The Potential for Application of Cathodic Protection in Masonry-Clad, Steel-Frame Buildings Author(s): STEPHEN J. KELLEY, MATTHEW E. NOVESKY and GREGORY DOWELL Source: APT Bulletin, Vol. 43, No. 4, SPECIAL ISSUE ON IRON AND STEEL (2012), pp. 33-39 Published by: Association for Preservation Technology International (APT) Stable URL: http://www.jstor.org/stable/41827037 Accessed: 06-03-2015 19:59 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Association for Preservation Technology International (APT) is collaborating with JSTOR to digitize, preserve and extend access to APT Bulletin. http://www.jstor.org This content downloaded from 128.235.251.160 on Fri, 06 Mar 2015 19:59:32 UTC All use subject to JSTOR Terms and Conditions The Potential Protection for in Application Masonry-Clad, of Cathodic Steel-Frame Buildings STEPHEN J. KELLEY, MATTHEW E. NOVESKY, AND GREGORY DOWELL A well-knowntreatmentis used in a new and non-intrusive way to addressthe harmful effectsof corrosionon late-nineteenthand The Developmentofthe Metal-frame and Fireproof Envelope basedin Pittsburgh, was ironindustry, new outlets for its to seek beginning in building productsand saw a future contribuAmerica's greatest Arguably, offered fertile construction.4 Chicago tionto theworld'sbuiltheritage is the withtheeconomicimperative ground, whichwas developedin the skyscraper, forquickreconstruction ofthetall masonryearly-twentieth-century and latterpartofthenineteenth century core. The fire of its business buildings clad, metal-frame buildings. reacheditsfirst zenithin technological theneedforthefirealso illustrated achievement beforetheGreatDepresofmetalframes. Consequently proofing sion(Fig.1). Withina fewshortyears, to fillthis theterra-cotta industry grew thisbuildingtypeevolvedintosteelfirst as fireproofing buteventually need, framestructures thatwereclad in mawithdecorative shapesand sophisticated sonry.Thosewho maintainand repair exterior used for glazes cladding. thesebuildings knowthatcorrosionof WilliamLebaron Chicagoarchitect and anchorsis embeddedsteelmembers concerned aboutdifferential Jenney,5 in themaa commoncauseofdistress movement betweenframeandcladding, sonrycladding. deviseda practicalmethodto hangthe constructed offerBy1850 frames ofeachfloorindependently on cladding ofarchitecrousmetal,theworkhorse themetalframeusingshelfangles.6 turalmetals,couldbe seenas thewave was an avidreaderoftechnical Jenney ofthefuture. Firstutilizedin bridges, and Frenchtrade articlesinAmerican and and warehouses, factories, wrought It is possiblethathewas journals.7 castironwerecomingintowidespread surVarchitecture awareoftheEntretiens in theEastuse forbuilding construction andtheorist written Frencharchitect by urbancenters ofthe ernand Midwestern Emmanuel which Viollet-le-Duc, Eugène UnitedStates.1 Attheconstruction site, intoEnglishin 1875 had beentranslated partswerequicklyassemprefabricated archiand was availableto American and thisspeed bledand boltedtogether, wroteoftheprobtects.Viollet-le-Duc, incombination withthe ofconstruction, lemscausedbymetalcorrosion setinto costsavingsthatcouldbe achieved, will "thiskindofmaterial masonry, andwholesalers.2 appealedto merchants ironletintostone-work that; destroy The development oftheBessemer and burststhe oxidizes,decomposes, processin Englandin 1856 madeit warnstone."8DespiteViollet-le-Duc's of possibleto producelargequantities American architects continued to ing, malleablesteelthatpossesseddesirable ironand thensteelas emusewrought tensileand compressive and consistent beddedanchorsin stone,brick,and that properties surpassedthoseofcast terra-cotta a systems, masonry-cladding iron.3Steelproduction and wrought wellintothetwentrendthatcontinued usingthisprocessbeganintheUnited tiethcentury. Statesinthe1870s.However,thetransiBurnham and By1890 architects tionfromironto steelwas gradual,and Tribune Tower, by Fig.1. TheChicago designed Root a steel had complete developed HoodandJohn MeadHowell. The ironwerestill bothcastand wrought Raymond in for Rand frame the McNally Building result ofaninternational competition, usedin building design construction as lateas The firm also developeda steel this450-foot-tall, steel-frame was Chicago. skyscraper the1890s. in cladinIndiana limestone andwascompleted witha diagonal framelaterally stiffened to the1871 ChicagoFire, Coincident thecladding hasbeen 1925.Inthisimage for the Masonic 20-story bracingsystem whichafforded theneedfornewtall the installed abovethefifth floor andthrough in Burnham's Temple(1892) Chicago. oftheTribune eleventh floor. to be constructed the Archives, buildings Courtesy quickly, RelianceBuilding(1895),also in Chi1924. 