concreteTHE MAGAZINE OF THE CONCRETE SOCIETY Volume 54 July 2020 Issue 06

Visit: www.concrete.org.uk

‘Modern and comfortable living’ Concrete’s versatility shown at Barrow House

Historic concrete Low-carbon construction The Isokon building, Hampstead Cement opportunities

Contents

3 From the Editor 4 World News 6 Society News

Batching Plant, Concrete Equipment 8 Exploring the impact of engine idling Karl Rudman 10 Modular design batching plant Concrete report

Ready-Mixed Concrete 12 Keeping concrete construction moving in the face of Covid-19 Helen Frape 14 Structural concrete in a zero-carbon future Paul Astle 16 Concrete and contracts: design responsibility Lucinda Robinson and Jesse Way

Water-Resistant Construction 18 A systematic approach to designing a below-ground waterproofing solution Simon Morris 21 How can we use the indisputable laws of physics to our advantage? Alex Burman

Glass-fibre-reinforced Concrete 24 Biophilic design: connecting GRC to nature Bernhard Stömmer

Historic Concrete 26 The Isokon or Lawn Road Flats, Hampstead: A Modern masterpiece Edwin Trout 30 Telegraph Hotel set to become icon of Coventry’s cityscape Sophie Davies

Architecture and Design 34 Barrow House, Lincolnshire Concrete report 36 Grey supporting green Elaine Toogood

Low-carbon Construction 38 Low-carbon cement opportunities Nina Cardinal

40 Features List/Ad Index/Subscriptions concrete magazine is produced in-house by The Concrete Society, The July 2020 cover a not-for-profit, independent membership organisation dedicated to The East Midlands’ only Area of supporting the use of concrete, the most widely used building material in Outstanding Natural Beauty, the the world. CoverLincolnshire StoryWolds, has some of the region’s most beautiful scenery, Established in 1966, and with members from around with rolling hills, hidden valleys and the world, The Society has built on its technical base quaint villages. Now, this rural haven to become a leading provider of information, serving also boasts the 2019 Local Authority the needs of clients, architects, engineers, specifiers, Building Control ‘Best Individual suppliers, contractors and users of concrete. New Home’, Barrow House. See page 34. Visit: www.concrete.org.uk

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. AWARDS AWARDS20202020

Congratulations to the 2020 Shortlist from which the winners will be chosen NOMINATED BY

ENGLISH NATIONAL BALLET, LONDON BANAGHER PRECAST CONCRETE

LOCAL BLACKFRIARS, SALFORD, GREATER MANCHESTER TECHRETE UK

LONDON CITY AIRPORT, LONDON BAM NUTTALL

NORTH LONDON RESIDENCE, LONDON DECONSTRUCT (UK)

SOBORO, LONDON KENNEDY TWADDLE

ST PAUL’S SCHOOL - GENERAL TEACHING BUILDING, LONDON WALTERS & COHEN ARCHITECTS

THE MARSHALL BUILDING, LONDON GETJAR LTD THE STANDARD, LONDON ORMS TOWN HOUSE AT KINGSTON UNIVERSITY, KINGSTON UPON THAMES GRAFTON ARCHITECTS

UNIVERSITY OF ST ANDREWS MUSIC CENTRE, ST ANDREWS, SCOTLAND STEPHENSON CONSTRUCTION (NORTH)

WOOD LANE ELECTRICAL SUBSTATION, LONDON ANDREWS ASSOCIATES

Premier sponsor www.concrete-awards.org.uk For further information about The Society Awards email: [email protected] or call: 01276 607140

Supporting sponsors FROM THE EDITOR

EDITOR: James Luckey Tel: +44 (0)1276 607158 [email protected]

EDITORIAL ASSISTANT: Helen Marney Tel: +44 (0)1276 607159 Hiding to nothing [email protected]

TECHNICAL ADVISOR: Who’d be in Government? Certainly the past few months have been the hardest Richard Day for politicians to navigate the country through and it is unlikely that MPs from any DESIGN: colour of the political spectrum ever thought they’d have to deal with such seismic Darryl Killoran times. Add to that the curious societal expectation that our legislators always SALES REPRESENTATIVE: achieve professional perfection and it’s easy to see why being in Government is a Fred Combe hiding to nothing. Tel: +44 (0)20 3859 7097 [email protected] or every positive development, industry bodies queuing up with demands for James Pembroke Media Ltd is for example paying the wages of more money, reform and tax relief. The Concrete Society’s appointed advertising sales agency. employees and self-employed, there Supply chain delays, labour shortages and F are at least two negatives – a slow cashflow with dwindling reserves are likely SUBSCRIPTIONS MANAGER: testing regime and lack of PPE. One step up to be the biggest barriers to construction Val Goddard and two steps back, it seems. progress in the months ahead. This is why the Tel: +44 (0)1276 607149 But dealing with a global situation Government has faced calls for: a reduction [email protected] unprecedented in human experience (or at in VAT on repair and maintenance work; a least modern experience) was always going national retrofit strategy (from the Federation concrete is published 10 times a year (2020) and sent free to all Concrete Society members. to be subject to make-it-up-as-you-go-along of Master Builders); major reforms to the Annual prepaid subscriptions for 2020: policy, albeit with the hope that lessons are CITB in order to support sector skills (by UK £125, Europe £150, outside Europe £170 learned for the future. the National Federation of Builders); and (prices inc. p&p). Single copies and back issues: £15 (exc. p&p). Coping with the aftermath, putting reform of the mineral planning system (by the the economy and life in general back Mineral Products Association). THE CONCRETE SOCIETY together again after major disruption – well, And that’s all before individual President: humankind has long experience and one organisation’s demands for stamp duty cuts, Deiniol Williams would hope that it is surer ground for our safer sites to include more biometrics and politicians. longer site hours during the summer. That’s Managing Director: So, it will be interesting to watch quite the shopping list. Kathy Calverley MBE developments over the coming weeks and There’s every reason to hope and believe The Concrete Society, months to see the policy decisions made to that many of these calls will be listened to Riverside House, 4, Meadows Business Park, restore health – both personal and economic sympathetically. After all, the speed at which Station Approach, Blackwater, – to the country. the industry recovers will depend much on Camberley, Surrey GU17 9AB, UK Tel: +44 (0)1276 607140 As with the previous recession, the Tor y Government stimulus packages, as well as Fax: +44 (0)1276 607141 administration has already made moves for sector confidence. e-mail: [email protected] the country to build its way out of trouble But in juggling all this and similar calls www.concrete.org.uk and the fact that construction was the first from other industries (and at some point,

Printed by Bishops Printers industry encouraged back to work during the country has to pay for it all too), being in Portsmouth, Hampshire lockdown is surely a sign that its importance Government is a hiding to nothing indeed. © The Concrete Society, 2020 is recognised. Enjoy the issue! ISSN 0010-5317 Although it may seem an age ago, the Budget in March made a pledge of Neither Concrete nor The Concrete Society are gargantuan investment in infrastructure, responsible for the statements made or the opinions with around £640 billion for roads, railways, expressed in this journal by third parties and communications, schools, hospitals and organisations. power networks across the UK by 2024–25. Added to that were further billions for James Luckey, Editor housing and flood protection. Tel: 01276 607158 A further sign of ‘normal’ life returning is [email protected]

www.concrete.org.uk JULY 2020 concrete 3 WORLD NEWS

NEWS IN BRIEF Heat-treated fly ash may „ UK • Obituary The Concrete Society is sad to hear improve geopolymer of the passing of past President Tony Cusens, who held office from 1983 to 1984. Tony died on 30 May at the age concrete alkali attack levels of 93. A full obituary will be published RESEARCHERS at the University exposed to highly alkaline mediums, in the September issue of Concrete. UK concrete pour of Johannesburg have found that such as some chemical storage high-temperature heat treatment facilities. The findings of our new record at Hinkley „ Portugal • Symposium can reduce low resistance to extreme study show that the alkali resistance OPERATIVES building the Hinkley The fib Symposium 2021 will be held alkali attack in fly ash geopolymer of geopolymer concrete can be Point C nuclear power station have in Lisbon, Portugal on 14–16 June 2021, concrete by half, improving its significantly improved by exposing it completed the 49,000-tonne base gathering together professionals, durability. to an elevated temperature, optimally researchers, and students from all for the station’s second reactor Fly ash generated by coal-fired 200°C,” added Dr Naghizadeh. over the world to discuss ‘Concrete on schedule. The power station in power stations creates groundwater In the research published in Case Structures: New Trends for Eco- Somerset will produce reliable low- and air pollution from vast landfills Studies in Construction Materials, Efficiency and Performance’. Keynote carbon electricity. and ash dams. Some of the waste blocks of fly ash geopolymer mortars speakers will address the three most The final concrete pour of 8991m3 product can be repurposed into were variously heat cured at 100, relevant topics: fib Model Code 2020, set a new UK record for a single, geopolymer concrete, such as precast 200, 400 or 600°C for six hours. sustainable concrete and high- continuous pour. It surpasses by heat-cured elements for structures. These were then immersed in water, performance structures. 37m3, the previous record during “In a previous study, we found that a medium-alkali medium or an construction of the base for Hinkley's fly ash geopolymer concrete can be extreme-alkali medium and stored at first unit in June 2019. Hanson UK „ Global • Appointment vulnerable under extreme alkaline 80°C for 14 or 28 days, depending on The Global Cement and Concrete supplied the raw materials for the conditions,” said Dr Abdolhossein the performance measurement. Association (GCCA) has appointed concrete to main civils contractor Naghizadeh. The study forms part Although the use of geopolymer Dinah McLeod as CEO, to succeed BYLOR. This milestone was completed of Naghizadeh’s doctoral research at cement is growing every year, Benjamin Sporton who leaves at the by teams who have had to adapt to the Department of Civil Engineering its application is still very small end of July. McLeod most recently new coronavirus working conditions. Science at the University of compared with Portland cement. served as a director of ‘The B Team’, a Their achievement, known as Johannesburg. Geopolymer has been used as the standard-setting non-profit initiative, ‘J-zero’, comes less than a year after “The recommendation from the binder in residential structures, which was established to improve the completion of the first reactor’s study, was that this material should bridges, and runways throughout business practices to enhance the well- base in June 2019. Construction during not be used in structures that are the world. being of people and the planet. She has the current coronavirus crisis was previously held senior sustainability able to continue by reducing numbers roles with the Overseas Development Data sharing lifts reinforcement on-site to enable social distancing and Institute and in the private sector with concentrating on the critical areas of BT, Novartis and Allianz. confidence levels says CARES construction. Where social distancing is not possible, workers have been „ UK • Appointment BUSINESS during the global pandemic the adoption of the CARES Cloud. using extra protective equipment. Breedon Group has appointed has triggered acceleration in the pace “With the universal requirement to Donna Hunt as its first group head of of digital transformation, according to share data, following the coronavirus Consultation on sustainability. Hunt has held several the steel certification service CARES. outbreak, we have seen quite a senior sustainability, environmental With steel mills and fabricators marked movement towards the multi-storey builds and stakeholder engagement suffering either enforced lockdowns adoption of digital solutions,” added THE Government has undertaken a positions across the energy, aerospace or restricted production under virus Brankley. “We had launched our consultation on proposals to reduce engineering and construction materials mitigation measures, virtually all digital platform prior to lockdown the maximum height of timber- sectors. She will be responsible for testing and assessment of reinforcing and believe there will be rapid framed buildings from six storeys developing and implementing an steels is being conducted remotely by pick-up in its use, particularly to four. The ‘Building a Safer Future’ effective sustainability strategy to the CARES audit team. as specifiers are setting out the consultation proposed reforms to shape the group’s practices. This has led to a rapid switch assurance requirements products England’s current building safety to new ways of working. Auditors must meet on major projects. Indeed regulations following the Grenfell France • Sustainability are conducting assessments and BEIS is backing a pan-industry plan „ Tower tragedy. Initially, it was to LafargeHolcim has extended its interviewing manufacturers via a to change priorities that govern examine the prohibition of using partnership with US-based cement and range of online platforms and digital how we view and run infrastructure combustible cladding systems. concrete technology company Solidia tools have replaced paper, according and says digitalisation, built on However, a series of timber building Technologies until 2025. Together, to Lee Brankley, CARES CEO. secure, resilient data sharing, has an fires resulted in calls to ban the use the two companies’ solutions emit But the biggest change has been important role to play.” of combustible materials for multi- up to 30% less CO2 during cement production and capture and store storey building structures. Steve Elliott, chair of the British CO2, leading to a 70% carbon-reduced MPA UK Concrete, the group representing the UK concrete industry, has Association of Reinforcement, said, concrete. The partnership will continue published its framework to help inform the delivery of an ambitious roadmap “Unlike reinforced concrete, which to develop new solutions focused on for the UK concrete and cement sector to deliver net negative emissions by non-reinforced concrete structures and 2050. In preparing the roadmap, UK Concrete is exploring the use of existing and provides up to six hours of inherent paving, while also aiming to make it emerging technologies including energy efficiency, fuel switching, low-carbon fire resistance and structural integrity, increasingly applicable for structural cements and concretes, and carbon capture, usage or storage to deliver the timber frame offers 30 minutes. The applications. Government’s net zero target. consultation must recognise the simple fact: timber burns.”

