ARQ - Building Walls-A Philosophy of Engagement

arq . vol 8 . nos 3/4 . 2004 design204

Alan Chandler Building walls

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‘Then a mouse-grey liquid is poured into the emptyspeculative counter forms to give them permanent life onearth, an undeniable reality, especially after the signs ofthe initial madness – the shuttering – have been removed.’(Koolhaas, 1994)

Wall One is part of a series of 1:1 constructionworkshops involving collaborations betweenarchitecture and engineering students at theUniversity of East London (UEL), teachers atEdinburgh University School of Architecture, andCAST at the University of Manitoba, Canada. Theworkshop forum is valuable in developing aphilosophy of engagement between architecturalteaching and practice, treating materials researchand design as facets of one activity. Taking studentsthrough the process of following a theoreticalconstruct into physical construction at 1:1 makespublic their innovative material investigations, andwithin the School of Architecture develops anarchive of test pieces that contribute to the visualculture of the studio [2, 3].

Building Wall One was an exercise in rethinkingthe practice of in situ concrete casting, aiming toestablish new techniques using innovativeshuttering. Innovation can be defined as apurposeful radicalism, which responds to orredefines an existing need or opportunity. It allowsarchitectural teaching to remain relevant, and to useits position outside the standardised context ofpractice to critically examine how and why we build.Concrete is crucial for both structural and thermalperformance, but issues of embodied energy and theresource-intensive casting process affect itsenvironmental credentials. Allied to these financialand energy concerns, there are inseparable visualand theoretical implications to the use of concretethat any research into the material must address.This is particularly true with non-orthogonalgeometry, which the plastic nature of concrete isideally suited to, if only the means of shuttering canbe achieved economically and expediently.

Depending upon how a material is worked, itsexpression, significance and status is capable ofradical variation. This is true of all materials,

however with concrete, it is expressive only when itsprimary quality – that of being liquid – has been lost.The pleasure of working with concrete comesprimarily from its ability to retain a history of itsformer state, of bringing opposing qualities offluidity and solidity together – akin to appreciatingthe potential of fine figurative sculpture to rendersoft human form in marble. It is the method bywhich the material is worked that largely determinesits aesthetic significance, and not the material itself.

In considering the innate plasticity of concrete, themeans of allowing that state to inform the finalresult of the operation led logically to working witha responsive shuttering medium, with the technicalchallenge of restraining a fabric against thehydrostatic pressure of concrete the focus ofexperiment. Allowing flexibility with regard toarranging restraints enabled the form of the wall toemerge as it was being made, the inverse oftraditional shuttering, where the entire final formhas to be fully described in watertight negative, oftenusing expendable materials and resources.Minimising shuttering time and materials use was akey requirement of Wall One.

The Wall One project also sought to address theembodied energy issue of the concrete itself throughthe specification of recycled, manufacturedaggregate. A partner in the workshop researchprogramme at UEL is the MARC programme, based inthe School of Computing and Technology and fundedby the ENTRUST Landfill Tax Credit Scheme. Underthe direction of Darryl Newport, the MARCprogramme recycles waste industrial granularmaterial and organic sewage residues to createaggregates with specifiable size, density and colour.This ‘smart’ aggregate uses selected and metered drypowder resource material which is mixed at1450rpm, then mechanically pelletised usingminimal water content. As with the constituent mix,the size of pellets is also specifiable. Following thedrying of the green pellets, they are heated in a trefoilkiln to vitrify the pellet surface, using thecombustible potential of the organic matter withinthe blend to generate an internal honeycomb withineach pellet: the greater the internal void, the lighter

design arq . vol 8 . nos 3/4 . 2004 205

designExperiments with an innovative in situ casting technique question

assumptions about the nature of concrete, the workmanship of

risk, and the familiar relationship between design and making.

