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a little book ofConcreteWhy precast concrete?A guide to onehundred advantages

If concretewere to beinventednow itwould behailed asa miracle.It is the most commonly used building material in theworld; yet we normally take what it does for granted – toooften this means that much of what concrete can offer isoverlooked.Now it is time to take a fresh look at the new world ofconcrete.This booklet re-examines what factory-made precastconcrete can offer the architect, the designer, the engineer,the client, the financier, the insurer and the environmentalist.Precast concrete covers all factory-made concreteproducts from mass produced blocks, paving and roof tiles,to massive customised bespoke units.We hope you enjoy reading about the 100 advantages ofprecast.If you wish to know more contact:

Contents5. Precast – fit for purpose23. Structures for today and tomorrow43. Amazing architecture and finishes63. Quality production and construction83. Protecting people and the environment103. The best value solutionPrecast fitfor purpose

Withstandseveryday use.All structures and buildings are subject to everyday wearand tear and this is where the use of precast concretereally makes sense. Its hard, tough surface is extremelyresistant to everyday dents and punctures.Weather-proof.Precast concrete is resistant to rain penetration andwind-blown debris. It can also withstand many wintersof freeze-thaw cycles, unlike other materials whichcan deteriorate quickly with such regular exposure toexpansion and cracking.

Quiet...As a dense material, precast elements in a buildingmake for a peaceful lifestyle. Privacy and effectivesound reduction are ensured, which makes precastand masonry an ideal choice for residential buildings inparticular.…yet acousticallyversatile.Because precast can be moulded to any shape, sizeand texture it can be used to deflect or absorb noise.This makes it a good acoustic host for music but alsoan effective sound barrier alongside busy roads.

Keeps water in…Precast is an excellent material for containment,whether this is for mains storage or domesticrainwater collection. The strength and resilienceof precast has been proven for these and otherapplications such as wastewater treatment works....and out!In other situations we need to keep water out; precastcan be used for flood protection, river and coastalbarriers to protect against inundation from high tidesand storms. On a domestic scale, precast is also usedfor basements where below ground living needs robustand waterproof construction.20 21

Structuresfor todayandtomorrow22 23

Durable...Concrete buildings from hundred of years ago are still inuse today. Some say concrete can last up to 2000 yearsand there are certainly many structures around that arewell on their way to such a ripe old age......because it getsstronger every day.Precast concrete goes on increasing its strengthfor hundreds of years after it is cast. What’s more,during that time it won’t shrink, warp, move orcreep excessively so can be relied upon to performconsistently year after year.24 25

Structurallyefficient...Quality in design and production means precast unitsare extremely structurally efficient; they have a highspan/depth ratio and EC2 makes provision for reducedpartial safety factors for precast, in acknowledgement ofthe controlled production environment....which means it’seasier to go high.Tall buildings of up to 80 storeys can be built withprecast because of its structural efficiency results in alower storey height (reduced floor depth dimension forthe same span as other materials) and so it becomeseconomically possible to add more floors.26 27

Intelligent.Sometimes it may be helpful to know how a structureis performing over time. Microchips can be embeddedin precast concrete to log data on movement orstress. Engineers can easily ‘read’ the data on thechip by swiping a reading device across the surfaceof the element.Can indicatedistress.In particularly sensitive applications, these samemicrochips can send a signal to indicate excessivemovement or impact. This is particularly useful forbridges and tall buildings.30 31

Can achieve highstrengths.In civil engineering applications high strength concrete isoften desirable, and precast units can be cast to meetsuch demands. If high early strengths are needed, thenthis can be achieved through several means includingself-compacting concrete.Can supportheavy loads.Where point loads or high bearing stresses are likelythen the dense, high quality concrete in a precastelement is absolutely critical. Industrial applications,utilities and power generation all provide goodexamples of this.32 33

Resists chemicalattack.For hard-standing, aprons and other paved areas,precast concrete blocks are an ideal choice becausethey are resistant to fuel and oil spills, they can alsobe replaced easily and are widely available.Does not rust.Precast concrete is corrosion resistant and cantherefore be used with confidence in very aggressiveenvironments. For example, precast concrete piers areresistant to the inter-tidal anaerobic attack experiencedin some marine environments. Furthermore, tightquality controls in production mean that cover levelsfor rebar in any application are ensured.34 35