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SOCIETY NEWS Members’ library at RECENTLY ADDED The Concrete Society Sarah Gerrard and Edwin Trout look at a recent addition to the library, as well as some highlights from The Society’s historical collection.

HIGHLIGHTS FROM THE COLLECTION

Historical patents pieces are afterwards to be reduced to powder Joseph Aspdin’s 1824 patent for Portland by grinding… and then the composition is in a cement is by far the most famous in the state fit for use.” evolution of modern concretes, but it is by In 1822, James Frost patented a material Design of Reinforced Concrete Buildings no means the only one. The Society’s library he named ‘British Cement’: “I select such for Seismic Performance: Practical has a small collection of copies of historically limestones or marls… as are entirely or Deterministic and Probabilistic interesting patents from the 19th Century and nearly free from any admixture of alumina or Approaches others of more recent vintage that cover a argillaceous earth, and contain from 9 to 40% This is a substantial book that aims to “offer wider variety of innovations. The former are set of siliceous earth, or silica, or combinations simple and effective approaches for performance- out in a C&CA Library Record of 1949, entitled of silica and oxide of iron, the silica being in based seismic design that are an anchored in The first hundred years of patents on cement and excess and in a finely divided state, and break theory (and observation) and which promote its manufacture. such selected materials into small pieces, intuition about structural behaviour”. It is Of these, James Parker’s patent of 1796, which are then calcined in a kiln… until all written for both students and those practising for the first commercially successful cement, carbonic acid be expelled and… the calcined earthquake-resistant structural engineering and described his discovery in outline only: “The material is to be ground to a fine powder.” can be used as a foundation text, offering what is needed to understand the essentials of the field. stones of clay or noddles of clay are first But it is Joseph Aspdin’s patent that is the Practical design guidance to address single or broken into small fragments, then burnt in a most famous of its kind by far and the direct multiple seismic performance levels is presented kiln or furnace… with a heat nearly sufficient progenitor of the present Portland cement here, using the latest tools and techniques, to vitrify them, then reduced to a powder manufacturing industry. However, its wording including MATLAB. The 19 chapters are arranged by any mechanical or other operation and is obfuscatory, whether by design or oversight, into five sections: introduction; seismic demands; the powder so obtained is the basis of the and no useful information is supplied regarding essential concepts of earthquake-resistant cement.” the relative proportions of limestone and design; reinforced concrete systems; and design On its expiry in 1810, Edgar Dobbs entered clay, the kiln temperature, the duration of methods and examples. The fourth section covers component proportioning and design based on the market with a patent setting out a firing or the fineness of grinding. Significantly, ACI 318, component proportioning and design revised process: “First, I reduce the lime or however, it does introduce a material that has requirements according to Eurocodes 2 and 8, and its carbonates to a fine state of division, been marketed continuously since as Portland component modelling and acceptance criteria. the lime by slacking, and the carbonates cement. „ Several distinct design methods are identified in by grinding them, whether chapter 18 and illustrated as examples in chapter with or without water, by 19. References for each chapter, three appendices the common methods used and an index are included. for grinding… I take certain CRC PRESS, 2019, 576 PAGES portions of the washed lime or its carbonate… and mix and incorporate them well together in a vessel or other receptacle fit for the purpose; or the incorporation may be made by adding to the bodies in their natural state a Aspdin’s patent for Portland small quantity of water and cement of 1824. then grinding and tempering them till they become homogeneous and plastic. [He describes burning the Contact The Concrete Society for more details: material in a kiln.] The burnt Tel: 01276 607140 or e-mail: [email protected]

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BATCHING PLANT, CONCRETE EQUIPMENT

Exploring the impact of engine idling Concrete mixer trucks operate under strenuous and unique conditions that can be tough on the vehicle’s engine. Often stationary when in use, regular engine idling can result in increased wear rates, as well as unplanned downtime and maintenance. Karl Rudman of Petro-Canada Lubricants reports.

hen not managed during 100°C due to reduced engine loading. The planned maintenance accumulation of water also increases the scheduling, downtime can risk of acid formulation and fuel dilution in W cause operational disruption addition to reducing the oil viscosity. These and affect a business’s bottom line. Fleet factors contribute to the acceleration of the managers must be incredibly careful to ensure rate of engine wear, while shortening oil drain the reliability, efficiency and safety of their intervals. equipment, even in extreme conditions. The volatility of oil also increases when Many factors can impact fuel economy excessive fuel dilution occurs, meaning that and equipment performance. By proactively soot can find its way to the diesel particulate addressing the hidden impact of prolonged filter (DPF). Cleaning the DPF leads engine idling, managers can protect against to increased regeneration cycles, which the risks of unscheduled downtime and consequently means that fuel economy is lost. experience the benefits that enhanced Operators of all construction equipment reliability and fuel economy can offer. are subject to significant fuel consumption due to idling and it can be a costly Assessing the negative impact consequence. For example, according to some According to Komatsu, an average estimates, as much as one gallon of fuel is construction vehicle will spend 40% of its used each hour if a vehicle is left idling(2). time idling when in service(1). Given the However, if effectively managed, there unique requirements of a concrete mixer are untapped economic, financial and fuel truck, some vehicles may idle significantly economies to be found. longer than this. Idling time has a detrimental impact on Making the right lubricant choice the rate of engine wear, ie, one hour of idling The choice of engine lubricant can have a can have the equivalent effect of driving considerable impact on the protection of approximately 25 miles. This increases vital engine components, both positively the risk of oil temperature dropping below and negatively. Some level of idle time is

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inevitable for mixer trucks, but the correct enhancing additives, which offer a greater choice of high-quality lubricants can help level of protection in a variety of conditions. to mitigate the negative impact. Quality This means that synthetic oils are an effective lubricants reduce the pumping and rotational year-round solution for operators and do not losses of an engine, while also minimising need to be swapped to adapt to changing metal-to-metal contact between moving weather conditions. components. The right lubricant for the A lower viscosity oil can also reduce equipment and the conditions it operates the work rate of the engine, which can be in can protect the engine’s inner workings, especially beneficial for fleets operating in while also securing improvements in engine colder regions. These oils enable easier cold performance and fuel economy. starts and provide the required protection It is crucial that decisions are made for vehicles that idle frequently. Bringing after consulting the original equipment together these essential properties and also manufacturer's vehicle manual, or by the ability to enhance the protection of vital contacting the manufacturer directly to engine components and prevent engine discuss which product is most suitable for the wear are attributes that concrete mixer truck engine. operators should consider in order to counter the effects of engine idling. „ “According to Komatsu, an References: 1. JACKSON, T. How to save money and protect average construction vehicle will equipment by creating an anti-idling policy at your spend 40% of its time idling when construction company. Equipment World, April 2014, available at: https://bit.ly/2ZIAHsY. (1) in service . Given the unique 2. CENTRE FOR LOW EMISSION CONSTRUCTION. Anti- Idling Campaigns, available at: https://bit.ly/2XaSHup, requirements of a concrete mixer accessed May 2020. truck, some vehicles may idle significantly longer than this.”

The conditions that the equipment is required to work in, such as how the oil is used and the climate, must also be a key consideration when choosing a lubricant. Lubricants are available in different Society of Automotive Engineers (SAE) viscosity grades, which dictate the acceptable temperature range that they optimally perform in. The ‘W’ following the SAE viscosity grade stands for ‘winter’ and not ‘weight’, which is a popular misconception. This means that the oil is suitable for use in – and importantly, provides protection in – colder temperatures. Equipment working in warmer conditions may find that a heavier grade oil such as SAE 40 is more suitable due to its resistance to lubrication breakdown. The right grade of oil ensures adequate lubrication flow and subsequent protection of critical engine components. Exploring synthetic oils Operators can also use the benefits of synthetic oils. Full synthetic and synthetic blend engine oils possess better stability than conventional oils and are therefore more resistant to breakdown. Premium full synthetic oils are formulated with synthetic base stocks that are blended with high- quality and often unique, performance-

www.concrete.org.uk JULY 2020 BATCHING PLANT, CONCRETE EQUIPMENT Modular design batching plant Following a robust and highly competitive procurement process, Kent-based Reco ReadyMix has chosen and installed a new concrete batching plant at its depot in Sandwich, Kent. Concrete report.

apable of producing up to 115m3 been supplied with Liebherr’s Litronic per hour, the Mobilmix 2.5-F EMC control system. This intuitive system concrete batching plant includes enables the operator to single-handedly C a bank of four aggregate storage and accurately control the drum rotation containers with two that are split. Each direction, ensuring the correct amount of material is weighed and fed into a DW 2.5 material is delivered. twin-shaft mixer via a simple rope-operated Thanks to the system’s constant speed- skip. The twin-shaft mixer is capable of drive function, which reduces drum batching a maximum of 2.67m3. Heavy- revolutions during each delivery, drum duty mixer tools inside the body are driven service life is extended. The low weight of by a pair of 75kW motors, both mounted the drum means that a larger payload can be on the same side of the mixer for ease of carried without any reduction in the build access when servicing. The energy-efficient quality and longevity of the drum and drive planetary gearboxes reduce the plant’s energy unit. The generation 05 mixer series has requirements, ensuring a low production cost. benefitted from a number of recent upgrades The modular design meant that the designed to aid the driver: the swivel chute concrete batching plant was delivered and is now 80mm higher to allow a better flow Mobilmix 2.5-F concrete constructed in a matter of days. As the angle for the outgoing material and the batching plant. whole system is prewired, it only required ladder platform has been enlarged with a new, linking together and a connection to the lightweight aluminium ladder replacing the power and water networks on the site. While older steel version. the solution was not the cheapest, Reco’s past experience with the manufacturer’s Strategy equipment and service, which includes a Jay Preece, Reco ReadyMix general manager number of dozers and material handlers, and director, says, “Our growth strategy has swung the deal. been achieved by a concentrating on reliability and reinvestment in new facilities, vehicles Mixing drums and machinery. With an extensive range of To complement the batching plant, Reco modern machinery and equipment already ReadyMix has also purchased three HTM in our fleet, the new purchases have fitted in 905 mixing drums mounted on a mix of seamlessly. As with the batching plant, we Scania and Mercedes chassis. Each capable looked at several drum alternatives already in of handling a load of 8m3, the drums have operation around the south-east.” „

