY rebuild the nation, while delivering a stronger, carbon-intensive industries. For the cement President: cleaner and more resilient economy. These and concrete sector to stay at the forefront of Deiniol Williams points include: using ‘climate’ investments the built environment, it will not be a time Managing Director: to support economic recovery and jobs; of resting on laurels but redoubling efforts Kathy Calverley mbe strengthening incentives to reduce emissions to improve performance. That will mean when considering tax changes; leading a constant analysis of how CO2 emissions The Concrete Society, shift towards positive, long-term behaviours; can be cut at every stage of the production Riverside House, 4, Meadows Business Park, Station Approach, Blackwater, and providing support for carbon-intensive chain, from clinker, cement and concrete to Camberley, Surrey GU17 9AB, UK sectors contingent on them taking real and construction and recycling. Tel: +44 (0)1276 607140 lasting action on climate change. Social distancing may be a longer term part Fax: +44 (0)1276 607141 While the Government has taken a baby of the ‘new normal’ but the task to close the e-mail: [email protected] www.concrete.org.uk step with its £2 billion investment last month distance on zero carbon has already begun. to boost healthier and greener transport Enjoy the issue! Printed by Bishops Printers activity (namely cycling and walking), it is the Portsmouth, Hampshire last of these CCC points that will have the © The Concrete Society, 2020 greatest impact on our industry. ISSN 0010-5317 The need for a subtle change in approach is underlined in the use of a new expression. Neither Concrete nor The Concrete Society are It is no longer sufficient to crow about responsible for the statements made or the opinions ‘sustainability’; everything from this point James Luckey, Editor expressed in this journal by third parties and Tel: 01276 607158 organisations. onwards is focused on ‘zero carbon’. Fortunately, the cement and concrete [email protected]
www.concrete.org.uk June 2020 concrete 3 WORLD NEWS
NEWS IN BRIEF UK • Helpline Site theft increases Calls to the UK’s Construction Industry Helpline have increased THE CEA (Construction Equipment This also applies to any unusual 25% since early April, reflecting the Association), owner of the plant transport movements for construction rising levels of anxiety and insecurity marking and registration initiative plant, for example, during an unusual within the construction industry. CESAR, says construction plant theft time, or if the vehicle is moving A series of free online lunchtime has increased by an estimated 50% as numerous items of plant belonging Mobile mixing workshops are available for those Covid-19 forced sites to close. Since to different companies. For owners of working in construction; topics range mid-March, there has been a marked construction plant, it may be useful, plant for RCC from mindfulness and meditation to increase in plant and tool theft from for example, to ensure that tracking resilience and controlling stress. Visit site compounds. The sharp spike in companies are alerted to the plants' RAPID International has www.coins-global.com thefts is largely due to construction location.” commissioned a new Rapidmix firms temporarily scaling down work “The coronavirus lockdown 400CW, fully weighed, mobile UK • Covid-19 and shutting jobsites due to the has meant that it’s currently open continuous mixing plant (pugmill) for Four construction specialists are raising pandemic. season for criminal gangs who target Pavement Recycling Systems. The new money for NHS front-line workers. Mick David Smith, chair of Combined construction plant”, said Nick Mayell, Rapidmix is initially being used for George Group, MJS construction, MJS Industries Theft Solutions (CITS), Datatag’s CESAR Police training and the production of roller-compacted Projects and Morgan Sindall Group have said, “As a result of the coronavirus liaison officer and security expert. concrete (RCC) for the Port of Long combined in creating a crowdfunding situation, some construction sites “The abrupt abandonment of work- Beach Middle Harbour Redevelopment page where willing donors can have been forced to close. Under sites has left machinery unsecured and Project in the USA. The Rapidmix will contribute. Mick George Group, on these circumstances, organised vulnerable. Whereas a company would also be involved in the production of behalf of employees, and MJS have criminal gangs may try to exploit the normally wind-down for seasonal RCC and various other materials for each gifted £10,000. The respective situation. Where construction plant closures by off-hiring kit and moving projects across western US states. companies will present NHS workers at and equipment has been left on site, their own machines, sites have closed four specified hospitals with funds for it is hoped that the police will be as overnight, and the thieves are having Seashell concrete thank you activities. Visit: https://bit. vigilant as ever. Any unusual activity, a field day.” LONDON design duo Hyein Choi ly/2Xdn8Pl on or near construction sites which For further information on CITS and Jihee Moon (Newtab-22), have have closed, needs to be investigated. visit: www.theftsolutions.org developed a concrete-like material USA • Rheology made from seashells, in collaboration Progressive Planet Solutions, a with Ventura Projects. Sea Stone is Canadian developer of natural pozzolan Improving concrete New sustainability a lightweight material made from properties, has extended its agreement rheology for 3D printing guidelines for quarries discarded seashells salvaged from the with the University of Alberta to seafood industry, which have been develop an alternative to fly ash for RESEARCHERS from the West THE Global Cement and Concrete ground down and mixed with natural use in the cement industry. The goal of Pomeranian University of Technology Association has published new binders. Newtab-22 developed the the project is to modify the rheology of in Poland have studied methods guidelines aimed at further improving project because shells are largely its zeolite so that it possessed similar of improving the process of the the biodiversity performance of the composed of calcium carbonate, rheology to commercially available rheological properties of concrete. industry’s quarries. Minimising the giving them similar properties to fly ash. So far, the rheology has The study details the application impact of extraction activity is an limestone that is used for cement. been improved with the inclusion of of additive manufacturing technology important priority for the cement and The studio therefore hopes it can be pulverised, recycled glass. The revised in the fabrication of a building wall concrete industry globally. used as a sustainable alternative to proprietary mix design achieved a model, in which the door opening Among the priority areas covered slump that exceeded the target slump concrete. was finished with an automated lintel by the new guidelines are the inclusion of the fly ash-based mix design. installation. of social, economic and environmental Recovery support The objective of the study is to considerations for the future use of UK • Technology CONSTRUCTION minister Nadhim improve the low capacity of 3D the sites once extraction activity Zahawi is looking to bring forward Mott MacDonald has launched printed concretes to transfer loads, ceases, as well as relevant legislative Rehearsive, a new virtual reality infrastructure projects to support which can be particularly troublesome requirements. The guidelines the construction sector’s economic (VR) and desktop product that helps in cases of external components that also advocate the application of users rehearse their construction and recovery, after the Covid-19 crisis. need to be placed on top, such as progressive rehabilitation where He said, “I’m talking to other operational processes ahead of time, precast lintels or floor beams during possible. Stakeholder involvement and unlocking safer, buildable design. It departments to see what projects 3D printing construction processes. consultation is also recommended, allows operators to walk through we can accelerate or bring forward Such an investigation, according to as is ensuring rehabilitation and construction scenarios via VR and because in terms of incentivising the researchers, can prove beneficial in biodiversity plans are in place before desktop, no matter their location. growth, infrastructure is going to be designing larger civil structures using the commencement of extraction important and the Government’s concrete 3D-printing technology. activities at new sites. Czech Republic • fib commitment to infrastructure is going Due to the current Covid-19 outbreak, to be important.” the fib International Conference on DNV GL has approved as qualified, the technology for a full-scale demonstration He also explained that the Concrete Sustainability will now project in Norway to remove carbon emissions at a cement plant. Gassnova, the Government was keeping its options take place on 8–10 September 2021 Norwegian state’s agency for implementation of carbon capture and storage open regarding the fall-out from the in Prague, Czech Republic. Abstract projects, initiated the project which will apply carbon capture technology crisis, such as potential contractual submission is possible until 15 October developed by Aker Solutions at Norcem’s cement plant in Brevik, Norway. Aker disputes. “We will keep under review 2020. Visit: https://bit.ly/2WIwxy0 Solutions’ post-combustion technology is intended to capture and liquefy all interventions to make sure that we
400,000 tonnes per year of the produced CO2 at the Norcem plant. are able to respond in a way that can help businesses.”
4 concrete www.concrete.org.uk June 2020 ffl Elkem Silicon Materials SOCIETY NEWS Members’ library at RECENTLY ADDED The Concrete Society Sarah Gerrard and Edwin Trout continue their monthly delve into The Society’s archives and highlight one of the library’s latest acquisitions.