Building walls – a philosophy ofengagementAlan Chandler

1 Wall One: the final lift, with anenhanced surfacedefinition throughthe use of high dustcontent sand in the mix

the aggregate. Because Wall One was situated withinthe main AVA building at UEL, cast onto the existingfloor slab, the lightest specification, containing wastepaper sludge, was chosen. Further recycled materialswere incorporated within the Wall in the form ofshredded recycled plastic to act as an anti-crackreinforcement that has the capacity to flow aroundthe dynamic curved interior of the formwork.

Technique and formMaterials are linked to a resultant form viatechnique. The choice of technique is thereforedecisive, and can potentially allow the dialoguebetween the maker and the cycle of making toregister individual actions within the final builtpiece. Geotextile casting is provocative at a numberof levels: in its material economy as ultra-lightweight, inexpensive containment for concrete;and in the formal dynamic which redefinespresuppositions about concrete and its shuttering,allowing the inherent flexibility of the geotextile toprovide an expressive combination with thehydrostatic pressure of the liquid. The need for

restraint in containing that internal pressure opensup possibilities for the constructor to enter into acreative dialogue with the textile concrete. Work byKenzo Unno in Japan, for example, has taken themass production potential of a technique with fabricto a flawless level, while Mark West at CAST in Canadahas developed fabric formworks to make structurallyand materially efficient beams and slabs.

The work of Unno on casting fabric-shuttered wallsexpresses with beautiful clarity the formal andsurface potential of textile concrete, the technicalmeans by which the concrete is cast beinghauntingly absent from the finished pieces. WallOne is complementary to this work, and its purposelay in determining a process by which the activeparticipation of the maker is registered within thefinished piece, exploiting the material’s naturalbehaviour to create an architectural language ofdetail. To do this effectively, the shuttering needs tobe rethought not only in detail, but alsoconceptually.

The frame that supported the textile during thecasting of Wall One was conceived as a jig, a device for



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holding a piece to be worked, rather than a means ofpre-determining the piece exactly, as withconventional shuttering. This is an importantdistinction if the relationship between theconstructor and the material is to yield an element ofthe unforeseen, to become a means of determining asystematic construction that retains the tactility of acraft process. A jig is a conceptually looser and moreopen-ended mechanism, its precision lying in theclarity with which it enables a range of operations.

To make concrete, water is required for bothchemical change to achieve a solid, and forworkability to enable the flow into its containment.The presence of water in excess of that required forchemical reaction creates minute voids, whichpropagate crazing and create visual defects.Manufactured as an inexpensive subsoil wovengeotextile by the Don and Low Company in Scotland,Lotrak 300GT is an engineered polypropylene weavewith a bleed potential of approximately 160 litres permetre square per minute. This permeability is usefulto leach excess water and entrapped air, delivering aconcrete with low excess water content at the point

of cure. This ‘sweating’ allows a migration of cementfines and sand dust to the inner surface of the textile,giving the concrete enhanced definition andstrength at the face of the cast with a quality almostunachievable with rigid formwork.

The shuttering fabric has inherent properties ofhigh tear resistance and elasticity, with a grab tensilestrength of 1.35kN, and more importantly anelongation capacity of around 15% in both warp andweft, which allows the fabric to respond three-dimensionally to the significant hydrostatic pressureof the pour. The geometry of the textile is utilisedorthogonally with lateral fibres acting in tension.The vertical fibres of the weave act as a jig themselvesto restrain the lateral threads in place. The tearresistance allows for simple bolt through fixingswithout the risk of the openings in the fabricspreading under load. One of the many detailsdeveloped by Mark West involves using a marlinspiketo force apart the weave, allowing the insertion offixings through the material. The weave thusremains unbroken, allowing it to retain its integrityand to be fully re-usable.