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 Keeping concrete construction moving in the face of Covid-19 Helen Frape of GCP Applied Technologies explains how concrete producers can maintain consistent concrete quality, while observing social distancing.

ince the global Covid-19 pandemic in the manufacture of ready-mixed concrete. emerged, dynamics in the This good work is always thwarted when the construction industry have been product is transported. At the point the load S changing quickly. Construction leaves the plant, all control and visibility is companies are beginning to prepare for lost. the ‘new normal’ and looking for solutions The problem is that once batched, concrete to accommodate new social distancing starts a complex chemical reaction known requirements. as ‘hydration’. It is a material that requires All stakeholders are obliged to rethink precise handling from batching to point how they provide their products and services, of delivery, but it rarely gets the positive while protecting their own staff, their attention it requires once it leaves the customers and the wider community. The production plant. This neglect during the digital transformation in construction is a delivery stage can result in concrete that is not prevailing theme, as all stakeholders come fit for purpose arriving at the job site and, in to grips with social distancing guidelines many cases, being poured. impacting the entire supply chain. To improve quality and reliability, the When it comes to concrete production, construction industry needs to be able to one of the biggest challenges lies in finding control concrete throughout the delivery new ways to maintain consistent concrete cycle using in-transit concrete management quality while observing social distancing and systems. GCP’s VERIFI system works by ensuring staff safety. By opening themselves installing Internet of Things (IoT) sensors up to innovation, concrete producers and on mixer trucks, enabling the producer project managers may discover solutions to monitor, measure, manage and record that not only address social-distancing multiple attributes of the concrete inside. requirements, but also improve efficiency and The result? Real-time management and sustainability in the longer term. control of the concrete slump, via addition of admixture and allowed water, and monitoring Rethinking processes of temperature during transport, delivering Concrete producers spend significant time improved concrete quality. and resources trying to reduce the variability The in-transit management system enables

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all interested parties to see what is happening where the truck is and the quality of the to the load after it leaves the plant. But, most concrete, which in turn can help improve job- importantly, it manages the load by keeping site planning. Today, the technology is being the concrete at the specified ‘slump’, so that it developed further to enable the control of is ready to pour upon arrival at the job site. other fresh concrete properties. By enabling tighter control over the On-site social distancing monitoring, measuring and managing Now, in the midst of the pandemic, the of construction project delivery, we can system is more useful than ever. By enabling optimise delivery processes, avoiding delays the automated adjustment of concrete in and improving efficiency. This in turn helps transit, the system ensures that when the reduce carbon emissions and saves time, concrete arrives on-site it is ready to pour, energy and money, revolutionising the way thereby reducing the need for manual testing the industry works. and site visits. The driver does not need to Perhaps now is the time for the concrete leave the truck, to add water, significantly industry to seize the opportunity to rethink reducing interactions on-site. Any on-site our ways of working and look at how we adjustments can be done from the cab and are can embrace innovation to help us face new automatically recorded. Subjective discussions challenges and at the same time improve our about concrete quality are removed, further processes and efficiency. reducing the need for close contact between people on-site. Tried and tested The Verifi system has already helped ready-mixed concrete producers deliver over When it comes to concrete 60 million m3 of quality concrete to “ construction sites across North America, production, one of the biggest Asia and in Europe. challenges lies in finding new ways to Colin Bamford, transport manager at maintain consistent concrete quality Extrudakerb, says, “With the system fitted to our truck mixers, we have been able to while observing social distancing and keep our supplies moving and still use social ensuring staff safety. distancing. Our drivers can add water from ” the safety of their cab without having to go to the back of the truck. This is ideal when Sophisticated internet-connected sensors we are delivering to our pavers on-site. The provide concrete producers and their pavers are on the motorways and space is of customers with real-time concrete data across the essence, so one less person near the paver their truck fleet, from plant to site. These and a busy highway keeps our driver safe and data are accessible on phones, tablets, laptops is social-distancing secure.” „ and desktops – anywhere there’s an internet connection. This means any issues spotted in transit can be addressed remotely, before arrival on-site, further reducing the need for plant and site visits for concrete testing or to resolve on-site problems. Social distancing in some form is here for the foreseeable future and it’s important to take all steps to protect employees, customers and the wider community. With this in-transit management system, the industry has an opportunity to embrace available technology in this area, technology that has wider benefits to the construction industry. The power of data analytics By providing this real-time data, aside from enabling compliance with social distancing requirements, Verifi technology offers a longer-term solution to increase productivity and facilitate quality assurance. It provides a contractor app with detailed truck and concrete data with real-time visibility of

www.concrete.org.uk JULY 2020 concrete 13 READY-MIXED CONCRETE Structural concrete in a zero-carbon future The next 30 years will see huge growth in the built environment, with an associated demand for structural concrete. At the same time, we need to reach carbon neutrality. How will we accommodate these seemingly irreconcilable futures? Paul Astle of Ramboll reports.

he United Nations (UN) has Embodied carbon predicted that, globally, we will contribution of typical 2 construct another 230 billion m structural concrete. T of floor area in the next 40 years, double the current floor area in the world’s buildings(1). In many situations, there is currently no practical alternative to concrete and it will play an important role in meeting this future demand. While concrete is a low-carbon material by weight, with only approximately 7% of the embodied carbon of steel(2), we use it in such vast quantities that our concrete carbon footprint is huge. A cubic metre of typical structural concrete has embodied carbon of

between 250 and 500kg eCO2. highlighted that structural elements are The recent article Specifying concrete for a typically only designed to use 60–80% of sustainable built environment(3) was right to their capacity – this is after all partial factors emphasise whole-life-cycle thinking when have been applied. There are also more assessing carbon during the design process. interesting opportunities that may allow a However, upfront embodied carbon, that renaissance in stunning concrete structures. which is associated with the material from By sculpting structural concrete we can its extraction to its placement in a completed cut out material and place as much of it is as building, needs to be tackled urgently. We possible in a compressive state. While these need a balanced approach, but we must ideas are not new, the design and construction recognise that it is the upfront carbon that challenges have limited their use. However, will have a disproportionate influence on we are now at a point in time when we can our ability to reduce carbon in the coming tackle these challenges with computational decades. power, advanced digital manufacturing and a To address the upfront carbon in concrete drive for low-carbon structures. Researchers we must focus on its constituents. at ETH Zurich have been working on how Portland cement is responsible for the to apply computational design to create greatest proportion of embodied carbon some compression-only concrete elements in concrete. For a pure CEM I concrete, it using innovative forming techniques to cut represents only 10–20% of the concrete by out unnecessary concrete. This can result weight, yet accounts for up to 90% of the in visually stunning, as well as materially embodied carbon (author’s calculations based efficient, structures. on ICE data). This is where we must focus We must also minimise the amount our attention if we are to continue using of cement in concrete. Frequently, more this important material in the future while cement is used than is needed to meet the meeting our targets. requirements. In a study (unpublished) by Reducing the amount of concrete used Ramboll of over 90 concrete mix certificates is an obvious first step and one we should used in UK projects, it was found that the already be acting on. Concrete is rarely used total quantity of cement (binder) in the to its full potential; in many applications concrete varied from 300 to 525kg/m3, even it is being used in a low-stress situation. for the same specified strength. There are, A University of Cambridge report(4) has of course, technical reasons for an increased

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cement content, but the range measured is far Additionally, geopolymer and alkali- in excess of the durability minimums set out activated technologies are gaining popularity in BS 8500-2(5). and there are efforts to formalise their use for technical structural applications. However, Carbon intensity these approaches are currently reliant on fly We also need to focus on the carbon intensity ash and GGBS, and are thus limited in the of cement. While Portland cement offers long term, without further development. fantastic performance, the direct process At present, simple steps can be taken to reduce unnecessary concrete, cement and emissions of CO2 from the calcination of limestone are responsible for 50–60% of carbon through optimised design, carbon- the associated carbon emissions. Even if we focused specifications and an increased use of assume that we can substitute the remaining SCMs. Longer term, we need to develop and thermal and operational energy required use new concrete technology with new mixes, with a carbon-neutral source, it would still designs and forms of construction. The be necessary to use costly carbon capture and carbon constraint will not stifle but catalyse storage technology to offset these process innovation and we may find that the solutions emissions. are far better than their carbon-intensive Increased use of supplementary predecessors. „ cementitious materials (SCMs) will play References: a key role in allowing us to reduce carbon 1. UN ENVIRONMENT PROGRAMME. Towards a zero- intensity while we develop other technologies emission, efficient, and resilient buildings and over the next 20–30 years. The two most construction sector. Global Status Report 2017. UNEP, common SCMs, GGBS and fly ash, are 2017, available at: www.worldgbc.org. co-products of steel blast-furnaces and 2. CIRCULAR ECOLOGY. Inventory of Carbon and Energy Database, v3 November 2019, available at: https://bit. coal-fired power stations respectively. The ly/2W9lBsL. life of these SCMs is thus limited by our 3. THOMPSON, G. Specifying concrete for a sustainable need to also address the carbon intensity built environment. Concrete, Vol.54, No.2, March 2020, of those industries. Nevertheless, we have pp.46–47. 4. UNIVERSITY OF CAMBRIDGE AND UNIVERSITY OF adequate supply currently and there is also BATH. Minimising Energy in Construction. Survey of work ongoing to access the many millions of Structural Engineering Practice. Report. MEICON, 2018, tonnes of landfilled fly ash. available at: https://www.meicon.net/survey2018. The potential for using calcined clays and 5. BRITISH STANDARDS INSTITUTION, BS 8500. Concrete. Complementary British Standard to BS EN 206. Part 2 – ground limestone filler is also considered to Specification for constituent materials and concrete. be a feasible and cost-effective approach in BSI, London, 2015+A2:2019. the mid-term. It has been shown that this 6. SCRIVENER, K.L., JOHN, V.M. and GARTNER, E.M. Eco- combination of SCMs can offset the use efficient cements: Potential economically viable solutions for a low-CO2 cement-based materials of up to 50% of Portland cement without a industry. Cement and Concrete Research, Vol.114, significant reduction in performance(6). December 2018, pp.2–26.