HIGHLIGHTS FROM THE COLLECTION
Film on concrete Viaduct as well as The Cement & Concrete Association further training (C&CA) was established in 1935 to provide ones” (1971). a central organisation to develop the market The Association Concrete Segmental Bridges: Theory, for concrete as a construction material. It pursued a fulfilled its remit through a range of activities twin approach Design and Construction to AASHTO – advocacy, information, advice, training, of making LRFD specifications research and publishing – and the head office promotional The authors – both based in North America – present their subject as one of the main options in Victoria was supplemented over the years by feature films and for bridge provision today, an approach that offers regional offices, a research station at Wexham technical training speed of completion, minimal traffic disruption, Springs and a residential training centre. films. Of the lower life-cycle costs and an adaptability to From its early days, the C&CA was former, some curved road alignments. But, they argue, the committed to disseminating information, were sponsored by the firms whose work was literature is dominated by treatments of practical through publishing, its library and featured, such as Concrete Islands by McAlpine, construction, so this book on design is one that presentations – either to the public or through while others were made for third parties. fills a gap. And with 1000 pages, it is certainly big its own training courses. Film became a natural Notably, in 1972, the C&CA made City for enough to do so. It opens with an introduction to the different extension of these activities. Film-making the European cement federation, Cembureau, bridge types and typical construction methods, became a parallel to publishing and printing. and this was viewed widely throughout the before describing the usual design loadings and Films, along with photographs, slides and continent. analytical methods. It sets out the theoretical eventually video, were maintained in the Another significant film, on the building of background of the AASHTO LRFD methods C&CA’s library and film became an important the London Bridge, was produced in 1973 and and explains analytical theories for those used medium in presenting concrete to audiences. in 1974 A Heritage To Build On was made to to simply supported bridges and who are less The C&CA was in its prime during the 1960s coincide with the ‘Architectural Heritage’ year, familiar with statically indeterminate structures. and 1970s and these two decades coincided with the aim of promoting a better legacy In the second half of the book, each bridge type is discussed in detail, with simple design examples with the Association’s involvement with film from good concrete structures. presented. Balanced cantilever segmental production. The Annual Report for 1961 had this The films were made to a high standard and bridges, incrementally launched segmental to say of its start, “The Association included some were shown in public cinemas. Several bridges, PT spliced girder bridges, arch bridges the making of 16mm films among its activities deservedly received important awards at film and cable-stayed bridges are considered, along for the first time in 1961. A 40-minute film, festivals. Most of the ‘case study’ films were with substructures. It ends with a relatively brief The Hammersmith Flyover, was completed accompanied by a slim booklet that gave treatment of typical construction methods. in December. This film gives a technical drawings and further details of the projects Combining mathematics and engineering account of the design and construction of featured. mechanics, this substantial volume is aimed at the student and the less-experienced practising this important prestressed concrete structure, At the turn of the decade, film-making was engineer, both for study and to act as a work of and is intended principally for engineers and drawing to a close. The final film, Concrete on-going reference. engineering students. A similar film is being is… was made in 1981 and “provided an CRC Press, 2020, 1028 PAGES made on the construction of the Medway excellent perspective of the nature of concrete Bridge and should be completed by the and showed how attractive it can be in many summer of 1963”. everyday applications and uses”. Once underway, the programme of Film production has long since ceased film-making acquired a momentum: “The and the use of film as an audio-visual aid to film-making continued and three were issued, lecturers has been surpassed by other media, one for farmers, one on concrete paving and but examples of the C&CA’s output remain one on prestressed concrete” (1965); “Three as a collection at The Concrete Society’s films were made for training purposes” (1970); Information Services department – successor Contact The Concrete Society for more details: and “New films included one on the Gateshead to the C&CA’s library. Tel: 01276 607140 or e-mail: [email protected]
6 concrete www.concrete.org.uk June 2020 MASTER ® >>BUILDERS ctilel1ilistri�
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• Single source system approach • Single point liability • Extended life expectancy • Reduced maintenance • BBA Approved Systems BRIDGE CONSTRUCTION AND REPAIR Kilkenny CAS Bridge – connecting a city for the future
Caroline Cavanagh of Banagher Precast Concrete looks at the development of a highly controversial bridge in the historic city of Kilkenny, Ireland.
ilkenny is a growing city and its comprising a five span semi-integral 125m Above: Completed centre depends on good access, bridge crossing the River Nore. Designed by St Francis Bridge. strong permeability and proper Malone O’Regan and constructed by John K urban planning in order for it to Cradock Ltd ( JCL) the St Francis Bridge develop. The Central Access Scheme was was completed in 2016. conceived to encourage and facilitate the redevelopment of the very heart of Kilkenny, Concrete elegance consolidating the city and reducing the It was a requirement that the bridge be simple pressure to develop at the edge of the urban and elegant, with an architectural requisite area, while providing access to develop in a for flat soffits and minimal structural depth sustainable and cost-effective manner over of just 1200mm, due to the major headroom 20 acres (8 hectares) of brownfield city centre restriction. The bridge will support two sites. The Central Access Scheme had been 3.5m-wide carriageways, plus cycleways and the objective of successive Kilkenny city footways, with a design velocity of 30km/hr, development plans since 1980; after lengthy and provide access to the riverbank amenity legal battles it was finally approved in 2009 area. Banagher Precast Concrete collaborated and construction began in 2015. with the consultant, Malone O’Regan, The new access bridge in the heart of on the overall bridge design using their Kilkenny city is positioned in a historic and combined expertise in precast prestressed culturally significant urban location, which is bridgework to develop a solution and create also a Special Area of Conservation, resulting this aesthetically important structure with flat in substantial ecological and environmental soffits and innovative ‘invisible cross-heads’. challenges. Following planning objections, The project began with in-river works the landmark cable-stay bridge originally where JCL constructed six 15m-long bases, proposed was replaced with a simpler yet including two cofferdams in the River Nore, sophisticated structure, which is more visually each with fourteen 900mm-diameter cast- sympathetic to the local surroundings, in-situ bored piles with average depth of
8 concrete www.concrete.org.uk June 2020 Bespoke cross-heads with service portals. Y beam installation.
12m. To add to the project complexity, all Visual impact in-river works had to be completed within The use of concrete was a considered strategy, the restrictive fisheries season. as the visual appearance of the flat soffit of Substantial in-situ reinforced concrete the bridge was of significant architectural works included four piers – each with two importance in the context of the riverbank cylindrical columns, averaging 8m high and amenity parks routed below the bridge on 1200mm diameter – and two abutments, the north and south banks. The concrete each 15m wide, and a total concrete volume finishes to the precast elements and overall of 2400m³. aesthetics were critical to this project in light While work commenced on-site, the of the stringent planning conditions and the unique ‘invisible cross-head’ moulds were low headspace above the walkway running designed and manufactured to incorporate alongside the river. By manufacturing the the service portals, the 70 prestressed Y beams off-site in a controlled factory setting, beams were poured and the other major it ensured quality and uniformity in the precast element – 1800m² of precast concrete concrete finish. permanent formwork for the bridge deck – To complement the aesthetic, cantilevered was manufactured. structural steel walkways were incorporated With a tight one-week window for precast on either side of the bridge for cyclists and installation, the execution of multiple crane pedestrians, along with a unique curved and set-ups, deliveries via restricted routes and cantilevered viewing platform. installation had to be planned in great detail The design also specified the provision and executed with exact precision. of local Kilkenny limestone cladding to First, the technically challenging bespoke abutments, bespoke bronze alloy handrails, cross-heads were delivered, installed and exposed aggregate containment barriers stitched in-situ. Then during the course of and innovative low-level lighting to subtly the week, 70 prestressed Y beams measuring enhance the aesthetics of the structure. up to 26m were delivered to site just-in- time and installed in sequence to mirror the different crane set-ups, followed by the installation of the services and the precast deck. A major advantage of using prestressed Y beams was that they could be lifted into position safely and quickly, meaning they were immediately stable and provided a safe, solid deck from which to work. This was very important, as the safety of construction operatives is always a paramount consideration and was especially relevant here when the team was working over water and so many services had to be incorporated into the structure deck and cross-heads. Completed structure – invisible cross-heads and flat soffit.
www.concrete.org.uk June 2020 concrete 9 Completed structure – restrictive headspace.
Sustainability A key aim for Kilkenny County Council was that the bridge should have a positive impact on helping achieve its goals for sustainable development and environmental improvement. With the opening of the bridge, the perennial congestion has been alleviated with a consequent reduction in local carbon emissions. The provision of a dedicated and safe foot/cycle way has also encouraged non-motorised transport modes. At the design stage, careful consideration Completed bridge showing walkway. was given to ensure that the risks of adverse environmental effects such as scouring were not increased and works were undertaken within the required fisheries season. The design consultant and precast engineer designed and created an elegant flat soffit structure, using innovative ‘invisible cross- heads’ and steel plates cast into the ends of the beams. This bridge is an integrated structure, with a limited number of movement joints minimising whole-life costs. The use of prestressed Y beams also delivered structural advantages over other beam types, which lead to significant construction savings and reduced work on-site. The concrete structure as it stands today is robust and provides lasting transport resilience. Concrete was the natural choice, ensuring that this transport link can Aerial view of completed bridge. withstand environmental effects and climate change with minimal maintenance. Winner of the 2016 Excellence in Civil Engineering Award (£4.5m–9m) by the Civil Engineering Contractors Association, Kilkenny Central Access Scheme Bridge Owner Kilkenny County Council the new St Francis Bridge facilitates the Consulting engineer Malone O’Regan Consulting Engineers sustainable development of Kilkenny city Contractor John Cradock Ltd (JCL) centre and in so doing maintains commercial, Design consultancy/ Banagher Precast Concrete economic, social and cultural vitality in the material supplier historic core of the city.