Absorbs impacts.Precast concrete can resist massive impacts, even fromjet planes. So, it is also more than able to cope withday-to-day applications like traffic separation barriers– the precast units absorb the impact from vehicles andslow them down.Protects againstblasts.In extreme applications, blast protection fromexplosions may be a necessary design criteria.Sufficiently reinforced and thickened precast unitscan perform a critical role here.36 37

Less stressrelaxation.Keeping in shape is important and precast is noexception. Some materials ‘relax’ over time, which canbe difficult to account for in design; precast maintains itsshape, size and properties.“Flies throughthe air with thegreatest of ease”Not all precast is heavy and tough; its ability to spanclear distances without propping means that precastbalconies and bridges can cantilever elegantly.38 39

...can also be lightor heavy or...Precast concrete is made from a range of materials,which can be combined to produce different properties.This means that precast can be porous or impervious;it can float or sink, be heavy or light. The possibilities areendless!Can be thin...The use of steel fibre reinforcement in the precastconcrete mix can produce extremely slenderelements. This means that precast can be used insome very structurally ambitious projects.40 41

Amazingarchitectureand finishes42 43

Customisation issimple.Moulds can be designed to be customised – this meansthat parts of a mould can be added or removed toproduce slightly different sized or shaped units. This isan economical way of customising precast panels andresults in well-matched and compatible units.Has the potential tobe made in any shape.The casting process for precast concrete takes place ina controlled factory environment and uses the skills ofmould-makers to create straightforward or unusualshapes. Manufacturers can offer helpful advice on howto achieve difficult architectural forms.44 45

Blends in withexisting structures.In areas of historic or architectural importance, it maybe important to ensure that any new buildings matchor are sympathetic to their older counterparts. Carefulmix design in the precast factory and use of mock-upscan ensure that the match is satisfactory for all thoseinvolved.Can replicatepatterns, shapes orother materials.Just like the previous advantage, the ‘mouldability’ ofprecast means that it is an excellent mimic, whetherthis entails copying classical details like keystonesand capitals or matching the finish of materials likeweathered stone.46 47

Can be straightor curved...For external walls or cladding panels, the shape of aprecast unit is called its ‘profile’. In these applications,being able to produce a variety of different profilescan be very important and this is an area in whichprecast concrete excels because of the flexibility andaccuracy in the production process....or highly-detailed.The level of detail on a wall or façade is often referred toas articulation - this term is used to describe the levelof complexity on a surface. Casting precast concretein carefully constructed moulds means that very highlyarticulated panels can be made.48 49

Available in a widerange of colours...There are many different aggregates and additions thatcan be incorporated into precast concrete elements,depending on what is required. This gives designersconsiderable scope to produce subtle or contrastingcolour-ways....including whiteand black.Dramatic architectural projects call for dramatic colours,and precast can be used to provide white, off-white orblack shades. Colours in precast are long lasting andmanufacturers can always advise on suitable colours forparticular applications.5051

Can be cut to suit.Considerable flexibility can be built into precast concrete.Not only can window and door shapes be created, butthere is scope to design elements so that they are morelightly reinforced in some areas – these can then be cutthrough at a later date, should perhaps the client wish toadd a door between two rooms.Perfectly precise.The accuracy and factory controlled conditions in aprecast factory are ideal for producing very precise,sharp details. This relies on the craft-based skillsof mould makers and through their expertise, evenminute details become feasible.52 53

Uses special effects!When precast concrete is cast in the factory, thereis an option to lay down different coloured layers ofaggregates in the mould, so that when the surface isexposed to varying degrees the colours can really comealive, producing a spectrum of effects over a relativelysmall area.Can incorporatelife-size images.By using a process called photo-engraving, it is possibleto turn precast concrete elements into huge photoalbums! A dot matrix of the selected photo or graphicimage is effectively reproduced in the surface of theprecast element, so it will not fade or wash away overtime. This technique is often used to dramatic effect.54 55

Smooth.In the same way that natural stone is prepared, precastconcrete can be polished to a smooth and in somecases reflective finish. The inclusion of attractiveaggregates or mica in the concrete mix can help theprecast element to sparkle, adding that bit extra to thequality precast finish.Easily painted.For some structural precast concrete elements, it maybe more desirable to opt for a painted finish. This makesmaintenance easy and it means that colour-ways can bechanged at any point. Precast units are smooth and sopaint can be applied easily and directly onto the surfaceof the concrete itself.56 57