Unreinforced concrete funicular floor Variation in delivered concrete cement prototype (Block Research Group, ETH content on 90 projects. Zurich). (Photo: Nick Krouwel.)

www.concrete.org.uk JULY 2020 concrete 15 READY-MIXED CONCRETE

Concrete and contracts: design responsibility If concrete cracks, curls or spalls, and delamination or blistering occurs, the first question is usually ‘why?’. Often the answer is that one of three things is inadequate: the mix design, production or installation. Focusing on mix design, the second question is typically ‘who is responsible for that design?’. The answer is likely to depend on the terms of a contract between producer (seller) and purchaser. Lucinda Robinson and Jesse Way of Fenwick Elliott report.

oncrete producers do just that – produce concrete. On occasion the producer’s involvement in a project C is limited to supplying the concrete that is ordered and there is no practical involvement in the design of the mix (it is a ‘prescribed concrete’), or its selection for use. Other times, the producer supplies a concrete to meet the requirements of the purchaser’s specification (eg, ‘designated’ and ‘designed’ concrete) and will have determined the mix proportions and materials through extensive trials to achieve the desired properties. A producer, as part of its customer service, may also be asked to make recommendations for a particular mix design or materials to suit the concrete’s end use. Specific trials may also be undertaken. Importantly, the producer knows the end purpose of the concrete. While expertise and experience may equip a producer to suggest the right concrete for a particular use, it will not have all the information about the works that the structural engineer, architect or such consultants would have. Also, neither the producer’s profit margin on the concrete ‘satisfactory’ if they meet the standard that a supply nor its typical insurance policies will reasonable person would consider satisfactory, cover the fall-out from a catastrophic failure taking account of the description, price and in the design of the concrete structure. The other relevant circumstances. Quality relates producer is not best placed to take that risk to the state, condition, appearance, finish, or for ascertaining if the specification is durability and safety of the goods. Fitness appropriate for its intended purpose. But does for purpose is as one would expect – is the the law reflect the practical and commercial concrete fit for the purpose made known to position? the producer (whether expressly or impliedly and even if the purpose is unusual)? If the The general legal position producer did not know the purpose, or if the Unless there is a contract saying otherwise, purchaser selected the product without any the producer of concrete must supply advice or input from the producer, then the material that is of satisfactory quality and fit producer may have a defence. for purpose (because the Sale of Goods Act Setting this in context, if a purchaser 1979 sections 14(2)(a) and (b), and 14(3) requests a C16/20 strength-class concrete respectively say so). without telling the producer it plans to use it What does that mean? The goods will be in structural columns, then the fact it is not fit

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for purpose will be the purchaser’s fault, not sale of concrete is on its own T&Cs (how the producer’s. However, if the specification to do that is a topic in its own right). These for the strength or constituent proportions T&Cs should exclude design responsibility has not been met, the concrete will not be and the terms implied by the Sale of Goods of ‘satisfactory quality’ and that will be the Act, confirm that the goods are not supplied producer’s responsibility. for any particular purpose and limit the producer’s liability. At most, the producer Terms and conditions should commit only to producing concrete Purchaser’s T&Cs typically adopt and that meets the requirements of a specification strengthen the statutory position. It may drafted and owned by others. If the producer require the goods to be fit for ‘all’ purposes does not do this, then it will be taking on (known or not), demand the best – not just more responsibility than it probably intended. ‘satisfactory’ – quality and state that the producer accepts responsibility for design Proving fault (of both the mix and its choice for use in The terms of the contract are only part of the project) even when it is approved by the story. The cause of a defect must be the purchaser after a trial process. Not only established to determine if the problem will the producer be liable for defects in the really is the mix design, the specification or concrete as supplied or its specification, but something else. Proving that cause, whether also it will be easier to prove there was a it constitutes a breach of contract and any defect. Often purchasers will reinforce these loss that results, can be difficult. It will terms with an ‘indemnity’, increasing the involve factual and expert evidence, so it is amount that the producer will have to pay if vital that producers keep detailed records, the concrete is defective. eg, contractual documents, emails, the It is equally open to a producer to change specification, mix designs, batching records, the statutory position to its own advantage delivery tickets, test results and photographs. and avoid, or minimise, these risks. First, Together with its T&Cs, these records will it should ensure that any contract for the help protect the producer. „ WATER-RESISTANT CONSTRUCTION A systematic approach to designing a below-ground waterproofing solution With the high cost of land and the limited footprint of today’s construction sites in urban locations, the need to build structures with below-ground-level storeys is becoming ever more common. The chosen waterproofing system needs input from all parties to ensure that a robust and buildable solution is achieved, and it is vitally important that the design is undertaken systematically. Simon Morris of Fosroc International reports.

efined in BS 8102(1), Section 4 gases; and contaminants. The study should levels to change either temporarily or (Design Philosophy) states, “It also establish the likely highest level of the permanently as a result of the construction is essential for the success of any water table and the potential for a perched work, wider environmental changes or other D project involving below ground water table, and also to identify any missing developments during the lifespan of the structures that strategies for dealing with ground and groundwater information, which structure. groundwater, soil gases and contaminants should then be obtained by undertaking a site are considered from the very earliest stages investigation in accordance with BS 5930 and Internal usage of the planning and design processes. For BS EN 1997. The grades for internal usage as defined in new structures, it is recommended that the BS 8102 are: structural design, overall weatherproofing Risk assessment • Grade 1 – Some seepage and damp areas design, waterproofing design and A risk assessment should be carried out, that tolerable. Local drainage might be construction processes are considered considers the long-term water pressures, the necessary, such as car parking, plant together, as they generally interact. It is also effects of surface water infiltration and the rooms (excluding electrical equipment) recommended that, during the design process use of external drainage and cut-off walls. and workshops. and at all stages of the construction process, • Grade 2 – No water penetration the designers, specialists, manufacturers/ Water table classification acceptable. Damp areas tolerable; suppliers and installing contractors The grades for water table classification are: ventilation might be required, such as car establish good communication. Regular • High – where the water table or perched parks, plant rooms and workshops and clear communication coupled with water table is assessed to be permanently requiring a drier environment (than good site supervision allows variations and above the underside of the base slab. Grade 1) and storage areas. amendments to the design to be planned • Low – where the water table or perched • Grade 3 – No water penetration and executed without compromising the water table is assessed to be permanently acceptable. Ventilation, dehumidification performance of the waterproofed structure”. below the underside of the base slab. This or air conditioning necessary, appropriate These considerations can be broken down only applies to free draining strata. to the intended use, such as residential into the following categories: • Variable – where the water table and commercial areas, including offices, • site evaluation fluctuates. restaurants etc. • risk assessment • water table classification It should be noted that even when the site One area of debate is the expected • internal usage investigation indicates dry conditions, the risk standard for a car park in a new residential • types of waterproofing solutions of some waterlogging in the future should development. Today, we are seeing a • combined protection be assumed. It should also be noted that for requirement for a clean, well-lit, dry • accommodating the constraints of the site locations where either no geological or environment and therefore Grade 1 is no structure hydrological assessment has been undertaken, longer suitable. • remedial measures or the results of the soil investigations are • ground gases. inconclusive with respect to groundwater, Types of waterproofing solutions the water table classification should be Basement waterproofing solutions are Site evaluations assessed as high and it must be assumed that categorised in BS 8102 according to type: A desk study should be carried out in a head of water will come to bear against the • Type A – barrier protection. This is accordance with BS 5930(2) and below-ground structure. The assessment protection against water ingress, which is BS EN 1997(3) to assess the geology and should not just reflect the groundwater dependent on a separate barrier system hydrogeology, including: soil permeability; conditions found during a site investigation applied to the structure, usually in the flood risk; radon; methane and other ground but also the potential for groundwater form of a membrane. The membrane can

18 concrete www.concrete.org.uk JULY 2020 WATER-RESISTANT CONSTRUCTION

Type A waterproofing example. Type B waterproofing example. Type C waterproofing example.

be placed externally, sandwiched within unnecessarily expensive or compromised classification, as recommended in the construction, or internally. solutions could be the result. BS 8102. Ground gas protection solutions • Type B – structurally integral protection. should be based on an assessment of the This is protection against water ingress, Defects and remedial measures hazard potential and intended building usage, that is provided by the structure, usually Although an installed waterproofing system as recommended in BS 8485 for methane in the form of a concrete structure with would ideally be defect free, the possibility and carbon dioxide and in BR 211 for radon. good crack-width-control measures, that defects may be present should be The proposed solution should consider the incorporating waterstops in the joints recognised in the waterproofing design. intended construction method, external risk, and in many cases a waterproofing BS 8102 Section 4.3.2 states that two types required internal environment, feasibility admixture. Resistance to vapour ingress is of defect might occur so that the required of installation and other related issues, such dependent on sectional thickness. internal environment is not achieved in the as the need for combined protection and • Type C – drained protection. This is event of the structure being subjected to repairability of the installed solution. protection against water ingress into water pressure. These types of defect are BS 8102 Section 4.2 also advises “that a usable spaces, which is provided by the classified as: waterproofing specialist should be included as incorporation of an appropriate internal • defects owing to poor workmanship or part of the design team so that an integrated water management system. This is the inappropriate use of materials waterproofing solution is created”. An usually in the form of a cavity in the walls • defects owing to the specific properties of independent waterproofing design specialist and/or the floor through which water the materials being used. should not only have a suitable qualification ingress is channelled through to a such as the Certified Surveyor in Structural drainage system. It is essential that the waterproofing design Waterproofing (CSSW) but also be able to is such that ingress of water as a result of the demonstrate previous experience in providing Combined protection presence of either sort of defect is avoided, or a waterproofing solution for a project of a BS 8102 Section 6.2.2 recommends the potential for remedial work to be carried similar size, scope and complexity. that consideration should be given to a out following completion of the works is There is also a growing need to employ a combination of protective measures (ie, Type catered for in the design. specialist waterproofing designer carrying an A + Type B, Type A + Type C, Type B + appropriate level of design cover insurance, Type C) where in a single system: Ground gases highlighting a growing trend that design • the assessed risks are deemed to be high Consideration should also be given to the professionals, architects and structural • the consequence of failure to achieve the need to provide suitable protection against engineers are not willing to carry this aspect required internal environment is too high ingress from ground gases such as methane of design responsibility. This – alongside • additional vapour checks are necessary and carbon dioxide, in accordance with the the rapidly increasing cost of carrying the for a system where unacceptable water recommendations of BS 8485(4) and also to necessary level of insurance cover for typically vapour transmission can occur. protect against the migration of radon in 12 years following construction completion – accordance with BR 211(5). means that it’s as important as ever to ensure The use of a dual system should be based It should be noted that the protection score what you believe you are getting is actually on the assessment of the external risk and the should be achieved using at least two of the the case. „ required grade of the internal environment. following types of protection measure: • the structural barrier of the floor slab, or References: Accommodating constraints of the basement slab and walls if a 1. BRITISH STANDARDS INSTITUTION, BS 8102. Code of practice for protection of below ground structures Most structures will impose some form of basement is present (compliant with against water from the ground. BSI, London, 2009. constraint on the waterproofing design. Some BS 8485 Section 7.2.2) 2. BRITISH STANDARDS INSTITUTION, BS 5930. Code of common constraints include: the proximity • ventilation measures (compliant with practice for ground investigations. BSI, London, of adjacent buildings; infrastructure and BS 8485 Section 7.2.3) 2015+A1:2020. 3. BRITISH STANDARDS INSTITUTION, BS EN 1997-2. services; incorporation of an existing • gas-resistant membranes (compliant Eurocode 7. Geotechnical design. Ground investigation structure; whether a top-down or bottom-up with BS 8485 Section 7.2.4). and testing. BSI, London, 2007. construction method is used; the retaining 4. BRITISH STANDARDS INSTITUTION, BS 8485. Code of wall design; and whether movement joints Concluding remarks practice for the design of protective measures for methane and carbon dioxide ground gases for new are required. Waterproofing solutions for below-ground buildings. BSI, London, 2015+A1:2019. Unless the waterproofing design specialist structures should be based on an assessment 5. SCIVYER, C. Radon: Guidance on protective measures is involved at a sufficiently early stage, of the intended internal usage and water table for new buildings. BR 211, BRE, Watford, 2015.