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The most common concrete deterioration processes in bridges One of the reasons why concrete is the most common construction material is its outstanding durability properties, especially in a harsh environment such as marine. Performance of concrete elements in bridges (ie, decks, beams, substructures, etc) depends on various factors, including how they have been designed, constructed, preserved and protected during their service life, and to what types of environment they are exposed. Kaveh Afshinnia of TY Lin International reports.
ypically, concrete elements such of reinforced concrete (ie, near supports in as concrete decks, pier caps, piers concrete beams). and beams near joints that are Non-structural cracks are caused by T exposed to weather, moisture and thermal expansions and contractions, aggressive chemicals are more susceptible shrinkage of concrete, freeze–thaw cycles, to degradation. The most common corrosion of reinforcing bars, alkali–silica manifestations of concrete deterioration are reaction (ASR), sulfate attack, etc. cracks, spalls, delamination and efflorescence. Delamination and spalling Cracks Corrosion is the main cause of delamination Structural deficiencies are one of the causes of concrete decks and piers, especially in of concrete cracks, which are mostly due to bridge decks. Typically, sounding is the improper design and detailing of concrete most common way to detect delamination in structures. Structural cracks caused by such concrete surfaces. Chain drag and hammer deficiencies are usually encountered in sounding can be used to detect delamination highly stressed areas where demand stresses of concrete in horizontal and vertical/ are greater than the resistance of reinforced overhead surfaces, respectively. concrete. Visual inspection is the best method to Locations and orientations of structural detect spalling of concrete. However, the area cracks can help engineers to discover the type that needs to be repaired is, very often, greater of deficiencies. For instance, flexural cracks than the spalled areas since delamination of on beam sides are vertical where concrete is concrete can be encountered at the perimeter in tension (ie, near mid-span and below the of the spalled location. beam in simply supported concrete beams), As described above, the most common while shear cracks are diagonal where shear cause of concrete cracking, delamination and loads are greater than the shear capacity spalling is corrosion of embedded reinforcing
12 concrete www.concrete.org.uk June 2020 Figure 3: Corrosion of reinforcing bars. Figure 4: Efflorescence on the surface of a traffic barrier. Note Note rust beneath the epoxy coating and delamination of the concrete on top face of the barrier. damages and debonding of epoxy coating. bars. Steel reinforcement is embedded in Once the chloride content in the vicinity concrete to compensate concrete’s lack of a reinforcing bar exceeds threshold, the of tensile strength. Due to the presence passivation film is damaged and can no of hydroxide ions and calcium hydroxide, longer protect the steel. Steel then becomes the pH of concrete material is typically susceptible to corrosion and corrosion approximately 12–14. In such high alkaline products (which occupy more space than environment, steel can guard itself by creating steel by itself ) accumulate on the surface of a layer (passivation) by which it is shielded the steel, apply pressure on the surrounding against corrosion until the protection layer is concrete and cause cracks, delamination and undamaged. spalling. During winter, de-icers that contain Figure 1 shows cracks, spalls and chlorides penetrate concrete decks and delamination on the surface of the concrete, reach the layer of steel reinforcement. as well as exposed corroded reinforcement. BRIDGE CONSTRUCTION AND REPAIR
Figure 5: Clogged deck drain. Figure 6: Deterioration of repaired concrete.
Figure 2 shows corrosion of reinforcement and protect superstructure and substructure at the bottom surface of a concrete deck near below the joint, while for close joints (ie, existing drainage. Causes of this distress pour seals, compression seals, strip seals, etc), might be due to the penetration of de-icers the design team needs to ensure run-off into the concrete deck along with a poor water and aggressive chemicals do not pass drainage system (drainage might be clogged, through the joints and cause deterioration or concrete deck was not cambered properly of substructure. Drainage systems need to be to discharge run-off water). regularly inspected and maintained to ensure they work properly. Figure 5 shows a clogged Efflorescence bridge deck drain. Once soft water from rain or snow penetrates concrete (ie, concrete decks, retaining walls, Failed previous repairs traffic barriers, pier caps, etc), it dissolves Three key items that need to be considered calcium hydroxide which is one of the for having proper and durable concrete products of Portland cement hydration and repairs are the identification of the leaches away from the exterior face of the actual cause of deterioration, selection of concrete (ie, bottom side of bridge decks or appropriate repair materials and preparation exterior face of concrete retaining walls). of substrate surfaces. This leachate then reacts with CO2 and Causes of concrete deterioration in bridges produces calcium carbonate which remains might be due to corrosion of reinforcement, on the surface of the concrete –‘efflorescence’. freeze–thaw, sulfate attack, ASR, shrinkage, Efflorescence causes both aesthetic and structural deficiencies, improper design and strength issues. Dissolution of calcium- detailing of structure, etc. Selection of the containing materials negatively affects the appropriate repair material is essential for strength of the concrete. Figure 4 shows durable and long-lasting repairs and it varies efflorescence on the surface of a traffic barrier. based on the application and exposure. The most common chemical additives that are Joints and drainage issues added to the repair materials to enhance Expansion joints are often specified to their durability properties are corrosion accommodate superstructure movement due inhibitors, shrinkage-reducing admixtures, to temperature changes and/or applied live and polymer modifiers. To accommodate loads. Without expansion joints, contraction similar movement, the thermal expansion and expansion of the bridge are restrained, coefficients of both repair and substrate which results in deterioration of the concrete materials need to be in the same range to deck. avoid development of high stresses at the Typically, two types of expansion joints interface of the repaired area. The surface are specified for bridge decks: open and close of the substrate needs to be prepared to joints. For open joints (ie, finger joints, butt increase bonding between repair concrete and joints, sliding plate joints), drainage systems substrate. Figure 6 shows a failed repair on need to be placed to discharge run-off water the surface of a bridge deck.
14 concrete www.concrete.org.uk June 2020 adapt verb to change your ideas or behaviour to make them suitable for a new situation
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Visit: www.peri.ltd.uk or to find out more about our 4-step customer support plan. www.peri.ltd.uk Concrete Bridge Development Group Technical Guide No 16 – Temporary Works for Concrete Bridges Temporary works are used throughout the construction process of concrete bridges. Comprehensive guidance on their design, installation and use is generally available but is found in many different and unrelated references. Consistent with its mandate to promote excellence in the design, construction and management of concrete bridges the Concrete Bridge Development Group has recently published Technical Guide No 16 – Temporary Works for Concrete Bridges(1) (TG16). Jeremy Barnes and Nigel Hewson of Hewson Consulting Engineers report.
G16 provides a review of the range to the construction engineering process Above left: Proprietary of temporary works used in the and, ultimately, the temporary works tower system. construction of concrete bridges. design is outlined. The importance of an T It provides a consolidated source initial construction sequence referencing of guidance on these temporary works and assumptions made in the design is supplements, with further references for highlighted and how these can be used by more detailed information. The guide aims contractors and their design teams to produce to supplement available guidance where cost-effective solutions. appropriate and is targeted at both temporary Included within TG16 is a review of and permanent works designers, clients and current temporary works design guidance contractors. The range of temporary works and an overview of the temporary works used for concrete bridges both in the UK and approvals process for the UK’s major client overseas is described. organisations. The current guidance on While TG16 recognises that all projects the transition to Eurocodes for temporary are unique, it aims to provide clarity of works design is reviewed, including the relationship between permanent the incorporation of proprietary items. and temporary works designers within Proprietary items are regularly used in the overall construction engineering temporary works for concrete bridges and process. It describes how decisions over are often designed on a different basis to the the construction methodology can have a limit state Eurocodes. The inherent danger significant impact on the final state of stress in mixing design approaches is detailed and within a concrete bridge and therefore the reference to further advice provided. permanent works design. The flow from A section is provided in TG16 that reviews construction methodology assumptions temporary works that are commonly used
16 concrete www.concrete.org.uk June 2020 BRIDGE CONSTRUCTION AND REPAIR
in concrete bridge construction. Details of this methodology on the design of the are provided within the guide where permanent works are also discussed, alongside the use of these items would impact the the key temporary works systems required. permanent works. Drawing on both UK Similarly, the particular complexities and international practice, the range of such associated with construction of concrete temporary works is detailed. cable-stayed bridges is contained in a A chapter in the guide is dedicated to the temporary works used in the construction While TG16 recognises that all projects of the substructures for concrete bridges, “ including foundations, piers and abutments. are unique, it aims to provide clarity of Despite the range of construction techniques the relationship between permanent and for concrete bridges, there is a commonality temporary works designers within the in substructure construction that is described in the guide. Both in-situ and precast overall construction engineering process. construction are outlined and for piers ” both single- and multi-lift construction dedicated chapter. It was recognised that are considered. The specialist techniques much of the temporary works used are associated with the multi-lift construction already described in earlier sections of the for the significant pier and towers associated guide and therefore the chapter concentrates with major bridge crossings are also on their applicability to cable-stayed bridges. described. The guide concludes with an overview of offline construction and the different Construction techniques techniques associated with the installation of The range of superstructure construction preconstructed bridges. It is recognised that techniques for concrete bridges are covered the associated temporary works are specialist in separate chapters. In-situ, precast beam- and anything more than an overview is and-slab, and concrete box girder decks are beyond the scope of the guide. In keeping described, including the different methods with the theme of the guide, the implications for their construction. In keeping with on permanent works using these techniques the theme of the guide, the effect on the are outlined. permanent works for the same deck form Reference: but constructed with different techniques is 1. CONCRETE BRIDGE DEVELOPMENT GROUP, Technical explained. Guide No 16. Temporary Works for Concrete Bridges. Due to its particular complexities, a The Concrete Society, Camberley, 2020. chapter is dedicated to the temporary works associated with incremental launching. Technical Guide No 16 and other CBDG While it is recognised that this technique and Concrete Society publications are is predominantly used with concrete box available from the Concrete Bookshop. girders, it was felt that the particular aspects Visit: www.concretebookshop.com. of this construction methodology warranted a separate chapter. Again, the implications
Precast shell temporary works. Form traveller.