According to Gottfried Semper, the geometryinherent in materials is the basis for an architecturallanguage, with the original wand-maker as the proto-architect organising woven fabrics to define a thirdskin beyond the second skin of clothing as elementalprotection. The weave, for Semper, through historicdevelopment came to generate order, pattern andscale for defining the wall as a tectonic element(Semper, 1989). The consequence of a textile-basedcasting medium is directly analogous to Semper’s


Building walls Alan Chandler

2 ‘To be an architectmeans, of course,the desire to build’(Prouvé, 1971)

3 ‘When the[student] has madehis choice, he mustbuild immediatelyat the college,which will havebeen transformedinto a factory or apractice’ (Prouvé,1971)

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idea, engaging the structural potential of a fabricmaterial to create deflections and pressure points,transitions and connections which constitute anarchitectural presence. The expanded geometry thatbecomes available using fabric erodes the pre-eminence of the extruded plan and a modernreliance on the manufactured panel as a measure anddictator of constructed form. Textile casting implies,and allows for, non-linear spatial form to develop as aconsequence of the constructive process itself.

Forming the jigThe jig to hold the textile and to allow it to remainresponsive was designed to minimise material useprimarily through sustainable concerns, and with aview to applications in situations with a severelyrestricted economy of means. An interest inBuckminster Fuller’s notion of ‘tensegrity’ as theresolution of forces within the structure itself,converting dynamic loads into dead weight,informed the opposition of cables and tension propsresisting the fluid concrete weight and fabricdeformation [4].

The top rig was designed as a re-usable joisted deck,the base rig being ply with the curved plan form ofthe wall described with a cut-out. The curved baseplan afforded self-stability, and allowed successivecasts to form, with 180 degree rotations of the

formwork jig, a sine-wave wall, taking inspirationfrom work by the Uruguayan engineer Eladio Dieste.The props are ‘readymades’, providing the energy forthe tension without the necessity for elaboratereinvention. Bespoke containment of the fabric wasdevised using ply discs, set out across the surface ofthe cast to define the geometry for the eventualsurface, and control sectional variation. Thespecification of the setting-out would give, weimagined, the ability to contain randomness withinthe process. Given the high puncture resistance ofthe fabric, the circular ply form was chosen less toavoid corners and pressure points, more to allow theanticipated curvature of the fabric under pressure tobe unhampered by orthogonal geometries [5a, b].

In encompassing the steel cable which connectedtop to base rig, the paired ply discs acted as post-tensioning devices when tightened together,augmenting the work of the props. The cables laterbecame part of the formwork imprint due to thewide offsets between the discs. This ability tomodulate the tension field was the mechanism forboth control and lack of control of the surfacetopography and section. A range of section thicknessbetween 100mm and zero was determined by thestudent team, as was the final spacing of the discsacross the surface. In places, this allowed theconcrete thickness to reach over 200mm [6].



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CastingThe initial pour was limited to a 500mm lift, both tominimise the pressure at the base of the fabric, andto deliberately set up a ‘day-work’ joint. The legibilityof the concrete within the fabric was a revelation,with free water sweating through as the concretelevel rose within the formwork. The water contentwithin the mix was increased once the behaviour ofthe fabric was noted. The ability to respond to thedemands of such a construction would beinconceivable without doing a test at 1:1. Theincreased flow now available enhanced the ability tomanipulate the spacing between the ply discs,making the variation in cross section more extremethan originally envisaged, with the responsiveness ofthe fabric encouraging a sense of play with thematerial. Larger discs were made during the pour tovary the scale of the detail [7, 8].



4 The completedformwork

5 a/b The robust toprig transfers thedownward pull ofthe concrete ontothe upward thrust ofthe acro props. Theside panels define

precise verticaledges to the cast,notionally to allowthe wall to becontinued insections, rotated180 degrees eachtime, to create a sinewave wall. The toprig slides up as the

prop tension isincreased throughslotted connections.The steel cablerestraints are visible,which in conjunctionwith paired ply discs on threadedties restrain theconcrete

5a

5b



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7 8

Towards the end of the casting sequence, theinitiative to create a window within the wall spurredthe creation of an aperture frame, complete withspacers and rebates, which was made and insertedinto the fabric as the concrete was being poured. Thiswindow made for a surreal presence in the finishedcast, with the pressure on the fabric so tangiblypresent, having an opening with 25mm thick edgesdefied expectations. The overt expression of pressureand mass was overturned by the actual thinness ofthe wall and fineness of the window edges.