Can be self-cleaning.© Scott Frances/EstoThe optional inclusion of titanium dioxide in whitecement not only produces white precast concrete buthelps to keep the finished product clean. It does thisby capturing dirt particles and then washing themaway during rainfall.Can be designed tochange colour.The inclusion of thermo-chromatic dyes in precastconcrete will cause it to change colour when it reachesparticular temperatures. This is a fun idea, but has seriousapplications too – for example, the concrete can indicatewhen it is too cold or too hot to touch.58 59

...and to others.The same techniques of casting in textures can be usedto increase the skid resistance of the surface of a precastconcrete unit. This can be particularly useful in highlytraffickedpaved areas, steps and ramps where, forexample in winter, icy patches could cause slips and falls.Acts as an aidto visuallyimpaired people...It is common to see textured, knobbly paving slabsnear pedestrian crossings and this is a good exampleof how precast can be made to include textures orprofiles. Tactile paving helps visually impaired peopleto recognise changes in level and possible dangersfrom passing traffic or other hazards.60 61

Quality inproduction andconstruction62 63

...and built toprecise specification.Precast companies work with specialist fixing teams toinstall their products. This guarantees precise, reliableworkmanship ensuring that the quality of service fromprecast is maintained after the products leave the factory.Factory-made...Precast products are produced in factories understrictly controlled conditions. The factory environmenthas a steady temperature, regular shift patterns and adedicated workforce; all this means that high qualityproducts can be made every day, regardless of theweather.64 65

Guaranteed durability.The factory-controlled production process means thatcover to rebar is consistent and correct, as are strengthand concrete quality . Hence the inherent durability ofthe delivered product is assured.Covered by BS andEN standards.The precast industry keeps a keen eye on national andinternational standards – this ensures that customersreceive the best quality products which are compliantto all relevant standards. As well as specific productstandards, many manufacturers also comply with ISO9001 and ISO 14001.6667

Products can beseen in advance...Manufacturers often have vast libraries of samples andmost are able to produce a full-size mock up for theclient and professional team to view. This is a valuableway for all involved to agree which finishes are to be used....and buildings too.Many precast products are available to see every day– buildings, bridges and other structures act asshowcases for prospective customers. Precast concretefeatures on award-winning buildings every year andthese provide some exceptional examples of what canbe achieved.68 69

Great resultsevery time...Having decided to specify precast, it’s important tohave confidence in the solution and this is wherefactory-controlled procedures really become valuable.Repetition of individual units can be achieved withconfidence whether there are one, ten or 100....with long-lastingmoulds.Precast concrete moulds can be stored to allow laterreplication, whether additional units are required oneday, one week or one year later.70 71

Rapid erectionon site.Precast products arrive ready for installation and can bescheduled to arrive ‘just-in-time’ so they can be lifteddirectly into place. This avoids the need for storagespace and unnecessary handling.Bar-codes ore-tags speed upconstruction.The addition of bar coding strips or embedded microchips on precast products help distribution managersidentify individual elements, making sure each reachesits correct destination at the correct time. Thistechnology also helps managers on site speed up theconstruction process while at the same time ensuringaccuracy.72 73

Highly compatible.Because precast is made ahead of time, there’s scopefor designers and those involved with construction toensure that connection details and joints are thoroughlyinvestigated. This can help on site because precastmakes for simple, easy to use connections that speed upconstruction and reduce the risk of errors.Has a key role toplay in hybridconcrete construction.The combination of precast and other materials likein-situ concrete and steel in hybrid concrete constructioncan yield cost and programme benefits. Precastconcrete brings accuracy, high quality finishes and speedof erection to any hybrid concrete construction project.74 75

Protects workforceon roads.It is typical to see precast concrete barriers in placealongside roadworks. These provide workers with safeseparation from the fast-flowing traffic and act as crashbarriers should any vehicles stray off the carriageway.Provides an instantwork platform.Precast structures and in particular floors andstaircases provide an early, secure and broadplatform from which subsequent site activities canbe undertaken. This solid footing helps speed upconstruction and gives managers confidence thatoperatives can go about their work safely.76 77