www.concrete.org.uk June 2020 concrete 17 Working around buildability challenges to deliver a concrete bridge Ilyass Meslek of CCL looks at the structural design and use of bearings for a bridge on the Congleton link road project in Cheshire.
ike many semi-rural small towns Challenging topography Above left: The within commuting distance of The River Dane crossing is a two-span bridge River Dane crossing large cities, the Cheshire town of composite construction, with reinforced comprises two L of Congleton has seen its narrow concrete abutments on the west and east composite steel streets overwhelmed by traffic over the banks of the river and a single concrete spans installed onto past few years. The congestion issues have pier on the east bank, all constructed with concrete abutments become a cause of frustration for residents 1200mm piles. The abutments and pier and a concrete pier. and commuters alike, leading Cheshire East were all cast in-situ, beginning with the pier, Council to propose a 5.5km link road to prior to assembly of the deck. The spans are Above: The steelwork create a bypass that will free the town centre composed of steel girders, installed first from for the bridge’s spans of through-traffic. The plan aims to reduce the east abutment, then from the west and was lowered onto the the number of vehicles on Congleton’s roads tied together before a carefully sequenced bearings, engineered and boost the local economy as a result, by concrete pour, aligned to the optimum by CCL. making the town more accessible to visitors. loading conditions for the steelwork, to create The £90 million Congleton link road the bridge deck. will join the A534 Sandbach Road (to The spans are of unequal length, with the west of Congleton) with the A536 a 62m span crossing the water and a 25m Macclesfield Road (to the north of the span completing the path of the bridge town). Construction and civil engineering from the pier located on the east bank to contractor GRAHAM is responsible for the eastern abutment. There is a very high delivering the five-phase project, which embankment on the western side of the river includes two bridges: one to enable the and, although the Graham team cut into this diverted traffic to cross the River Dane and high embankment to construct the western another over a local B road, Giantswood abutment, there is a vertical difference of 20m Lane. The company worked with CCL, between the west and east sides of the river, the specialist in engineered solutions for which has resulted in the 62m span being structures, on the bridge elements of the constructed at a 1/20 gradient. The bridge scheme, with CCL providing a variety of has been designed to provide a floodplain, bridge bearings to meet the requirements allowing for worst-case scenario flood of the bridge design and challenging planning, because the River Dane experiences topography. flash flooding during periods of heavy rainfall.
18 concrete www.concrete.org.uk June 2020 BRIDGE CONSTRUCTION AND REPAIR
The original proposal for the bridge the structure and in absorbing the vertical included an additional pier on the west bank load of both the span and the vehicles that of the river to support the larger span, but the will use the crossing. challenges of the topography and the water At the western abutment, where the table prompted a redesign. The steep bank span is designed to slope from the high that descends from the western abutment to embankment down towards the pier and the location earmarked for the western pier the lower embankment on the other side, created issues with accessibility. Erosion of five free-sliding spherical bearings were the riverbank was a further consideration. To installed to allow 2293kN of vertical load and overcome the buildability issues created by movement in all directions. These bearings this topography, which were likely to include were designed with a preset angle of 0.8° on accessing the site for the proposed western the top plate to allow for the gradient of the pier from the east bank, the bridge design was span above and enable horizontal movement altered to the single pier on the east bank. and rotation in all directions. Alongside these This decision reduced the temporary works free-sliding bearings, a single guided spherical involved, aided the build programme and bearing was also installed on the western helped to manage the level of risk, thereby abutment, capable of absorbing both 2251kN benefitting the project. of vertical load and 462kN of horizontal load, while allowing movement in one direction Load and movement only. This bearing was also designed with CCL designed and manufactured the a preset angle of 0.8°, aligned to the angle bridge bearings to meet the loads and of the span. It also allows articulation of the forces stipulated by the project’s structural bridge in response to seasonal longitudinal engineers, and the change in the design contraction and expansion of the steelwork strategy altered the requirements for the by as much as 100mm, while preventing any bearings. perpendicular movement that could damage The revised single-pier design uses the bridge structure. the weight in the substructure of the east For the pier, CCL designed and supplied abutment to support the span, so the deck five free-sliding pot bearings, which will take was redesigned to take the moment, which 5816kN in vertical load and allow movement is greatest over the pier on the east bank, and in all directions. One guided pot bearing, transfer it through the east abutment and into capable of taking both 5733kN of vertical the foundations. The span was temporarily load and 886kN horizontal load, was also Below: Following installation of the restrained at the eastern abutment during installed here and this has been designed to steelwork for the spans, a carefully construction, before being cast permanently allow movement in a single direction. sequenced concrete pour took place. into the diaphragm, removing the need for (Photo: 360photosurvey.com 2020.) any bearings in this location. Counting down to completion Bottom: Construction of the River Dane Although the deck is fixed at the eastern Initially planned for completion before the abutment to transfer the load from the end of 2020, the Congleton bypass was on crossing is nearing completion, with the span through the concrete structure and schedule to complete on time, with both wider scheme ongoing for the remainder foundations, this does not affect the bridge elements completed. Like many of 2020. (Photo: 360photosurvey.com 2020.) rotational and longitudinal movement projects, the completion timeline may be enabled by the bearings installed at the affected by the working restrictions resulting western abutment and the pier. In these from Covid-19 but, once open to traffic, the locations, along with a movement joint at new bypass will ease congestion and improve the western abutment, the bearings play an the daily routines of Congleton residents for essential role in allowing movement through years to come.
From the high embankment on the western side of the river to the east side there is a vertical difference of 20m. Concrete field testing technician: ACI–ICT certification programme rolled out
The Institute of Concrete Technology, in partnership with the American Concrete Institute whose long- established certification scheme is enshrined in best practice wherever ASTMs apply, offers a scheme tailored specifically to EN Standards. It aims to assess and validate the skills of technicians in performing specified tests on fresh concrete. Edwin Trout and Raman Mangabhai look at the scheme’s roll-out.
wo-day sessions include a copy of concrete construction. All six candidates were Above: The latest the workbook, revision exercises successful in gaining certification and several session – in Riga, and practice on testing equipment, have since been appointed as examiners to the Latvia. T multiple-choice examination and scheme. practical assessment by ACI–ICT appointed The first session publicly promoted to examiners. Successful candidates are awarded industry – rather than prospective examiners a certificate and a card valid for five years. – was held in Whitminster, Gloucestershire, The scheme is co-sponsored and jointly on 17–18 September and was kindly badged as ACI–ICT to ensure the global hosted by the Cullimore Group. It was fully recognition of certified technicians to an agreed benchmark. The months since the ACI–ICT scheme for certifying concrete field testing technicians (CFTT) to EN Standards was launched last year have seen a rapid roll- out of the programme and demonstrated a considerable degree of demand. The first session to follow the April launch was held on 14–15 June 2019 in Belfast. It was a preliminary session with the aim of participants becoming examiners to help extend the CFTT programme in Northern Ireland. The session was applauded for its comprehensive reinforcement of correct practice in the testing procedures so critical to An example of the site card.
20 concrete www.concrete.org.uk June 2020 Prospective examiners in Belfast.
subscribed with ten candidates and there was a waiting list for cancellations. Candidates came from a variety of test houses and independent ready-mixed concrete suppliers, along with Aggregate Industries and Breedon Group. There was even one who came especially from Latvia. On the day, and setting the pattern for the following sessions, the two examiners led the cohort through the requirements of the Standards and in the early afternoon undertook a practical demonstration of the seven procedures by way of demonstration. Finally, the candidates sat a surprisingly exacting multiple-choice examination of 64 questions. On day two, each candidate took a turn to attempt a satisfactory performance of the seven sampling and testing methods covered. Of the nine attending, seven passed and have now been certified with an ACI– ICT co-branded certificate and site card, each valid for five years. On 28–29 October 2019, a second session was held further north, in the Warrington laboratory of GCP Applied Technologies, with GCP’s Antony Hegarty joining the team of examiners. Then on 5–6 November, a further seven attended a follow-on session at Whitminster, including one long-distance candidate from Australia. Review An end-of-year review saw the ICT’s workbook updated to reflect the latest amendment of the Standards (EN 12350(1) and EN 12390(2)) and the written examination extended to 90 minutes and adjusted to weight the marking between sections more equitably. There are now 70 questions rather than 64, with an equal number of questions for each of the seven Standards included. In addition, branded banner stands were purchased and the scheme publicised with an article in Concrete International(3). The programme entered 2020 with a flurry of activity. Much the same as was arranged in Belfast last June, five prospective
www.concrete.org.uk June 2020 TRAINING AND EDUCATION
ACI–ICT EN Standards CFTT sessions. Mattest laboratory equipment, Dublin.