www.concrete.org.uk JULY 2020 concrete 19 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:

SPECIAL CATEGORY MEMBERS

www.breedongroup.com www.laingorourke.com www.tarmac.com

www.cemex.co.uk www.sir-robert-mcalpine.com www.hanson.co.uk

The Society is supported by a global community of 250+ Corporate and 500 individual members. www.concrete.org.uk How can we use the indisputable laws of physics to our advantage? ‘Water always finds a way’ is a saying only too familiar within the construction sector, but we should always endeavour to use this to our advantage, according to Alex Burman of Sika. Here, he explains the cruciality of water-resistant construction and the considerations that should be made during specification and building.

very section of a structure that is infrastructure can, and will, change over the All photos: On-site 600mm or more below ground will lifetime of the structure and impact on the at the Keble College require some level of waterproofing water table and hydrostatic pressure below project. E to protect it from a current or ground. future ‘threat’ of water ingress. And with It can be all too easy to assume that waterproofing it’s important to start from the because there is no groundwater found at bottom up – figuratively and literally. the maximum depth of the structure, that There are many elements that dictate the the level of waterproofing protection can be waterproofing system(s) required as laid out reduced, saving money in the short term. But in BS 8102(1). These combine to give a level this can be a false economy, with repairs to of risk that needs to be mitigated with a range water ingress in subsequent years being many, of protective measures: many times the initial savings due to changes • Type A: barrier protection – typically outside one’s control. Therefore, many new- using a waterproofing membrane on the build insurance companies require more than outside of the structural concrete or a one measure of waterproofing protection for watertight render system on the inside. their cover to apply. Indeed, refurbishment • Type B: structurally integral protection – projects are starting to encompass the same by the use of a pore-blocking or rules as best practice. crystalline admixture in the structural concrete. The chain of command • Type C: drained cavity protection – an With this in mind, it is very important that internally applied system that directs any the correct experts are engaged early in a water ingress into a sump to be pumped project and with each interested party. away. The brief type, ie, whether design and build or just the former, will determine the In most cases, a combination of two of ‘chain of command’ and ascertain which these three protection systems needs to be party/parties have the authority regarding used to reduce the risk of water ingress, even specification. But, regardless of this, the key if the water table is below the lowest point to success is collaboration and making sure of the structure. This is because the ground the correct specialists are involved as early as conditions, environment and surrounding possible in a project.

www.concrete.org.uk JULY 2020 concrete 21 WATER-RESISTANT CONSTRUCTION

The waterproofing specialist should be agreement with the University of Oxford engaged in all stages of the supply chain, spanning 20 years, it was important for Laing which could comprise any or all of the O’Rourke to select the right partner for the following parties at any one time – client, project. client representative, main contractor, subcontractors, designer, consultant, Requirements engineer and suppliers. Depending on the Situated at the very centre of the campus, the type of project, the waterproofing specialist 13,411m2 scheme came with many logistical can develop and recommend different challenges: transporting plant machinery and waterproofing solutions, taking into materials; pedestrian access; noise restrictions; consideration complexity of use, product and ongoing clean-up requirements. guarantees, sustainability requirements and, The new biochemistry building needed of course, budget. Therefore, it is important to be linked to an existing building and to involve someone who has knowledge of, therefore tie into the previously installed and access to, a full range of solutions, not just system. The new basement, with a 2000m2 one they are pushing. footprint, required two types of protection What is also important to consider during to reduce the risk of water ingress: Sika specification is worst-case scenarios and how Watertight Concrete (Type B) and a Sika any issues should be dealt with if and when Cavity Drainage System (Type C). they arise. For example, specification of a With a requirement to waterproof the single supplier for all waterproofing material base slab and adjoining walls too, the whole solutions means one single port of call, project totalled 3800m2. systems that work together and a minimal number of contacts for any concerns or faults. Solution Sika worked closely with Laing O’Rourke Keble College on this complex project that required a raft With an acclaimed biochemistry building of technical support, to provide a holistic constructed in 2008, the University of Oxford concrete and waterproofing solution. appointed main contractor Laing O’Rourke Following the basement excavation and to build the £73 million phase two expansion installation of approximately 123 separate of the facility in March 2019. The institution 750mm-diameter piles, Watertight Concrete required extra space for the faculty and the was added on to the capping beam. This was new building would house very specialised seen as a far more robust and workable system equipment. With respect to a partnership due to the restrictions on-site with logistics and speed, and its proven track record. Sika’s Enduro Fibre HPP 50mm macro- synthetic fibres were specified for the screed, covering the Sika HD20 membrane on the slab, to provide a degree of crack control reinforcement. The watertight concrete system was completed using SikaSwell hydrophilic strips to seal the construction joints. Transportation and delivery of project materials was co-ordinated to minimise disruption on campus, where hundreds of people were present at all times of the day. Robert Dennis, UK business development manager at Sika, says, “The scheme at the heart of Oxford University saw us provide on-site support, technical drawings and bespoke fibre calculations in order to support Laing O’Rourke throughout the project. “While from the outset it could be perceived as a simple basement waterproofing project, when it’s situated at the epicentre of a bustling campus, the complexities were amplified.” „ Reference: 1. BRITISH STANDARDS INSTITUTION, BS 8102. Code of practice for protection of below ground structures against water from the ground. BSI, London, 2009.

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For further information on our webinars or product range contact: Fosroc International Limited Tel: 01827 262222 Email: [email protected] GLASS-FIBRE-REINFORCED CONCRETE Biophilic design: connecting GRC to nature

Concrete and nature? Not two words that many of us would instinctively use together. Urbanisation and migration into cities are likely to continue at a steady pace, increasing the requirement for more natural environments to be turned into urban conurbations and, for the foreseeable future, associated environmental issues will prevail. So, how can we escape this vicious cycle and how can the use of glass-fibre-reinforced concrete (GRC) become one way out of this situation? Bernhard Stömmer of Lindner Group explains.

s with traditional concrete, Biophilic design GRC is a durable building GRC’s logistical advantages and its use in product. Its application has many building in myriad forms and patterns in A uses, and – due to the use of an environmentally friendly way can help alkali-resistant glass fibres instead of steel in lowering the planet’s carbon footprint. reinforcement – it becomes a stronger, more But how can it actively contribute to durable material, able to produce thinner environmental protection and conservation? elements of the same strength, compared One key term is ‘biophilic design’. The key with normal steel-reinforced concrete. This idea of biophilic design concepts is to increase reduction of element thickness decreases the the connectivity of nature with building product’s weight and has a positive impact structures, and in particular to the people both financially and for the environment; it occupying them – ‘bringing some nature requires less space for container shipping, into our cities’, especially those that have and on-site handling is improved, as the eliminated almost all natural space. Used for use of heavy machinery can be widely single buildings or entire areas, this concept reduced or avoided. Additionally, for some can help by boosting staff mental health and applications, the element weight can be even enhancing morale and productivity. further reduced using lightweight GRC, GRC products are suitable to support such as Lindner’s LinCrete light, which is and realise such concepts in many ways; produced via spraying processes that saves on whether it is the realisation of organic shapes the consumption of resources such as cement, or elements inspired by nature, or a project water and energy. to build a new home for plants and wildlife.

24 concrete www.concrete.org.uk JULY 2020 Above and left: Samples showing the versatility of appearance and Logo made from LinCrete GRC. function of LinCrete GRC.

GRC elements can be used for artificial of these new technologies is the use of landscaping, for instance to form the basis of photocatalytic concrete. The key element indoor and outdoor waterfalls, or as a sturdy of this concrete type is the use of specifically base for building green spaces upon. Biophilic developed cement, such as TioCem by design and the practice of incorporating the HeidelbergCement that has TX Active natural world into the built environment is technology, which can be used with GRC not new to the world. products. This product has the ability to Features such as terraced-shaped buildings actively reduce the amount of air pollutants. and surrounding landscapes with planter The surface of such concrete types works with areas – sometimes combined in street titanium dioxide as a photocatalyst. Natural furniture concepts – have made their way daylight with UV radiance is sufficient to more and more into modern urban planning provoke this photocatalytic reaction on the and design in recent years. The advantage of surface of GRC elements. The results are widely customisable GRC products makes oxidising reagents that convert harmful NOx it possible to integrate them seamlessly into nitrogen oxides – caused by traffic and other all areas of design – from simple-shaped air polluting sectors, especially in cities – into – plant pots worked into a street furniture non-toxic harmless NO3 nitrates, which are concept, to complex organic structures and washed from the surface with the next rain patterns echoing popular natural elements shower. and matching the overall building design. Using TioCem cement with TX Active GRC can be the basis for balcony fronts and in the LinCrete ClAir products would mean façades that house plants, or for green roofs that 7140m² of active surface, equalling the that might additionally take the loads of size of an international soccer pitch, converts photovoltaic substructure systems for various the amount of harmful nitrogen oxides roof shapes. emitted by 100 VW Golf cars each with a The basic principles of Many GRC elements are available in range of 17,000km per year. photocatalytic concrete. a range of options regarding patterns and Further benefits of this technology surface treatment, no matter what the are the self-cleaning effect under natural requirements are – from sand-blasted, circumstances in cycles of sunshine and rain, acid-washed, or even porous – to ground or as well as the photocatalytic reaction being polished surfaces – and, furthermore, they are repeatable any number of times, as long available in various colours or with functional as the GRC element is in place, since the coatings for waterproofing, with anti-graffiti photocatalyst stays active even after several easy-to-clean surfaces and graphic methods cycles of biochemical reactions. for application on GRC elements. Using such products in GRC elements, especially with façades and noise barriers, Photocatalytic concrete photocatalytically active concrete surfaces are The concrete supply industry has developed created, which can make a major contribution special materials that can greatly contribute to keeping air clean in cities and on heavily to active environmental protection. One trafficked roads. „

www.concrete.org.uk JULY 2020 concrete 25 HISTORIC CONCRETE

The Isokon or Lawn Road Flats, Hampstead A Modern masterpiece The Isokon building of 1934, originally and more descriptively known as the Lawn Road Flats, is a landmark in the development of Modern Movement architecture in Britain and is now Grade I listed. It was progressive in its choice of reinforced concrete construction for high status dwellings, but rather more revolutionary in its design for encouraging communal living. In its construction and through the nature of its occupancy it was intended as a flagship of Modernism. Edwin Trout of The Concrete Society reports.