The role of play within research became a questionas a consequence of our experience – the enjoymentof a creative interaction with materials providingnew areas of invention as the Wall progressed. Thesand specification was changed during the secondlift, sharp sand being replaced by Leighton Buzzardsand, to assess how the sweating properties of thefabric affected the sand’s ability to influence thecolour of the final cast, in this case yielding a faintpink hue.

The final lift provided a further opportunity tochange sand, to one with high dust content [1]. Thedust is finer than the cement fines that areconventionally the smallest element of the matrix,so with the sweating bringing the fines to thesurface, the dust radically affected the colour of thecast and the surface definition. As a side effect of thesweating, the concrete achieves a striking capabilitywithin 24 hours, enabling the entire 3 by 2 metrewall to be completed from unloading supplies tostriking the formwork within five days. Theenthusiastic support offered by Allan Haines of theConcrete Centre means that the advantagesdiscovered with this technique have a potentiallyuseful future, with the speed of formwork erection;short pour to strike time; high-strength, low watercontent matrix; and blowhole-free surface givingdistinct advantages to construction projects.

Process, form and riskAn architectural prototype acts as both ananticipation of the end of a process of thought and asan enactment of that process. A prototype’s powerlies in its ability to embody a field of ideas and themeans of testing the interrelationship of those ideasin a single moment: making a prototype acceleratesthe proposition. The task for Wall One was toconceive of a prototype construction process whichwas both a practical, repeatable technique, yetwithin its own operation allowed for andencouraged the constructors actively to manipulatethat process. The exact placement of restraints, theirsize and degree of constriction, could bemanipulated even as the concrete was poured,

questioning the need for the extensive pre-determination required of conventional concretework. The casting technique of Wall One showed thatfrom a coherent technique, unpredictable, evenincoherent, detail might emerge – an architecturalequivalent of the Surrealist game of the ‘ExquisiteCorpse’. This subversive intention was at the heart ofthe Wall One exercise, and formed a critique ofindustrialised building processes by addressing thevery aspect of construction that causes mostdifficulty – risk.

In his book The Nature and Art of Workmanship, DavidPye distinguishes between the ‘workmanship of risk’and the ‘workmanship of certainty’. He clarifies therole of the individual maker with regard to eitherbeing involved with the determination of the result,or being placed outside of a pre-determinedmechanical or digital process. He asks us to look atmeans and ends. The ‘workmanship of risk’ reflectsthe ambiguities surrounding the reality ofarchitectural practice: ‘In the workmanship of risk,the result of every operation during production isdetermined by the workman as he works and itsoutcome depends wholly or largely on his care,judgement and dexterity’ (Pye, 1968). In other words,can one determine the accuracy of a built resultmore confidently by using techniques which do notprescribe the outcome entirely, but ratherincorporate adjustment and judgement within theiroperation?

With much of architectural production focused onone-off buildings for particular users and locations,it is vital to address the issues surrounding bespokeproduction, of equipping architects to exercisejudgement and dexterity both at the design andproduction stages of building. The issue foreducation is to equip students to actively manage thepractice of risk, and to define a means of operatingthat enhances the potential within any givensituation. But how can one teach the management ofrisk when increasingly the framework of teachingitself is becoming risk averse? Essentially, risk needsto become a focus of activity, not a pariah to beavoided. Building at 1:1 using innovative techniquesplaces a responsibility upon the participants to useintuition and lateral thought to re-think bothprocesses and material languages, and to define newand safe working practices in the process.

The drawing, with its inherent abstraction,normally precedes the making of structures withmaterial. Within the Workshop this need not be so,and the line loses its pre-eminence. Workshops relyon both verbal and manual exchange in order togenerate the constructed situation between theparticipants and their task. The student is taughtnever to assume that the mastery of matter is alwaysthe responsibility of others. In the very conception ofa design the qualities and properties of materialsmust be grasped and understood in order to make.