ICT assessors were themselves examined at Table 1 – Certification in numbers a session arranged with the Irish Concrete Date Candidates Resits Passes Society and kindly hosted by Mattest in 2018 44 0 16 Dublin on 20–21 January. Back in England, the next session was held at Sika’s premises 2019 56 42 54 in Welwyn Garden City early in February. 2020 41 2 38 Ten candidates attended from a range of Total 141 44 108 companies based in the south-east, along with two others resitting the written exam. Pass rate 77% Following the success of the initial Note: The pass mark is 70% overall, with at least Belfast session, the ACI–ICT certification 60% required for each of the seven sections and a programme is now being made more widely pass in both the practical and written exams. available to the sector in Northern Ireland. The scheme there is being conducted with the financial support of the Construction Industry Training Board NI and the too. It’s a demanding process, with some involvement of The Concrete Society candidates undertaking two attempts to Northern Ireland Region, with Bryan Magee achieve certification, but the figures indicate the local co-ordinator. The first ‘open’ session a very pleasing uptake by industry and was held in Crumlin at the end of February, achievement by individuals. with candidates attending from both sides With expressions of interest from half a of the border. It was oversubscribed and a dozen more companies, the CFTT steering reserve list is now in place for the next session. committee is now actively planning sessions Early March saw the ICT examiners travel for the summer and autumn in both England to Riga for the first session in Latvia – just and Northern Ireland, while making before Covid-19 restrictions were introduced provision for additional sessions in the – where the candidates went on to achieve an Republic of Ireland and the Baltic states. exemplary pass rate of 100%. Two companies, moreover, have approached the ICT for in-house sessions for Positive their own staff, at locations in Scotland and The reception by industry has been northern England. overwhelmingly positive, with the major Further information: integrated materials companies represented A future session will take place at Mapei’s premises in among the candidates and feedback such Halesowen on 19–20 October. Visit: www.theict.org for more details. as: “I am very pleased; the course was really well run and as a newcomer to the industry References: was informative yet enjoyable”; “The study 1. BRITISH STANDARDS INSTITUTION, BS EN 12350. booklet covered everything, as you’d expect… Testing fresh concrete. BSI, London, multiple parts. 2. BRITISH STANDARDS INSTITUTION, BS EN 12390. the revision session was very good and the Testing hardened concrete. BSI, London, multiple parts. practical demonstration was very helpful”; 3. LEWIS, R.C. and TROUT, E.A.R. ACI and ICT Collaborate and “the examiners were exemplary”. on Certification Program. Concrete International, And the results have been very satisfactory Vol.42, No.2, February 2020, pp.27–29.
22 concrete www.concrete.org.uk June 2020 FREE online webinar Guide to Waterproofing
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For further information on our webinars or product range contact: Fosroc International Limited Tel: 01827 262222 Email: [email protected] Students from University of Cambridge on their Noelia Lawson, student from University of completed Ravenspurn Oil Platform, 2019. Leeds, attended with JN Bentley in 2019 to build the Kingsgate Bridge.
Looking to a zero-carbon future with Constructionarium
Constructionarium is a not-for-profit organisation providing experiential learning to students studying built environment courses and professionals seeking a practical understanding of the construction process. Charlotte Ainsworth reports on the transformation underway to deliver the latest training in sustainable technologies.
onstructionarium designed a including their graduates and apprentices, bespoke 6-hectare site at Bircham spot emerging talent and invest in the next Newton, Norfolk, within the generation of construction professionals. grounds of the CITB’s National C Move to zero-carbon industry Construction College in 2004. Since then, over 13,000 students, graduates and As one of the world’s most carbon-intensive professionals have completed one of the industries, construction has a powerful 14 experiential learning projects, which obligation to reduce its own impact and are based on iconic structures from around under the leadership of chair Keith Clarke the world, including the Gherkin and the (former CEO of Atkins) and chief executive Millau Viaduct. Once on-site, delegates Julia Stevens, Constructionarium intends to must form multi-disciplinary teams and act contribute to the decarbonisation agenda. as the ‘contractor’, reporting to their client Realising that the transition to net zero on a daily basis. Supported by industry carbon would require a transformation in partners, they decide on their own project current training provision, in order to deliver plan and team structure, and must deal with the professional and technical skills required, unexpected situations (nesting birds or a the company began to plan for a second site, shortage of bolts) and weather conditions as with the aim that this would be the UK’s first they arise. zero-carbon training facility. Collaboration with industry is key In 2019, planning permission was granted and Constructionarium has facilitated for the new site to be located within the longstanding partnerships between Berkeley Homes Southall Waterside contractors and academic institutions, which regeneration area in Greater London, have benefitted both parties over the years. which was on track to open in March 2020 Students gain commercial awareness with before the Covid-19 pandemic hit. The access to experienced professionals, while portfolio of activities that Constructionarium firms are able to develop their own staff, offers has been updated, ensuring that
24 concrete www.concrete.org.uk June 2020 Students from University of Westminster undertaking a concrete pour.
Aerial view of the Constructionarium site at Bircham Newton. (Photo: Leica Geosystems.)
projects themselves are carbon neutral and carbon, groundworks, surveying, manual embedding a focus throughout on sustainable handling, mental health first aid and site construction methods. management skills has been developed and New projects are in the pipeline, such Constructionarium is now a CITB-approved as the ‘Façades: design for delivery’ course training organisation, which opens up its developed in partnership with Berkeley courses to levy-paying companies. Homes. Existing projects have been digitalised or redesigned, including the NetZeroHub learning platform Gherkin, which has been ‘decarbonised’ by In centring its offering around sustainability, The newly ‘decarbonised’ Gherkin, designed Caunton Engineering who designed a new Constructionarium found that both industry by Caunton Engineering and constructed steel frame that can be erected off a ground awareness and individuals’ knowledge of by its apprentices, 2020. beam. A range of short courses covering low the science behind climate change were low. TRAINING AND EDUCATION
Climate science is often confusing, with contradictory claims, muddled debate and media sensationalism, so it is unsurprising that levels of understanding around key concepts can be low. In order to achieve such ambitious targets at an accelerated rate it will be vital to inform, educate and engage the whole workforce, as behaviours and mindsets will not change unless individuals understand why changes are necessary. To this end, Constructionarium has developed the concept of the NetZeroHub – an interactive learning platform that will be explicitly targeted at those working in the built environment sector. The aim is to enable a golden thread of knowledge on climate change that can be delivered across all organisations, departments, functions, disciplines and levels, Angela Ruskin University students from site managers to CEOs. constructing the Gherkin in 2018. ...in order to deliver the professional and“ technical skills required, the company began to plan for a second site, with the aim that this would be the UK’s first zero- carbon training facility.” Information about today’s solutions and tomorrow’s innovations will be clear, easy to understand and a mixture of original material alongside selected resources and presented in different formats so learners can find their own path at their own pace. The NetZeroHub concept focuses on bite-sized iterative learning, where the user can build a personalised journey through the diverse complexities of climate change. Learning will Students from University of Westminster be delivered in a variety of CPD-accredited constructing formwork. formats, including podcast and video, and ‘currently trending’ topics allow users to keep abreast of the latest research and analysis. Constructionarium presented the NetZeroHub concept at Futurebuild in February 2020 and received a positive response from a number of companies who have declared net-zero policies but have no foundation of learning with which to engage their own workforce or supply chain. Opportunity for change The Covid-19 pandemic has represented a global crisis for the construction industry, but in searching for a silver lining to the cloud it has also offered a rare opportunity for organisations to engage with their workforce and across supply chains. The response to the crisis should be an investment in the future and a push towards zero-carbon construction will both stimulate economic activity and achieve environmental goals. Students in PPE, stocks of which were donated to Queen Elizabeth Hospital in March 2020.
26 concrete www.concrete.org.uk June 2020 Archived concrete
The Concrete Society holds an extensive on-line archive of articles from concrete magazine. This collection, stretching right back to 1968, is available free to all Society members*. Articles can either be downloaded in web-ready PDF format or e-mailed to you by request. If you are a member but have not registered to use the website or have forgotten your log-in details please e-mail: [email protected]
* A charge of £10 per article is made to non-members
For all your CBDG publications VISIT
concretebookshop.com Technical presentation – AECOM. Practical training.
The benefits and evolution of training Mike Threadgold of Fosroc and chair of the Structural Concrete Alliance training committee explores training and the changes made to training development in recent years.
raining is not just important to Training and learning present a prime • can improve well being people and companies, it is also vital opportunity to expand the knowledge • increased innovation in strategies and to be able to allow both to develop base of all employees, from both a personal • products T their full potential and should perspective and that of the company. In • can improve health and safety be a fundamental part of any company’s the current climate, many employers find reduced faults, waste or customer development programme. development opportunities expensive and complaints with competent work force. Over the years, the philosophy behind employees attending training sessions also training has not changed and the quotations miss out on work time, which may delay Improved employee performance below are as true today as they always were: the completion of projects. These potential The employee who receives the necessary • Albert Einstein said, “Intellectual growth drawbacks can be managed with a balanced training is more able to perform well in their should commence at birth and cease only approach to training, using both old and job. The training will give the employee a at death.” new techniques. Training and development greater understanding of their responsibilities • Benjamin Franklin said, “Tell me and I provide both the individual and organisations within their role and in turn build their forget; teach me and I may remember; as a whole with benefits that make the confidence. This confidence will enhance involve me and I learn.” cost and time a worthwhile investment. their overall performance and this can only • Mark Twain said, “Anyone who stops The return on investment from training benefit the company. Employees who are learning is old whether 20 or 80. Anyone and development of employees is really a competent and on top of changing industry who keeps learning stays young.” no-brainer. standards can help a company hold a position So what are some of the benefits? as a leader and strong competitor within the However, what has changed is how training • improved employee satisfaction and industry. and personal development are delivered and morale The investment in training that a company many industry companies have put this to the • improved employee knowledge and makes shows employees that they are valued forefront of their development programme. opportunity and helps create a supportive workplace. They are regularly reviewing the process and • retention of employees long term Employees may gain access to training they training provided to not only employees but • personal development of employees would not have otherwise known about or also customers and the wider industry. • help attract top talent if the business is sought out themselves. Employees who feel In the process, companies need to seen as one that values and invests in appreciated and challenged through training understand what does training and workers opportunities may feel more satisfaction development mean to their organisation and • help the business adapt to change and toward their jobs and develop new skills and their employees? prepare for growth job opportunities.