he decision to develop the plot the ‘Minimum Flat’ concept – first presented study engineering at East London College, on Lawn Road, Hampstead – an at the Congrès internationaux d’architecture gaining a PhD in 1924. Inspired in part established suburban road of moderne (CIAM) conference of 1929 – to by the example of his mother, who in her T elegant, but conventional houses – design flats with generous bed-sitting youth had been a pupil of Louis Sullivan, was made by Jack and Molly Pritchard who rooms and separate kitchens, bathrooms he developed an interest in architecture had bought the land in 1930. John Craven and dressing rooms. In all, there would be and planning, and after working briefly as a Pritchard was the sales and marketing 24 studio flats, eight one-bedroom flats and journalist at the Daily Express, secured a job manager of the Venesta Plywood Co, the staff quarters; the Pritchards would share a with the design firm of Adams & Thompson. British distributor for AM Luther, an penthouse flat. But unusually and indicative While there, Coates became attracted to internationally successful Estonian forestry of idealised modern living, there would be continental Modernism and influenced products firm. But with his wife and two a communal kitchen with a dumb waiter fellow architect Maxwell Fry (a colleague others he was also a director of Isokon and for delivery to flats, a shared garden to the and from 1930 a partner in the practice) in the Isokon Furniture Company, set up rear and a large garage. Furniture – made of its favour. in 1929 with the Canadian designer and plywood – was to be fitted throughout. He founded his own firm in 1928 and architect Wells Coates to design Modernist soon won commissions to design shop houses and the furniture with which to fit The architect fit-outs, offices for Cresta Silks in Welwyn them out. Initially called Wells Coates & Wells Coates (1895–1958), like the Garden City and – a formative experience Partners, the firm’s name was changed in Pritchards imbued with the new ideals of – the interiors of Broadcasting House in 1931; the choice of Isokon derived from Modernism, was pivotal to the enterprise. collaboration with the notable Modern Isometric Unit Construction – with echoes of Born in Japan to Canadian missionary architects Serge Chermayeff, Raymond Soviet Constructivism. parents, he had served in Britain as an RAF McGrath and the Twentieth Century Group. The new firm’s principal project was pilot during World War One. Subsequently Along with Chermayeff and Fry, he and to be the Lawn Road Flats and Molly graduating from the University of British Pritchard – with whom he was also by then commissioned Coates with a brief based on Columbia in 1922, he returned to Britain to in business – joined the Design & Industries

26 concrete www.concrete.org.uk JULY 2020 HISTORIC CONCRETE

Association, visited the Bauhaus and in 1933, floors. Helical Bar & Engineering Co was Notable residents having attended CIAM, founded its British commissioned to detail the reinforcement On 9 July 1934, the flats were formally branch, the MARS Group. and supply both the steel bars and clay opened for occupation. Intended as an ‘Helicon’ flooring units. architectural and social experiment in Design and construction Outer walls were composed of concrete modern urban living, they offered ‘Existenz As Coates’s career in these early years panels integrating with the floor and minimum’, with a communal kitchen and was accelerating towards Bauhaus- and reinforced to act as spandrel beams carrying laundry, bed-making and shoe-polishing CIAM-inspired Modernism, so his plans the edge of the slab. Dwarf parapet walls services provided centrally. Coates had for the Lawn Road Flats were developing on proscribed a flat roof and acted as spandrel absorbed Le Corbusier’s dictum, ‘machine à similar lines. Having decided on reinforced girders to carry the edge of the roof slab habiter’, and the Lawn Road Flats became, as concrete – the characteristically ‘Modern’ across the openings between adjacent since described, “an experiment in collective mode of construction – as providing the columns around the periphery. Window housing for left-wing intellectuals”. Indeed, it desired levels of insulation and fire protection, openings were fitted with the classic Crittal became quite a cosmopolitan community of he designed a streamlined four-storey steel frames. The exterior was then rendered artists, designers, writers and politicians, and block with a transverse structural frame and painted off-white (actually, a very pale a focus for the intellectual life of Hampstead and integrated external walls of concrete pink) to reflect the sun and reduce heat in the second half of the 1930s. Many had 4-inches (100mm) thick. The structure was adsorption. communist sympathies, some with Soviet designed in accordance with the London The control of interior temperature and connections, while others were refugees from County Council Building Regulations of noise – an inherent problem in flats, but Nazi Germany. 1915, in which concrete frames were treated accentuated by the contemporary adoption Famous residents included art historian as a translation of the steel frames otherwise of the wireless – was achieved by the use Adrian Stokes, writer Nicholas Monsarrat used for multi-storey buildings. It was an of insulating material, particularly sheets and photographer Edith Tudor-Hart (who approach superseded by Arup and Lubetkin’s of cork contained within the formwork for was both Bauhaus-educated and a Soviet 1935 design of the revolutionary Highpoint incorporation into the walls. Party walls spy). Distinguished archaeologists V Gordon Flats, a building project that integrated the consisted of two tied skins of ‘pumice’ Childe and Max Mallowan (with his rather frame with the structure. However, this later concrete blocks with a cavity between, while better-known wife, writer Agatha Christie) solution was only made possible by the DSIR internal partitions were made of Bricanion, a lived there too. Code of 1934 – not available to Coates – patented lathing, plastered to a thickness of Unsurprisingly, Modern architects were which permitted stresses 60% higher than 2-inches (50mm). attracted to the Isokon, including the those allowed by the LCC Regulations Although the Isokon Building is now continental émigrés Jacques Groag, Arthur and, by reducing the quantity of expensive identified by its distinctive ‘ocean liner’- Korn and Egon Riss. But perhaps most steel required, caused reinforced concrete to inspired external stairs and walkways, the conspicuous were the Bauhaus teachers, became much more economical. principal access has always been by an Walter Gropius (with his wife Ise), Marcel The superstructure was founded on enclosed staircase. The external stairs and Breuer and Laszlo Maholy-Nagy (with his isolated tapering pads, with columns front balconies were, however, initially lit at night wife Sibyl). All three became involved with and back at 3.2m intervals. These supported to promote the building’s propaganda role for the Isokon Furniture Company: Gropius, single-span T-beams carrying hollow-pot Modern architecture. then Breuer in his turn, as controller of

All photos: The Grade I listed Lawn Road Flats today, showing the pale pink colour and ‘ocean liner’-inspired external stairs and walkways.

www.concrete.org.uk JULY 2020 concrete 27 HISTORIC CONCRETE

“Famous residents included art historian Adrian Stokes, writer Nicholas Monsarrat and photographer Edith Tudor-Hart (who was both Bauhaus-educated and a Soviet spy). Distinguished archaeologists V Gordon Childe and Max Mallowan (with his rather better known wife, writer Agatha Christie) lived there too.”

design and Moholy-Nagy as designer of flats remaining popular in the Blitz for their Conisbee & Associates the consulting the company’s branding and promotional sturdy concrete construction – his children engineer. material. Also resident was the Russian were sent to Canada and Molly to stay with The building was by then in a poor state goldsmith Naum Slutzky, who had taught at Walter and Ise Gropius in Massachusetts. of repair and experiencing a tilt of 150mm the Bauhaus in Weimar. The building was painted brown to avoid towards Lawn Road due to differential Indicating possibly that the ideals of it being used as a landmark for German foundation stresses, exacerbated by seasonal communal living were proving difficult to bombers and survived several nearby bomb movement from nearby trees. But despite sustain in practice, the shared kitchen was blasts. However, after the war, tastes had moisture ingress (resulting from failed roof superseded in 1937 by a restaurant and bar, changed and in 1946 the Isokon came second coverings), corroded reinforcement and some the fashionable ‘Isobar’ designed by Breuer in Horizon Magazine’s ‘Ugliest Building’ surface spalling, the reinforced concrete fabric and FRS Yorke. Regulars included the locally competition. was basically sound and capable of repair by based artists and sculptors Henry Moore, The building was increasingly bypassed traditional means. Barbara Hepworth and Ben Nicholson, and and although some notables such as the Makers UK was taken on as the concrete Sir Julian Huxley, secretary of the Zoological architect Sir James Stirling lived there in repair contractor and in 2003–2004 the Society of London. the 1960s, Pritchard (having revived the necessary work was undertaken; with the Isokon Furniture Co in 1963) sold it to the repairs followed by attention to insulation, 1934–1939 New Statesman in 1969. The new owner building services and interior decoration. Wells Coates’s other architectural success converted the Isobar into flats and in 1972 Eventually, the restored render was tinted of 1934 was the archetypically Modernist sold the building to Camden Council at twice pale pink as it originally had been and a ‘Sunspan’ house design, developed for the the purchase price. Though listed Grade II gallery installed in the former garage. Daily Mail Ideal Home Exhibition with his in 1974, it was used by the council to house Later in 2004, it won a certificate of by then partner David Pleydell-Bouverie. single men with drug, alcohol and mental excellence in the Mature Structures category As for flats, he followed Lawn Road with health problems. By the 1990s it had been at The Concrete Society Awards, the judges two more experimental apartment buildings: abandoned and was in a derelict condition. declaring, “This is a classic Modernist design, Embassy Court, Brighton (1935) and 10 well restored but retaining enough of its Palace Gardens, Kensington (1939). His Refurbishment original construction and is an architectural assistants throughout this period were Eventually, as its architectural importance icon we all should recognise.” the young architects Patrick Gwynne and became more widely appreciated, the Isokon’s Denys Lasdun – the latter known for his listing was raised to Grade I. Camden Bauhaus commemorated post-war Brutalism in such structures as the Council decided to dispose of the property The refurbishment was a commercial success, Southbank Centre. and in 2000 the Notting Hill Housing Group with potential purchasers queuing for the won the council’s competition to acquire, flats the day they went on sale. And today the Post-war decline conserve and renovate the block, offering to flats’ former residents are not forgotten either: The outbreak of war brought an end to provide 25 key-worker studio apartments a blue plaque added in 2018 commemorates the Lawn Road Flats’ heyday. The Isokon and ten one-bedroom flats for open sale. The the Bauhaus triumvirate of Gropius, Breuer company folded when plywood supplies were Pritchards’ penthouse apartment would be and Moholy-Nagy – an enduring reminder cut by the Soviet invasion of Estonia and retained. Avanti Architects was appointed of the cosmopolitan Isokon’s continental though Pritchard stayed on in London – the to oversee the refurbishment, with Alan connections. „

28 concrete www.concrete.org.uk JULY 2020 
 
 

 
  
 
 
  

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J *5!7A05A75=AA=*5*5#7=#D,J  JJ J GGGJA05A75=AA=*J5J*5#7=#D,J Telegraph Hotel set to become icon of Coventry’s cityscape

The former home of the Coventry Evening Telegraph is set to be transformed into a design- led four-star hotel, with 88 bedrooms, meeting and conference facilities, a rooftop bar, restaurant and duplex penthouse suites. The completed hotel will feature many of the original aspects of the 1950s architecture of the original building. Sophie Davies reports.

etween 1957 and 1958, a building One of the city’s most iconic buildings, Artist's illustration of was constructed on the corner of it was at the heart of a city redeveloped finished project. Corporation Street in Coventry by the innovative city architect and town (Illustration: Hadfield Cawkwell B city centre to house local newspaper planner Sir Donald Gibson, who favoured Davidson.) the Coventry Evening Telegraph. The the ‘polycentric’ planning of cities which paper, which was originally founded as The are planned without a central hub. The Midlands Daily Telegraph in 1891 by Lord modernisation of Coventry city centre began William Isaac Iliffe, was Coventry’s first daily prior to the destruction of the city during newspaper and was sold for half a penny. the Blitz, which was responsible for the only The building comprises two four-storey day the paper was unable to publish – 15 blocks, facing onto the primary street November 1940 – following the famous frontages on the corner of Corporation bombing of the city by Nazi Germany Street and Upper Well Street, with a lower during World War Two. As the home of the L-shaped block to the rear forming an British car industry, the city was already on internal courtyard. its way to being modernised by Gibson, with Corporation Street being created in 1931 as part of the redevelopment. The foundation stone for the Telegraph building and the new headquarters was laid by the then proprietor, Lord Iliffe gbe, on 21 November 1957. The Iliffe family owned the newspaper for 96 years; the current Lord Iliffe will visit the new development ahead of the hotel opening. Until centralisation of printing for the region in 2010, the headquarters of the newspaper was at 157 Corporation Street, which housed the offices and print works, purpose-built within the basement. Basement The basement contained the lowest part of the triple-height machine room, as well as paper storage areas, the ink store and storage for the large reels of paper that used to run through the presses. This was extended with the construction of a new print hall in Compositing room on the first floor (later the computer server room).