Improvessafety on site.Innovations to make the use of precast concrete evensafer include air-inflated crash bags, nets and mats.These are used in an area under construction until suchtime as the precast units are securely installed. In theevent of an accident, these break the fall of a worker oreven a whole precast unit.Reduces noisefrom building sites.No vibration, no sawing and no other noise-generatingprocesses need be used to install a precast concretestructure. This results in substantially quieterconstruction sites, which is a genuine benefit to localresidents and workers alike.78 79

Less proneto disruptionscaused byinclement weather.With almost all precast production activities taking placewithin the factory, it is only really fixing that needs to bedone on the construction site. This means that precastis significantly less vulnerable to disruption causedby wet, cold or very hot weather; whatever happens,precast can continue.Easy to cleanand repair.Despite all the best intentions on a construction site,sometimes minor dents, damage or dirtying can occurwhich can compromise the appearance of neatlyinstalled concrete units. The excellent surface finishof precast makes cleaning and repairs easy – mostmanufacturers offer extensive guidance on how bestto undertake these tasks. 8180 81

Protectingpeople and theenvironment82 83

Uses plentiful, local,natural materials...All the materials that go into precast concrete productscome from natural and recycled sources. Aggregatesfrom rocks or river gravels, and water are all widelyavailable and in plentiful supply. With precast there’ssimply no need to import materials from thousands ofmiles make locallyavailable products.Precast concrete products are predominantly, if nottotally, sourced from within the UK. There are over800 precast factories across the country; this localnetwork means travel distances and fuel used duringhaulage are minimised.84 85

Not reliant onoil-based products.A good quality finish relies on achieving a clean breakbetween precast concrete and its casting mould orbed; vegetable-based release agents can be used asa substitute for oil-based chemicals, thereby reducingthe overall environmental impact. In addition concreteis not as vulnerable to increases in oil and gas prices asplastics and asphalt.Uses by-productsfrom other industries.Precast products can safely incorporate materialssuch as blast furnace slag (from the iron and steelindustry) and fuel ash (from coal-fired power stations)that might otherwise go to waste. These materials canimprove the performance of precast concrete and canbe used as partial replacements for Portland cement.8687

Minimum off-factorysite waste exported.Even small amounts of scrap or waste in the processcan be recycled; cement, slurry and process water arerecycled and off-cuts are often crushed and re-used.Made in anefficient factoryenvironment.Today’s precast factories are clean, efficient and manyuse computer-controlled processes for batching,mixing and casting. Working in a factory meansexcellent resource efficiency.88 89

Waste on siteis not lost.Even if all does not go to plan on site, there are stilloptions available with precast. Unused elements canbe used elsewhere. Scrap created at the building sitecan be collected and broken up to create aggregate.Avoids expensiveenvironmentaldisposal costs.Making better use of natural resources makes goodbusiness sense; the Landfill Tax penalises poor use ofmaterials. Using ready-made precast products preventsthe incurring of waste disposal costs.90 91

...or recycled.As with many concrete products, precast is easyto crush and recycle as aggregate. Demand for‘previously enjoyed’ materials like this is growingevery year in the UK – and the government isencouraging its use through networks for suppliersand customers.Can be re-used...At the end of a structure’s life, precast units can bere-used in their entirety, for example reclaimed aswhole elements such as floor slabs. These could bere-installed in the same building or even transporteda short distance and used in a comparable structureelsewhere.92 93

Low embodiedenergy...Like all concrete, during its lifetime precast concretewill effectively re-absorb the equivalent amount ofenergy (carbon dioxide) that was used to createit in the first place! What’s more, using precastdoesn’t require any re-mineralisation (the processof rejuvenating barren soils after they have beenintensely forested)....and reducedin-use energyconsumption.The thermal mass properties of concrete help even outdaily and seasonal temperature swings, making indoorspaces more comfortable without having to resort to airconditioning. This saves both energy and money,not to mention maintenance bills.Cumulative Energy (GJ)700060005000400030002000100000 10 20 30 40 50 60 70 80 90 100YearsHigh Operating Normal Operating Low Operating Embodied9495

Does not leach.Precast concrete is an inert family of products, so itdoes not leach out any harmful chemicals in use. Thismeans it is safe to use in applications like distributionof drinking water. It also means that when precastconcrete is used to store or transport potentially harmfulfluids, these will be contained securely.Reduces the riskof flooding.Permeable precast paving, pipes and soakaways areused in sustainable urban drainage systems (SUDS).These help prevent rapid run-off of rainwater fromroads and pavements by allowing water to permeatemore naturally. Precast concrete flood mats andbarriers protect river banks and livelihoods.9697