28 concrete www.concrete.org.uk June 2020 TRAINING AND EDUCATION
Most employees will have some weaknesses in their workplace skills and a training programme allows those skills to be strengthened. A development programme brings all employees to a higher level so they all have similar skills and knowledge. This helps reduce any weak links within the company or individuals relying heavily on the skills of others to complete basic work tasks. Providing the necessary training creates a good overall level of knowledge, with employees who can take over for one another as needed, work in teams or work independently without constant help and supervision from others. A skilled and trained workforce also makes for an improvement in social skills and for a happy workforce, which in turn provides an overall better social environment in the work place and at home. A robust training and development programme ensures that employees have a consistent experience and background knowledge. The consistency is particularly relevant for the company’s basic policies and procedures. All employees need to be aware of the expectations and procedures within the company, and these increased efficiencies in processes will result in financial gain for the company. There also needs to be a regular review of training and policies and upskilling to take on board changes in the workplace and qualifications. Productivity Productivity usually increases when a company implements training courses. Increased efficiency in processes will ensure The Concrete Society maintains a world- project success, which in turn will improve the company turnover and potential leading library specialising in concrete and market share, and allow it to develop new offers a range of services to help you locate the opportunities. information you need. Bang up to date! The latest journals added daily
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40% discount on services to members Enquiries / Literature searching / Library visits / Desk research / Document delivery / Loans / Current awareness / Standards alert / Daily news JF Hunt online webinar. For details of The Society’s extensive collection and of its research and updating services, Tel: 01276 607140 or e-mail: [email protected] www.concrete.org.uk June 2020 29 TRAINING AND EDUCATION
Reduced employee turnover presenter, bigger numbers are able to attend and an NVQ centre for the registration of Colleagues are more likely to feel valued and the whole theme of the presentation qualifications. if they are invested in and, therefore, less can be tailored to those attending. Likewise, “In addition, NSAC supports federations, likely to change employers. Training and for the attendee there is no embarrassment trade associations and employers to organise development are seen as an additional in raising a hand in front of peers or and develop training programmes, train company benefits. Therefore, not only do management to ask a question while they are assessors and support the development of recruitment costs reduce but also the costs of also able to repeat the presentation on certain qualifications specific to their needs.” constantly changing workforce due to staff e-learning platforms too. Colin Seabrook, group curriculum director retention. That said, while technology provides an for construction and technical services at A strong and successful training strategy alternative way to present, it should not be New City College (NCC), says, “This is a helps to enhance a company’s reputation used as the only solution and purely another busy time for construction across London and profile, develop a brand and make a ‘string to the bow’. There should always be and the south-east, and a busy time for the company a prime consideration for graduates a place for face-to-face training and bespoke specialist concrete sector. NCC is developing and mid-career changes. This has been one-to-one assistance. Our industry thrives a Concrete Centre of Excellence working supported by an investigation undertaken by on these principles and therefore should with trade associations in the industry. graduates at Cambridge University, which always promote them. “New City College holds the Quality showed graduates were more inclined to Tim Mole, Fosroc’s general sales manager Kitemark of Mayor’s Construction Academy, join a company with a clear training and UK and Ireland, says, “Throughout Fosroc, giving access to funding and support development strategy. training our employees is taken very seriously, from the Mayor of London’s Office. With Training can be of any concept that is from company induction process through to numerous sites across east London, and north relevant to the work or responsibilities of the job-related training and bespoke employee and west Essex, NCC is well placed both individual, and can be delivered by a selection requirements. We also carry our philosophy in geographically and in terms of known quality of processes which may include: training through our network of distributors, to cater for the training needs of the industry. • courses by trade bodies such as The specifiers of our materials and those “To demonstrate its support, NCC has Concrete Society, Structural Concrete operatives that would apply our materials. set aside a location within the Epping Forest Alliance, etc “This is clearly the approach Fosroc Campus for Structural Concrete Alliance • on-the-job learning has taken internationally with training training and delivery, including a designated • mentoring schemes sessions developed internally, using National classroom and outside training space. • in-house training Occupational Standards and working with Alongside this will be additional space for the • online learning the various industries we operate within, to Concrete Drilling and Sawing Association, • webinars develop new training and review and amend two very distinct but linked sectors. As the • college courses existing courses to meet industry needs.” provision grows and with new building • manufacturers’ courses Lee Smith from the National Specialist works taking place over the next few years at • qualifications both educationally based Accredited Centre (NSAC) says, “The the Rainham, Tower Hamlets (Poplar) and and via the Qualifications and Credit NSAC was created by CITB in 2003 to Hackney campuses, New City College is well Framework. support the specialist vocational areas within placed to add additional space for training the construction industry, such as specialist projects as the need arises.” Traditional training methods within the concrete applications. The specialist sector The committee of the cross industry- construction industry are evolving and the frequently has limited access to qualifications training group, along with CITB, has influx of technology should be harnessed for their workforce. been reviewing the qualification within rather than ignored. The arrival of webinars “NSAC partners with trade bodies and the specialist concrete occupations suite of and ‘virtual’ seminars offers huge benefits employers to provide a quality assurance qualifications. This has not only seen the for both presenter and attendee. For the service, information advice and guidance, updating of existing qualifications but also the introduction of new ones identified by the industry and these include install composite Seminar day – Structural Concrete Alliance. strengthening system, install corrosion prevention system, survey and testing concrete structures as well as combining the spray application qualifications. Following funding from CITB, we are now and working with the NSAC to introduce these qualifications and train assessors. Deiniol Williams, President of The Concrete Society, says, “The Society is fully supportive of training and education within our industry, ranging from collaboration with the University of Derby to links with the ICT qualifications for technicians and training provided in-house by our technical officers. Training ensures we have a capable and competent workforce for the future.”
www.concrete.org.uk June 2020 DURABILITY/AGGRESSIVE ENVIRONMENTS
The integration of sodium acetate in concrete for protection against extreme weather conditions Concrete cured in extreme hot or cold conditions can be significantly strengthened by adding sodium acetate to the mix, a new study shows. Mazen J Al-Kheetan of the Civil and Environmental Engineering Department at Mutah University, Jordan and Seyed Hamidreza Ghaffar and Mujib M Rahman of the Department of Civil and Environmental Engineering at Brunel University London report.
he influence of extreme weather conditions on concrete, either when it is fresh or matured, have been T reported to cause serious problems to the body of the concrete structure. Extremely high temperatures, for instance, increase the evaporation rate of water that is necessary for hydration process, which leads to crack propagation and strength reduction. Likewise, placing concrete under cold weather conditions will initiate cracks in conjunction with spalling and strength reduction due to the early frost of concrete. Therefore, protecting concrete structures that are exposed to cold or hot environments is a necessity to reduce their deterioration rate and extend their service life. Accordingly, researchers at Brunel University London and Mutah University in Jordan have presented a new line of Figure 1: Schematic illustration of the interaction and research where sodium acetate-based bonding between sodium acetate and concrete. cementitious material has been integrated within concrete to enhance its resistance against severe environmental conditions. them to fend off excess water from the pores Interestingly, curing control samples under The performance of the treated concrete and increase its impermeability. high temperature of 60°C did not induce was evaluated when cured under a freezing The formation of sodium acetate inside any evident microcracks in concrete (Figure temperature of −25°C and a hot temperature the pores of concrete and the effect of harsh 2b). However, an obvious wearing effect for of 60°C. Mechanical properties, water environment on its functionality within temperature rise was observed on the tested absorption and microstructural analysis of concrete were investigated through SEM. cross-sectional areas, where a weak bond concrete integrated with sodium acetate were Figure 2 shows untreated concrete (0% of developed between hydrated cement particles evaluated by conducting the compressive sodium acetate) after its exposure to both and aggregates. strength test, initial surface absorption test extreme environments, this was carried out Incorporating sodium acetate as an (ISAT) and scanning electron microscope to better interpret the effects of such curing admixture within concrete has led to an (SEM) analysis, respectively. conditions on the microstructure of concrete. improved microstructure of concrete The core of the proposed treatment (see As illustrated in Figure 2a and b, extreme when cured under extreme environmental Figure 1) depends on the dual functionality curing conditions have negatively affected conditions (see Figure 3a and b). of the material. Sodium acetate absorbs water the control samples, where freezing As shown in Figure 3a, incorporating to form crystals that settle inside the pores to condition (−25°C, Figure 2a) has led to the the sodium acetate within the concrete has line them. The formed crystals were found to introduction of some microcracks through greatly reduced crack propagation when develop hydrophobic properties that enables the internal parts of the concrete samples. concrete is under freezing conditions.
www.concrete.org.uk June 2020 concrete 31 Figure 2: Morphology of untreated concrete after its curing Figure 3: Morphology of concrete incorporated with sodium under extreme conditions of: (a) −25°C (100×, 5000× and acetate and cured under extreme conditions of: (a) −25°C (1000×, 10,000×) and (b) 60°C (500×, 5000× and 10,000×). 5000× and 20,000×) and (b) 60°C (1000×, 5000× and 20,000×).