30 concrete www.concrete.org.uk JULY 2020 HISTORIC CONCRETE

1990. The basement was constructed with with a long hardwood reception desk an in-situ concrete slab, combined with spanning the entire length of the space. concrete bases for the printing presses – The floor is covered in terrazzo, laid in a the building was designed for two presses, green and off-white chequer-board design, although initially only one was installed. with columns clad in marble with brass and The basement retaining walls were also of hardwood detailing; features that will be concrete construction, 12-inches (305mm) retained in the new hotel. The four-storey thick with asphalt tanking and 4.5-inch blocks facing onto Corporation Street and (115mm) brickwork on the exterior face. Upper Well Street are brick and stone clad, The printing press was centred in the and contained the public reception area basement, as the heart of the building and and office accommodation, while the rear the newspaper, but the main entrance to the elevations have brick façades set within building was on the corner of Corporation an exposed concrete frame. This exposed Street, to give a good first impression for concrete is a prominent feature of the two- visitors and staff. Externally, a large concrete storey section on Upper Well Street facing canopy with a circular roof light covered the the Belgrade Theatre. entrance area, which had a mixture of paving, cobbles and a large sculpture. The walls of Prime position this area are clad in marble and contain the In prime position overlooking the theatre inscribed foundation stone, and a set of three was Lord Iliffe’s personal office and flat, frameless glass swing doors with engraved the boardroom and director’s dining brass and hardwood push-plates lead via a room. The dining room is fully panelled small lobby into the public reception area. on all walls and had the same high coved Occupying the whole ground floor of the ceiling as the adjacent boardroom, with the block, the large and opulent reception space panels containing concealed hidden drinks provided the public face of the newspaper, cupboards and a door leading to Lord Iliffe’s

Reception area (note: terrazzo flooring, marble columns and reception desk remain until present day). HISTORIC CONCRETE

Above: Entrance.

private quarters. The Lord Iliffe Suite, set in his former flat, will be the most impressive in the new hotel, featuring three rooms, two bathrooms and a private terrace with hot tub. In the summer of 2012, the paper moved its headquarters to Thomas Yeoman House at Coventry Canal Basin, in Leicester Row. The decision by the proprietors was a consequence of the changing patterns of work at the paper, and the industry in general. The new Telegraph Hotel, which is set to open in October this year, is being developed by Complex Development Projects (CDP) and will be operated by Bespoke Hotels. „ Compositing room on the first floor.

Main entrance on Corporation Street. Construction Information Service Supporting every stage in the construction life-cycle

An online tool to quickly access current regulations, construction standards, technical advice and industry news on building, engineering, design and construction processes in the United Kingdom and Republic of Ireland. Updated weekly, the CIS offers a powerful search engine to find authoritative information for every stage of the construction lifecyle from design and completion to operation and ongoing use. Easy-to-use search filters allow you to query 26,000+ documents – including full text copies of British standards, CIBSE documents, and technical data from 500+ publishers.

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CUSTOMER CARE EUROPE, CUSTOMER CARE AMERICAS CUSTOMER CARE ASIA PACIFIC MIDDLE EAST, AFRICA T +1 800 447 2273 T +604 291 3600 T +44 1344 328 300 +1 303 858 6187 (Outside US/Canada) E [email protected] ARCHITECTURE AND DESIGN

Barrow House, Lincolnshire The East Midlands’ only Area of Outstanding Natural Beauty, the Lincolnshire Wolds, has some of the region’s most beautiful scenery, with rolling hills, hidden valleys and quaint villages. Now, this rural haven also boasts Barrow House, winner of the 2019 Local Authority Building Control (LABC) ‘Best Individual New Home’ and shortlisted for the RIBA Yorkshire awards 2020. Concrete report.

esigned by ID Architects and built is one of the reasons why it was chosen as by Belvin Construction, Barrow LABC’s Best Individual New Home of 2019. House is a bespoke, contemporary D home made largely from Corten Foundations steel and concrete. Designed to resemble Work began on Barrow House in October a traditional barn when viewed from the 2017. The building sits on previously farmed top of the valley, the single-storey Corten arable land and required the installation of 99 ‘barn’ stands above a concrete structure concrete piles and ring beam to ensure that it that contains the main living areas. With was founded to good bearing ground. a concrete hardstanding and with concrete being used extensively inside and out, Barrow Exterior House demonstrates the versatility and luxury Once the foundations were complete, the of the material. process of creating the formwork for the concrete retaining walls began. These were Rural areas created with steel forms that fitted engineers’ Barrow House is the first home in specification; a time-consuming task but vital Lincolnshire to be brought forward under in getting the structure of the house correct Paragraph 79 of the 2018 National Planning and up to standard. Policy Framework, relating to building new Formwork then began on the concrete From the roadside, Barrow House isolated homes in the open countryside. bulkhead front section and the chimney, resembles a modest, pitched-roof pantile This is a clause that limits the construction which was carried through until the farm building, similar to other barns of isolated new homes in rural areas to those completion of the external walls. Once the across Lincolnshire. that are of outstanding and innovative design. concrete retaining walls were complete, the Designed with this in mind, Barrow House structural steelwork was then installed which required extensive consultation and liaison provides the structure of the cantilevered with planners, the local community and other ‘television box’, which the client’s main stakeholders before it could be approved. bedroom occupies. The ‘barn’ was also built The concrete structure is nestled into at this stage – time was taken to measure the hillside, so the main living areas are each Corten panel individually before subterranean. As a result, the house is a being installed with cranes to complete the masterpiece of camouflage; it could easily precision-cut barn roof and cladding. be mistaken for one of the pitched-roof Concealing the flat roof of the subterranean farm buildings that are scattered across concrete box, which forms the main structure the Lincolnshire landscape, rather than a of the building, is a wildflower meadow. In dwelling. However, as one walks around it, order to make the meadow vision a reality, Barrow House reveals a stunning structure a single-ply roof was installed, inclusive that seems to defy gravity, while being at one of parapets, to create a roof area, which is with the landscape. This stunning design consistent with the surrounding landscape.

34 concrete www.concrete.org.uk JULY 2020 A concrete fireplace divides the space to create a cosy sitting room.

The concrete lower level is contrasted by the black steel panels that clad the Viewed from the valley, the The master bedroom appears to float overhanging master bedroom. subterranean level of Barrow above the landscape, overlooking the House is revealed. valley below.

Interior are also cast in concrete, being left exposed Once the external walls were in place, it was and polished to create a light and airy living necessary to prepare for the installation of the environment. first-floor interior space. Blockwork began to create the inner leaf walls and roof joists Completion and trusses were also installed, with roofing Once the final finishing touches, such as membrane and battens, in preparation for tiling, interior decorations and flooring, cladding materials. Once the interior walls were added, the build was finalised and is were built, the hollowcore concrete planks now fulfilling its purpose as a much-loved could be installed to create the upstairs floor family home. Approximately 250m3 of space. concrete went into the creation of this Offering a faster and safer installation than magnificent structure, proving once again in-situ concrete, hollowcore concrete was that concrete can be used to create a modern also a more sustainable option, due to the and comfortable living environment, that reduced quantity of concrete needed to create perfectly complements the natural landscape the planks. The kitchen island and hearth in which it sits. „

www.concrete.org.uk JULY 2020 concrete 35 ARCHITECTURE AND DESIGN

Grey supporting green

Exploring the important role that concrete plays in supporting green infrastructure in the UK and its strong biodiversity credentials. Elaine Toogood of The Concrete Centre reports.

he recent Covid-19 lockdown take accommodation, transport routes and has highlighted to the nation the other essential infrastructure below ground, value of green space and access necessary for freeing up space to create and T to nature from our homes and connect parks and green spaces. workplaces. Furthermore, greening the urban For buildings and structures of all types, environment has been shown to reduce heat concrete’s inherent stability, robustness and island effects and the risk of overheating, resilience to water makes it ideal to support as well as improving flood resilience and all kinds of green walls, and blue/green encouraging biodiversity. With biodiversity and green roofs. These solutions not only net gain embedded in planning policy, cool the environment and improve flood the use of urban greening factors widely resilience by slowing the path of rainwater encouraged and nature-based solutions being into the drainage system but also have been integral to the UK Green Building Council’s shown to improve the efficiency of roof-top ambition for all buildings and infrastructure photovoltaic panels. by 2030, the focus on green infrastructure looks set to increase. Roof gardens So, what is concrete’s role in nature-based According to the Green Roof Code of Best solutions, when common parlance seems to Practice for the UK(2), where a flat roof is to place the material as its antithesis? ‘Designed act as a roof terrace or roof garden (ie, an to bring more nature and natural features intensive green roof ), they should only be and processes to cities, landscapes and used in conjunction with concrete decks. seascapes’(1), the initiatives are principally In other words, concrete is essential for the related to landscape and urban design, creation of accessible roof gardens to provide concerned with naturalising our external the associated amenity, and physical access spaces and features, and sequestering carbon to plants and fresh air. A Berkeley Homes through a growing landscape, eg, trees in development – Goodman’s Fields in central parks, soil in the ground and plants on roofs. London – was designed with both people It is not directly concerned with the structure and wildlife in mind. The end result, which of buildings. relied heavily on its concrete frame, is that Facilitating the shift away from impervious the project has been cited as a green roof and horizontal, hard surfaces with an aim of biodiversity exemplar. reducing rapid rain run-off are a range of A common thread in nature-based design established, effective and attractive concrete is the approach to water: opening up access permeable paving solutions used for to this natural resource and replacing hard sustainable urban drainage systems. They, barriers in favour of ‘softer’ edges, such as together with other locally and responsibly beaches, or floodable green spaces. Many sourced concrete landscaping products (such existing hard coastal and flood defences are as planters and raised beds etc), provide constructed using concrete, but there are plenty of opportunity for water storage and opportunities for approaches using concrete for planting. More fundamental, however, is that deliver protection and benefit marine the unique ability of concrete structures to and coastal biodiversity. It is interesting to