Reduces urbanenergy use.The pale colours that can be achieved with precastconcrete finishes help to reflect light, so at night thestreets are brighter and safer. On a hot day, thesesame finishes reflect sunlight, so keeping buildingscooler and preventing the ‘urban heat island’ effect.Can reducetraffic fumes.Using an ingenious materials innovation, precastconcrete coated with a special layer can absorb theharmful emissions from traffic fumes. A process calledphotocatalysis occurs which entraps Sox and Noxparticles, which are then dispersed harmlessly whenrain falls.98 99

Precast isemission free.In its daily use, precast concrete is a totally inertsubstance, so it doesn’t emit or give off any gases,toxic compounds or VOCs (volatile organic compounds).This means allergy sufferers can breathe easy becauseprecast does not contribute to the symptoms of ‘sickbuilding syndrome’.Helps create healthyindoor environments.The simple lines and smart edges of precast concrete areeasy to clean and its hard, smooth finish therefore doesnot accumulate dust which may exacerbate asthma.1001016

The bestvaluesolution102 103

Easy to let.The issues mentioned above attract occupiers aswell as investors, so the attractive appearance androbustness of precast concrete produce a reliablereturn. The architecture and performance qualities ofprecast mean that units can be leased easily.Appeals to investors.The longevity of precast structures and their resistanceto both everyday and extreme events means thatinstitutional investors and other funding bodies tendto look favourably upon the precast option. Thisis particularly well-matched in city locations wherethe solidity and sympathetic appearance of precaststructures reflects the commercial businesses inside.104 105

Lower insurancecosts.With amazing structural properties and functional benefits,precast concrete buildings tend to attract lower insurancepremiums than those built from other construction materials.This can become particularly apparent in high risk areas suchas those at risk from floods, fire and burglary.Easy to extend.The fact that precast elements can be dismantled (ordeconstructed) means that it is easy to add extensionsor new wings to precast structures. Simply remove endpanels and continue building – the end panels can bere-installed on completion.106 107

Lowermaintenance costs.In exposed locations, some structures will need regularpainting to protect against corrosion and enhance theiraesthetic appearance. This is not the case with precastconcrete, which does not require such treatment. Thisadvantage is particularly relevant for roads, bridges andmotorway gantries that cannot be accessed easily.Everyday resilience.Precast concrete is tough and durable and canwithstand everyday maintenance, but it is alsoresilient in the face of intense pressure. For example,used for underground pipes, precast is resistant tojetting (to clean out the system) and on roads or otherpaved areas it provides a durable surface against therutting caused by traffic.108 109

...or a flood.The high quality of precast and the fact that it doesnot erode or rot make the task of clearing up after aflood very straightforward. This can be a difficult timefor people struggling to come to terms with thedevastation that floods can bring, so precast bringsa welcome respite.Lower refurbishmentcosts after a fire...Concrete typically needs very little remedial treatmentfollowing exposure to the high temperatures of a fire.In many cases, some minor patching and a coat ofpaint may be all that is required to make good.110 111

Impressive wholelife value.There’s no doubt that all of the previous 96 advantagesadd up to a significant package – and it is exactlythis idea that convinces people to use precast. Theargument is compelling, precast offers value throughattractive finishes, robust structures and majorperformance advantages such as fire-proofing andthermal mass throughout its life.Peace of mind.The technology behind precast production, designand construction stretches back hundreds of years,so customers can be assured of peace of mind whenspecifying precast products. Precast is a proventechnology.112 113

Productdevelopments...Manufacturers of precast concrete products investheavily in research and development to make theirproducts and services even better. New products,new information technology and new factoriesdemonstrate this forward-thinking attitude....and innovation.This brochure shows that innovation is an everydaypart of the precast world, but we think there’s stillmore to come. We’re keen to hear of new benefits ofusing precast – please send in your suggestions forthe next 100 reasons to info@britishprecast.org114 115

a little book ofConcrete60 Charles Street, Leicester, LE1 1FBTel: 0116 253 6161Fax: 0116 251 4568Web: www.britishprecast.orgEmail: info@britishprecast.orgGlobal 116 Copyright © British Precast Concrete Federation Ltd

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