Additionally, the presence of sodium acetate has led to development of a denser microstructure compared with control samples in Figure 2a. The integration of sodium acetate in concrete while curing it at 60°C has helped in reducing the weathering effect of high temperatures (Figure 3b). The high distribution of sodium acetate crystals within concrete and its high resistance to heat (>300°C) has resulted in preserving the internal structure of concrete from debonding and the reservation of the hydration products from weathering. Protective material The effect of sodium acetate as a protective material on the permeability of concrete, when exposed to extreme environmental conditions, was determined through the ISAT (BS 1881-208(1)) method. Water absorption properties were assessed after 28 days of curing under extreme temperatures of −25°C and 60°C. As shown in Figure 4, adding 2% of sodium acetate to concrete with a water:cement (w/c) ratio of 0.32 managed to reduce the water absorption rate by 79% when cured at 60°C (compared with control sample). Moreover, adding the same dose of sodium acetate led to the preservation of water absorption rate of concrete with w/c ratio of 0.32 when cured at −25°C. The high resistance of concrete to both Figure 4: Water absorption rate at 28 days for concrete with (a) w/c = 0.32 cured under −25°C, (b) w/c = 0.32 cured under 60°C, (c) w/c = 0.46 cured under −25°C and (d) w/c = 0.46 cured under 60°C.
32 concrete www.concrete.org.uk June 2020 Figure 5: Compressive strength of concrete after: (a) curing under −25°C for 7 days, (b) curing under −25°C for 28 days, (c) curing under 60°C for 7 days and (d) curing under 60°C for 28 days.
Further reading: extreme curing conditions when treated with either by 2% or 4%, with w/c ratio of 0.32 led 1. ORTIZ, J., AGUADO, A., AGULLO, L. and GARCIA, T. the 2% sodium acetate (Figure 4a and b) can to increase in concrete’s strength at seven and Influence of environmental temperatures on the be explained by: 1) the demand of 2% sodium 28 days despite the extreme curing conditions. concrete compressive strength: Simulation of hot and acetate to water to form its crystals is less than Adding 4% sodium acetate increased the cold weather conditions. Cement and Concrete Research, Vol.35, No.10, October 2005, pp.1970–1979. the demand of the 4% dose, which makes strength of 0.32 concrete by more than 2. ALSAYED, S. and AMJAD, M. Effect of curing conditions the available water during high-temperature 64% (compared with control samples) even on strength, porosity, absorptivity, and shrinkage of curing enough to continue the hydration after its curing in hot conditions. Moreover, concrete in hot and dry climate. Cement and Concrete process and, at the same time, activating the adding 2% sodium acetate to concrete with Research, Vol.24, No.7, 1994, pp.1390–1398. 3. AL-KHEETAN, M.J., RAHMAN, M.M. and crystals of sodium acetate; 2) the presence of a w/c ratio of 0.46 worked on preserving its CHAMBERLAIN, D.A. Fundamental interaction of sodium acetate crystals in the pores, during strength when exposed to cold temperature hydrophobic materials in concrete with different low-temperature curing, will help in reducing and increased it by 8% when exposed to high moisture contents in saline environment. the thermal gradient through concrete, temperature (both after 28 days of curing and Construction and Building Materials, Vol.207, 20 May 2019, pp.122–135. which will decrease the internal pressure compared with control specimens). These 4. AL-KHEETAN, M.J., RAHMAN, M.M. and inside the pores; and 3) the formation of results reflect the influence of treatment on CHAMBERLAIN, D.A. Optimum mix design for enough organosilicon bonds inside the pores concrete and its ability to combat extreme internally integrated concrete with crystallizing of concrete that are capable of reducing the harsh conditions, as treatment participates in protective material. Journal of Materials in Civil Engineering, Vol.31, No.7, July 2019. absorbed water either after high-temperature making the concrete’s structure denser with 5. RYOU, J, and LEE, Y. Use of tabletting & coating curing or low-temperature curing. minimum microcracks (see Figure 3). accelerator for the prevention of early-frost of This discovery will facilitate the use of concrete in cold weather. Cold Regions Science and Influence concrete protection materials in fresh state, Technology, Vol.87, March 2013, pp.1–5. 6. AL-KHEETAN, M.J., RAHMAN, M.M. and The influence of curing different concretes eliminating the need to apply traditional CHAMBERLAIN, D.A. Influence of early water exposure at extreme temperatures on the compressive protection, which has often shown on modified cementitious coating. Construction and strength properties was assessed at seven inconsistent performance. It will also reduce Building Materials, Vol.141, June 2017, pp.64–71. and 28 days. As highlighted in Figure 5, the number of maintenance procedures 7. AL-KHEETAN, M.J., RAHMAN, M.M. and CHAMBERLAIN, D.A. Influence of crystalline admixture the addition of sodium acetate has greatly required to increase the lifetime of concrete on fresh concrete to develop hydrophobicity. enhanced the protection level of concrete or masonry structures, reducing long-term Transportation Research Board 96th annual meeting, under extreme conditions, without any drop expenditure. No.17-02487, 2017. in compressive strength observed, when added 8. AL-KHEETAN, M.J., RAHMAN, M.M., MUNISWAMAPPA, Reference: B.N. and CHAMBERLAIN, D.A. Performance to concrete with a high w/c ratio. Moreover, 1. BRITISH STANDARDS INSTITUTION, BS 1881-208. enhancement of self-compacting concrete in saline sodium acetate increased the strength of Testing concrete. Part 208 – Recommendations for the environment by hydrophobic surface protection. concrete when added to concrete with a low determination of the initial surface absorption of Canadian Journal of Civil Engineering, Vol.46, January w/c ratio. The addition of sodium acetate, concrete. BSI, London, 1996. 2019, pp.677–686.
www.concrete.org.uk June 2020 concrete 33 GLASS-FIBRE-REINFORCED CONCRETE GRC stud-frame construction – an overlooked opportunity Stud-frame construction is often overlooked when producing and installing glass-fibre- reinforced concrete (GRC), despite offering a superior solution. GRC with embedded stud-frame construction offers savings in both substructure costs and a heavily reduced mounting time. Here, Nikolaj Ringberg Brandt of BB fiberbeton argues the case for stud-frame construction and discusses the various systems for its installation.
RC can be shaped into almost any thinkable form to accommodate the architectural needs of a G project. Many finishes can be achieved by adding iron dioxides to the slurry, exposing aggregate after casting, and by applying matrices to the mould. These qualities – together with the lightweight nature of GRC and its sustainability and durability characteristics – drives the large increase in popularity of the material, with both architects and builders (see Figure 1). Today, a range of fixing systems exists for GRC, with almost all of them allowing for hidden fixing. However, it is difficult for designers and installers to decide which fixing Figure 1: Geometry and surface option with GRC. system to use for a project. A stud-frame construction can prove to be a superior option to other solutions.
Caption
Caption Caption
Caption Caption Caption
Figure 2: Recess used as part of Figure 3: Solution developed for Figure 4: Bracket cast into back of fixing system, FA1000-system. a project in London. GRC in Copenhagen, Denmark.
34 concrete www.concrete.org.uk June 2020 GLASS-FIBRE-REINFORCED CONCRETE
Figure 5: Bracket mounted to Figure 6: GRC stud-frame GRC, Bratislava, Slovakia. construction.
Figure 7 (right): Anchor attached to GRC. (Image: GRCA.)