36 concrete www.concrete.org.uk JULY 2020 ARCHITECTURE AND DESIGN

note the considerable research and trials hectares are committed to in restoration in this field of work, such as Bioblocks in plans. So, the industry has a long track-record Plymouth Harbour and Ecostructure off the of delivering biodiversity net gain and will coasts of Ireland and Wales, where casting continue to lead the way in the future. Broom texture and relief in the surface of concrete Quarry, Bedfordshire, a former sand and has been shown to encourage plant growth, gravel quarry, has been restored to a mixture with different textures encouraging different of wildflower meadows, wetlands, woodland species. Further afield, the provision of and farmland, a massive transformation on concrete reefs in the Maldives, Malaysia and what was originally uninteresting, agricultural elsewhere has successfully helped preserve land. The result is of great value to both large stretches of threatened coast line, the community and wildlife, and represents themselves colonised with wildlife. just one of over 70 sites available for public enjoyment around the country located in Biodiversity restored quarries. Innovation in the use of concrete to support biodiversity has also led to the creation of concrete bat boxes, bee blocks and the like, “The provision of concrete reefs in designed to be freestanding or incorporated the Maldives, Malaysia and elsewhere into buildings. One project in Belgium used has successfully helped preserve large rammed concrete façades then incorporated holes specifically to provide homes for stretches of threatened coast-line, masonry bees. Researchers have developed themselves colonised with wildlife. ‘bioactive’ or ‘bioreceptive’ concrete wall ” panels that support vegetation using surface texture and a porous matrix to retain So, concrete-based construction in the moisture. UK has the potential to continue to support But in the UK, concrete’s support of and enhance biodiversity and nature in biodiversity and natural habitat does not rural, urban, terrestrial and marine settings, need to solely rely on innovation, or even and remains an essential part of our built new legislation; it is already intrinsic to the environment; an environment that looks set making of the material. Approximately 95% to be green rather than grey. „ of the concrete used in UK construction is manufactured in the UK, using locally References: sourced materials, primarily aggregates (rock, 1. EUROPEAN COMMISSION. Nature-based solutions. sand and gravel). Through the restoration Available at: https://ec.europa.eu/research/ and management of the quarries in the UK, environment/index.cfm?pg=nbs, accessed June 2020. 2. GREEN ROOF ORGANISATION. The GRO Green Roof at least 8000 hectares of priority habitats have Code. Green Roof Code of Best Practice for the UK. been created and at least an additional 11,000 Groundwork Sheffield, Sheffield, 2014.

All photos: Broom Quarry, Bedfordshire. (Photos: Tarmac.)

www.concrete.org.uk JULY 2020 concrete 37 LOW-CARBON CONSTRUCTION Low-carbon cement opportunities

With commitments from the cement and construction industries to reduce their future carbon footprints dramatically, the focus sharpens on how this can be achieved. Nina Cardinal of Hanson Cement reviews existing choices and future developments for low-carbon cement options.

key focus of the cement industry has been the use of alternative fuels to fire the kilns for the A production of clinker, the main constituent of Portland cement (PC). In the UK, the use of refuse-derived fuels, other wastes such as solvents, old tyres and bone meal, and biofuels contributed 43% of the thermal input to the cement manufacture process in 2019 according to the Mineral Products Association (MPA)(1). The cement industry consumes many times more waste than it generates, which often includes those wastes that are difficult to dispose of otherwise. In addition to using fuels with a lower carbon footprint, the industry also constantly searches for opportunities from industrial by-products with raw material potential for clinker production, which, again, would otherwise go to landfill. Their mineral content contributes to the final clinker Accelerated carbonation product and they have made up almost 10% test results. of cement(1). These efforts drastically reduce the overall environmental impact of cement production. With respect to greenhouse gas emissions, Again, by-products from other industries, go to landfill, these SCMs have a much lower an increasing number of companies make in particular GGBS from the steel industry carbon footprint than PC. binding commitments via the Science Based and fly ash from the power generation However, fly ash is already in short supply, Targets Initiative (SBTi)(2). Hanson’s parent industry, come into play. This has been with all coal-fired power stations in the company HeidelbergCement Group, for common practice for almost a century UK being phased out by 2025 at the latest. example, has committed under this initiative with the first British Standard for Portland Current efforts concentrate on securing to reduce its Scope 1 (direct emissions from Blastfurnace Cement having been published and developing reclaiming processes for owned or controlled sources) and Scope 2 in 1923(3). the 100+ million tonnes of fly ash currently (indirect emissions from purchased energy) For most of the 20th and early 21st estimated to be stockpiled at power stations by 15% and 65% per tonne of cementitious Centuries, the drivers for using GGBS and sites (according to the UK Quality Ash material respectively, between 2016 and 2030. fly ash in combination with PC have been Association). And the UK cement industry as a whole is initially economic, and then also technical, Similarly, the UK already relies on committed to reducing CO2 levels by 81% by advantages such as providing increased imports of granulated blast-furnace slags 2050 from 1990 levels. resistance to sulfate attack, reducing the risk to produce the amount of GGBS currently of alkali–silica reaction and limiting the heat required. With the world's steel industry Supplementary cementitious of hydration of mass concrete pours. switching increasingly to electric arc steel- A parallel effort to reduce the carbon In the past decade, the focus has turned making, GGBS is likely to become a scarce footprint of cement lies in the use of to the carbon-saving element of the use of commodity in the coming decades. supplementary cementitious materials GGBS and fly ash. As by-products of other Due to the already real, and future (SCMs). industrial processes, which would otherwise potential, supply limitations associated

38 concrete www.concrete.org.uk JULY 2020 LOW-CARBON CONSTRUCTION

with GGBS and fly ash, limestone fines are Individual silos for CEM I and GGBS or fly through this programme, it is the intention gaining increased attention and interest. ash are common practice, as are replacement to apply for inclusion of these cements in While cements with limestone additions of levels of up to 70% and 30% respectively. BS 8500 for more aggressive environmental up to 20% are common in the UK packed By combining GGBS and fly ash with exposures. products market, they are less common in limestone cements, in effect producing An example of promising accelerated ready-mixed concrete applications than in composite cements, further carbon-saving carbonation test results for a group of CEM continental Europe. A market shift towards gains can be made. However, this is where II/B-M and CEM VI cements with GGBS the use of limestone-blended cement is both the cement Standard EN 197-1 and levels up to 55% and limestone levels up to required in the UK to tap into this significant the British Standard for concrete BS 8500(6), 15% is shown in Figure 1. opportunity for lower-carbon cement. which supplements the European Standard There are, of course, also continued efforts for concrete, EN 206(7), limits developments in the development of reduced clinker or Standards and opportunities within their current framework: even clinker-free alternatives to Portland All cements commonly used in the UK and • EN 197 does not cater for combined composite cements, with alkali-activated the rest of Europe are standardised in EN levels of GGBS, fly ash and limestone geopolymers, metakaolin and the use of steel- 197-1(4) and there is ample scope within higher than 35%, eg, if 15% limestone making slags attracting significant research this Standard to adopt low-carbon cement was blended into the cement, the and commercial interests. practices. Cements in this Standard come in maximum possible GGBS or fly ash Other developments to reduce the five groups as follows: addition would be 20%, well below the embodied carbon emissions associated with 1. CEM I – Portland cement (PC) levels currently used with CEM I. clinker production, the main constituent of 2. CEM II – they fall in two groups as • BS 8500 (Table A.12 in Part 1 of the CEM I, will continue and even intensify. An follows: Standard) does not allow the use of example in this area is the recently announced - PC clinker with individual additions composite cements containing limestone award by the BEIS of an MPA-led project of up to 35% of SCMs, such as in more aggressive environmental demonstrating the potential of hydrogen and GGBS, fly ash, silica fume, conditions; for example where DC-3 and plasma technology for cement kilns. pozzolanas, burnt shale and limestone DC-4 apply. Even if the fuels used to heat the cement - composite cements that cater for a kilns eventually become carbon neutral, blend of SCMs with PCs where the Where next? the chemical laws of clinker production sum of SCM additions must not The limitations in EN 197-1 with regards dictate that this process will always be

exceed 35% to composite cements are being addressed at associated with the release of CO2 through

3. CEM III – blast-furnace cement with European level and an extension to its scope the calcination of limestone: CaCO3 + heat =

GGBS additions of up to 95% has been proposed for some time. It will CaO + CO2. The cement industry is heavily 4. CEM IV – pozzolanic cement with fly cater for composite cements with combined involved in the exploration of carbon capture ash and pozzolana additions of up to replacements levels up to 50% – up 15% and storage solutions in order to mitigate

64% from the current 35% maximum. They are the CO2 emissions of this process. Examples 5. CEM V – composite cements with a to be named CEM II/C-M. It will also include potential demonstration plants by minimum PC clinker content of 20% introduce a new class of GGBS composite HeidelbergCement in Norway and Canada, and a combination of GGBS and cements, CEM VI, with GGBS levels up and by Holcim in Colorado, USA, as well pozzolana and fly ash additions of up to to 60% and other SCMs, including natural as the European-funded LEILAC project 50% each. pozzolanas, fly ash and limestone, up to supported by HeidelbergCement, CEMEX 20%. However, due to a legal deadlock at the and Tarmac. „ Groups two to five all represent lower- European Commission level, progress of this References: carbon options compared with PC (CEM I). development has been stalled. An alternative CEM IIs with limestone contents up to approach in the form of a non-harmonised 1. MPA CEMENT. Sustainable Development Report 2019. Mineral Products Association, London, 2019. 20% (ie, CEM II/A-L or CEM II/A-LL) Standard is now being pursued to realise the 2. SCIENCE BASED TARGETS. Available at: https:// are already used widely in the UK in packed carbon-reduction benefits that these new sciencebasedtargets.org/, accessed 26 February 2020. products. Carbon emissions associated cements offer. 3. CLEAR, C. UK Procedures for the Use of Additions as with CEM II limestone cements are The limitations with regards to BS 8500 Part of Cement in Concrete. Proceedings of the XVII ERMCO Congress, Istanbul, Turkey, 2015, available at: approximately 20% lower than those of CEM are being addressed through an extensive www.brmca.org.uk/downloads. I cement. Equally, CEM IIIs with 50% or testing programme of ternary composite 4. BRITISH STANDARDS INSTITUTION, BS EN 197-1. Cement. Part 1 – Composition, specifications and 70% levels of GGBS give a CO2 reduction cements containing GGBS and limestone of 45% and 63% respectively, as shown by or fly ash and limestone, in DC-2 and DC-4 conformity criteria for common cements. BSI, London, (5) 2011. MPA . environments. This collaborative programme 5. MINERAL PRODUCTS ASSOCIATION, Fact Sheet 18.

The biggest immediate opportunity to is part-funded by the Government under Embodied CO2e of UK Cement, additions and reduce the carbon footprint of cement and the Department for Business, Energy and cementitious materials. Rev.4, MPA, London, available concrete in the UK further is through the Industrial Strategy (BEIS) Industrial Energy at: https://cement.mineralproducts.org/documents/ Factsheet_18.pdf , accessed 5 March 2020. ready-mixed concrete industry adopting, in Efficiency Accelerator programme, managed 6. BRITISH STANDARDS INSTITUTION, BS 8500-1. addition to the existing GGBS practices, by the Carbon Trust and Jacobs, and led by Concrete – Complementary British Standard to BS EN CEM II/A-L or A-LL more widely in its MPA, with input from Portland cement and 206. Part 1 – Method of specifying and guidance for the mixes. In many cases, companies already SCM manufacturers, and executed by BRE. specifier, BSI, London, 2015+A2:2019. 7. BRITISH STANDARDS INSTITUTION, BS EN 206. operate a low-carbon approach through If the suitability of composite cements in Concrete – Specification, performance, production and their blending practice at batching plants. chemical classes DC-2 to DC-4 is proven conformity, BSI, London, 2013+A1:2016.

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