The practice of prototyping is a proper domain forarchitectural research. Constructive processes andmaterial inertia need to be thought of not asimpediments to formal invention, but rather asactive participants in innovation. As educators and as



6 Deflection

7 The pressure of theconcrete around theretaining discs, held together/apartvia threadedstudding, forces

the geotextile torespond. With a grab tensileresistance of 135 kN,and an elasticpotential of 15%, safe deformationsare possible, and

depending on thespacing of the discs,suppressed orencouraged

8 When the ply discswere tightened untilthey touched



9a



9c

9b

9 a/b/c The final piece, 3m wide, 2m high,between zero and200mm thick

architects, the compulsion should be to build, learnand build again, a mode of operations at odds withtraditional (non-architectural yet dominant)research practice. Conventionally, a discrete series ofoperations would be defined which, throughsystematic and linear processes, became understoodand evaluated according to pre-set criteria. Buildingat 1:1, informed with a limited but effective body ofintuition and understanding, provides a broadplatform from which significant areas of study – ofmateriality, process and technique – can be testedsimultaneously. It is only after the prototype is builtthat the linear model of analysis becomes vital inrefining the opportunities that full-size making hasgenerated. The prototype tests the interaction ofmaterials and events, not merely their constituent

parts. In making a prototype, one discovers how tobuild, and where to focus the activity of risk, thevalue of team consciousness, and the consequencesof theoretical decision making [9a, b, c].

Walls Two and Three have already beenconstructed, pushing further the geometric,technical and material possibilities using bothconcrete and unstabilised rammed earth. With theeffective tensile restraint of fabric used as permanentformwork, tensile weak rammed earth could gainnew structural possibilities, and will form the nextarea of ‘Wall’ investigation. The engagement withmaterials makes innovation both possible andpurposeful: within architectural education,producing only an image of architecture is notenough.



ReferencesThe Architects’ Journal Information

Library (1968). ‘In Situ Finishes’, 14February.

Gage, M. (1969). Guide to ExposedConcrete Finishes, The ArchitecturalPress, London.

CAST (2005). The Centre for ArchitecturalStructures and Technology, see:www.umanitoba.ca/cast_building/.

Koolhaas, R. (1994). Delirious New York,010 Publishers, Rotterdam.

MARC (2005). Manufactured AggregateResearch Centre, see:www.uel.ac.uk/marc/.

Pedreschi, R. (2000). Eladio Dieste,Thomas Telford, London.

Prouvé, J. (1971). Prefabrication:Structures and Elements, PraegerPublishers Inc, New York; London.

Pye, D. (1968). The Nature and Art of

Workmanship, Cambridge UniversityPress, Cambridge.

Semper, G. (1989). The Four Elements ofArchitecture and Other Writings,Cambridge University Press,Cambridge.

Illustration creditsarq gratefully acknowledges:Author, 1, 3, Julia Hartmann, 8, 9Dirk Lellau, 2, 4, 7, 10, 11Jim Ross, 12Tze Ting Mok, 5, 6

AcknowledgementsThe author wishes to thank the Donand Low Company, Allan Haines, JuliaHartmann, Remo Pedreschi, Jim Ross,Signy Svalastoga, Mark West and thestudents who collaborated on thebuilding of Wall One.

BiographyAn architect and teacher, AlanChandler developed an interest inmanipulating casting processes andin using flexible formworks whilestudying at the AA in the early 1990s.He is now leading Technical Studies atthe University of East London, whereconstruction and innovation inthermally massive materials hasdeveloped into a teaching andresearch practice.

Author’s addressAlan ChandlerSchool of Architecture and the Visual

ArtsUniversity of East London Docklands Campus 4-6 University Way London E16 [email protected]

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ARQ - Building Walls-A Philosophy of Engagement