Fixing options substructure and GRC become one element GRC is generally mounted with hidden (Figure 6). With this method, only a few fixings. Grade 18P GRC, the highest grade mounting points (usually four or five) are according to the International Glassfibre needed to attach the GRC to the building. Reinforced Concrete Association, (GRCA), With GRC stud-frame construction, the is produced by spraying GRC into GRC element is typically 12mm thick and horizontally placed moulds, making it easy to attached to a bespoke, prefabricated metal cast in inserts or brackets on the back of the frame (typically HDG steel), using L-shaped elements. anchors in stainless steel (Figure 7). These Furthermore, the moulds can be anchors are often placed at 600mm intervals manufactured with recesses, to allow for and with correct positioning and design, they fixing using the sides or bottom of the GRC act both for wind (flex) and weight (gravity) elements (Figure 2). However, all types of anchors. Placement and embedding of the inserts, brackets and recesses vary. Many anchors allow the correct degree of rotation projects develop their own fixing system, and moisture movement. increasing the costs of design and production, GRC stud-frame construction with and uncertainty during installation can also an embedded steel frame is a hybrid become a problem (see Figures 3 and 4). construction, where each part needs to With some projects it is necessary to adapt function statically (individually and together). the chosen fixing, due to the structure of It is recommended that this is ensured by the building, although in most cases tested using finite-element analysis software. The solutions can be used. responsibility for this lies with the GRC Solutions originating from fixing other manufacturer, who has responsibility for the materials, such as natural stone, have been quality, lifespan and statics of the entire GRC used for GRC projects, such as an aluminium stud-frame construction (see Figure 8). subconstruction with a matching C-bracket A further important consideration is attached to the GRC (Figure 5). This choosing the correct type of steel for a project. solution requires an expensive and time- A stud frame will allow for easy handling consuming subconstruction and the through all stages of construction: on-site; mounting of the GRC is more cumbersome on the production line; during demoulding; when trying to get all C-brackets attached at quality control; and transportation. the same time. Getting started Stud-frame construction “The use of stud-frame construction is An alternative fixing is stud-frame often the most economical and preferred construction, where the substructure method for constructing medium to large is embedded into the GRC; here the panels… At the other end of the scale, stud-
www.concrete.org.uk June 2020 concrete 35 GLASS-FIBRE-REINFORCED CONCRETE
frame construction can often simplify the production and fixing of small panels…”(1) Basically, it often makes sense to use the stud- frame option. Stud-frame construction is suitable for small elements, due to fixing, and for medium and large elements for both economy and fixing. The design calculations for GRC stud-frame construction are usually made by the manufacturer, rather than the architect, designer or installer. Complexity of the solution should therefore not deter designers from applying it to their projects – instead, the benefits of stud-frame construction should allow more projects to use the method for its fast-mounting capabilities, coupled with its requirement for much less subconstruction (see Figures 9 and 10). The current push within the construction industry to use more prefabricated materials to limit on-site work may lead to a rise in the use of GRC stud-frame elements. Informing architects and designers of the option of stud-frame construction and ensuring that they specify their requirements to GRC manufacturers during the early phase of design, are key to further growth in the use of the method. The future could see stud-frame construction becoming the default solution for GRC, with the associated cost benefits, for many building projects in the coming years. Reference: Figure 9: GRC stud-frame element, 1. INTERNATIONAL GLASSFIBRE REINFORCED Sky Park by Zaha Hadid Architects. CONCRETE ASSOCIATION. Practical Fixing Guide for Glassfibre Reinforced Concrete (GRC). Version 1.1, (Photo: KUDIVANI Photography.) GRCA, March 2018, available at: https://grca.org.uk. Figure 10: Example of GRC stud-frame element, Priorn, Malmö, Sweden.
Figure 8: Finite-element analysis, Sky Park by Zaha Hadid Architects.
36 concrete University Certificate in Concrete Technology
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• This on-line course has been developed by University This course is open to all with an interest in concrete of Derby with The Concrete Society and the Institute of particularly; Quarrying - so you can be sure you’re learning relevant • anyone within the industry wishing to gain formal and up to date information. recognition of their experience. • On successful completion you’ll gain a nationally • supervisors, managers and support personnel wishing recognised qualification, a Level 4 University Certificate to gain wider knowledge of the science of concrete in Concrete Technology, which will help your career and its properties. development. • Conveniently delivered, on-line and at the University of Derby Enterprise Centre over one year, this course is the ideal launch pad for further study in Concrete Technology. How to apply • Graduates of this course will be eligible to apply for For more information: Membership of the Institute of Concrete Technology Email: [email protected] at Associate level. Tel: 01276 607140 www.concretequalifications.org/qualifications.asp The course starts in September so apply early to ensure all course For further advanced concrete related qualifications at the University of Derby, please visit the University of materials are received Derby website www.derby.ac.uk in good time.
The Institute of Quarrying Fantastic façades – GRC comes of age in the UK Pioneered by architects in the commercial property sector, glass-fibre-reinforced concrete (GRC) is finally showing off its creative credentials within the European housing market. James Butler of London-based Pura Façades looks at the material’s rise to prominence among top-end house builders.
he UK’s first major use of GRC Credentials Above left: Bridge was probably an office block near Clearly, architects and builders enjoy working House, Muskoka, to St Paul’s in the city of London. with GRC, thanks to its ease of handling Canada. T Originally the UK headquarters (due to its lightweight properties), its good of Crédit Lyonnais, the eye-catching, four- environmental credentials (less material used) Above: Heath Lodge, storey office development was designed by and the impressive creative possibilities it London. architect Whinney, Son & Austen Hall. The brings to projects. building was refurbished in 2013, when it was The material comprises high-strength, granted Grade II listed status, due to its ‘value alkali-resistant glass fibres, which are and contribution to the built environment’. embedded into a concrete matrix. These Approximately a decade before this fibres act as the main load-carrying redevelopment, the building (which was then component, while the surrounding matrix over 25 years old) underwent various safety keeps them in position, and transfers load tests, with special attention paid to the GRC between the fibres. Both fibres and matrix are material and its integrity. Building engineers good at retaining their physical and chemical concluded that the external concrete cladding identities, combining these properties to was in such good condition that its lifespan create a high-performance composite. was effectively indefinite. GRC had arrived This differs from traditional precast – and architects soon started considering it concrete, which uses steel as the main load- as an ideal replacement for the much heavier carrying element. While this works well in precast concrete. the medium term, steel has a tendency to Since then, the lightweight material has corrode, leading to potential structural issues, been used more and more, with many iconic sometimes within a couple of decades. buildings in the UK using GRC instead of GRC is usually manufactured in thin traditional precast, brickwork, rendering or sections, by machine-spraying an enriched stonework. Exact figures are hard to come by, grade of cement and aggregate mix with glass but most market studies suggest that GRC fibres dispersed throughout. These fibres has been on an upward trajectory in the UK serve a similar purpose to steel reinforcement – growing year-on-year by more than 10% in concrete with the big difference being that recent times. fibres do not rust.
38 concrete www.concrete.org.uk June 2020 Private spa, Austria.
Examples of private developments that show what can be achieved with GRC: • Villas in Grünwald, Germany – The juxtaposition of these bold colours and A relatively recent innovation is the use of sandwich form and provide exceptional shapes creates a strong architectural glass-fibre fabric to reinforce the concrete. durability, fire resistance, weather resistance, statement on the south-western side This method achieves the same structural and sound insulation properties. of Munich. Designed by architect Titus strength as the traditional, sprinkled glass- Indeed, given the repercussions of the Bernhard, these two striking family homes fibre system, but enables the GRC to be Grenfell Tower fire, architects and developers use Rieder öko skin slat wall panels. much thinner – and lighter. While the older are now taking a ‘belt and braces’ approach • Alpine spa in Austria – GRC can be used method requires the sprayed GRC to be to safety, increasingly relying on GRC to to create a more natural effect, as seen between 40 and 100mm thick, the fabric contribute to a non-flammable A1 fire rating with this garden spa room in Maishofen, alternative uses a much thinner, lighter layer for buildings. Austria. This innovative use of tough GRC of GRC of only 13mm. What’s more, this In the UK, we work closely with Rieder, creates a hardwood effect, with none of thinner GRC system still reaches the highest the award-winning Austrian manufacturer of the maintenance or treatments required testing level for impact resistance. GRC. Certainly, in the UK we have plenty of for tree products. excellent examples of this material being used • Family home in Austria – this unusual Key benefits of GRC to provide stunning façades on stand-out application of GRC shows how it can be GRC panels are typically used to create a commercial developments. Recent projects used internally to make a strong design lightweight cladding system and can be made include Heath Lodge homes in Ealing, statement. Here, GRC is used to create to look almost identical to natural stone or London, and modern apartments in the a central piece of furniture that divides even wood. Installation is easier and more village of Crowthorne, Berkshire. the room. Glass-fibre concrete with cost-effective due to the lower weight of the Other projects recently completed on various colours was used for the chimney panels, which is 75–80% lighter than precast- mainland Europe demonstrate the huge and panelling and the kitchen worktop. steel-reinforced concrete cladding. as yet, untapped potential for this material Given the importance of sustainability within the house building sector in the UK. • Bridge House in Muskoka, Canada – for for new housing developments, recent tests With well-established examples such as the façade of this exquisite building, showing that GRC is an energy-efficient the aforementioned Crédit Lyonnais building the architect +VG used öko skin slats in building material, which is capable of in St Paul’s, GRC has proven its credentials as silver grey. The building is harmoniously achieving a BREEAM A+ material rating, is a hardwearing building façade. More recently, integrated into its surroundings within a an important point to note. innovations in its design have seen it become pine forest and next to a lake. far more lightweight – reducing the amount Let’s get creative • Affordable housing in King’s Cross of material used in the manufacturing process conservation area, London – this award- Increasingly, we are seeing architects and and facilitating far easier panel placement winning project from architect Jestico designers taking the experience they have during the construction phase. & Whiles has space for 156 affordable gained from large commercial developments With an almost endless range of natural and sustainable houses in a nature – such as public buildings, office blocks and colours and textures, GRC enables architects conservation area. Climbing plants and universities – and applying this creativity to and designers to explore their creativity fully. green roofs help the buildings to blend private housing. Certainly, the trend towards sustainable, harmoniously into the surrounding GRC panels can be created to replicate natural buildings is a huge influence within landscape. Rieder öko skin slats produced complex profiles, giving the appearance of modern housing – and the new generation of in a special colour were used for the much heavier and expensive stonework. lightweight GRC is a key building block of façade. These panels generally take a ribbed or this movement.
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