33 This content downloaded from 128.235.251.160 on Fri, 06 Mar 2015 19:59:32 UTC All use subject to JSTOR Terms and Conditions 34 APTBULLETIN: JOURNAL OF PRESERVATION TECHNOLOGY /43:4,2012 NewYork, Fig.2.TheReliance Building, Chicago, designed Fig.3.Woolworth Building, designed intheoffice ofDaniel Anarchetype Burnham. of byCassGilbert. Cladinterra cotta andcomtheChicago School ofarchitecture, in1913,theWoolworth constructionpleted was Building in1890andcompleted in1895.Therigid labeled the"Cathedral ofCommerce" duetoits begun steelframe wascladexclusively with neo-Gothic At792feet, itwasthe highly design. ornamented terra cotta. world's tallest whencompleted. Photograph byL. skyscraper 1998. 2004. Schwartz, Photograph byS. Kelley, NewYork, Fig.4.TheMcGraw-Hill Building, Hoodinconjunction with designed byRaymond in andFouilhoux, 2004.Completed Godley inthetenets wasrooted of 1931,thisbuilding theInternational andalsoillustrated the style oftheGreat ethic. The pragmatism Depression terra-cotta facade wasstripped ofalmost glazed allornament. Photograph byS. Kelley. a rigidframe, rather cago,incorporated thanbracing, andwas thefirst skyas a scraperto useterracottaexclusively cladding(Fig.2).9 a civilengiJosephKendallFreitag, neerandprolific oftechnical writer thisnewskyscraperbooks,described whichwouldbe method, building adoptedforusewellintothetwentieth century: Ifbuildings aremadefire-proof and entirely, haveskeleton construction sodesigned that their wallsdonotcarry theweight offloors enclosing orroof, then their wallsshallbenotlessthan inthickness; twelve inches andprovided, also, that suchwallsshallbethoroughly anchored to theironskeleton.10 Freitaggoeson to statethat"thebuildmorenorlessthan ingbecomesnothing a vitalskeletonofsteel,withan architectural and protective wrapperof or inside terra-cotta, tile, brickwork, and outside."11 ofthetwentieth Bythebeginning had century skyscraper development movedfromChicagoto New YorkCity. Theonce-impressive 20-story buildings ofChicagowereovershadowed bytaller New Yorkskyscrapers and finally by Cass Gilbert's Woolworth 57-story BuildBuilding(1913). TheWoolworth curtainwallsreplacethemasonry walls thathad becomethesystemized building fortheprevious70 years. technique in ingutilizedthelatestdevelopments steel-frame butitsmaconstruction, sonrycurtainwallhad notvariedfrom thatofitsantecedents (Fig.3). FollowingWorldWarI, America entered a secondskyscraper era,which a demand for increased brought speedin and erection. This reached era its design peakwiththeEmpireStateBuilding (1931),whichwas completed duringthe GreatDepression.Architect H. R. Dowsellwroteofhisfrustrations with thelimitsofmasonry cladding:"Traditionhas clungto theheritage ofthick walls. We inherited masonry masonry wallsand seemunableto outgrowour inheritance. The ideathatmasonry is the construction onlyformofpermanent was so deeplyrootedthatpractically all codes made walls building masonry mandatory."12 The 1930s saw a simplification of detailinthefewskyscrapers thatwere constructed duringthisdarkperiod,but thesamemasonry claddingwas utilized construction (Fig.4).13Whenbuilding resumedinthe1950s,an entiregenerationofbuilding-construction expertise had beenlost;in addition,theInternationalstyledictatedthatglassand metal CorrosionPathologies A significant ofmasonry-clad pathology steel-frame buildingdatingfromthe mid-1880s through theGreatDepressionis corrosioncausedbywaterinfiltrationintothemasonry wallandthe consequentdamageto thesteelframe and surrounding cladding. or oxidation, is thegradCorrosion, ual lossofmetalsolidsdueto electroIn thisprocessthe chemicalreactions. metalreverts fromitsunnatural refined stateto itsnaturalore.Oxidationofa can steel-frame, masonry-clad building be comparedto an electrochemical cell or battery. Batteries havethreeparts:an anode,a cathode,andtheelectrolyte. The cathodeand anodebothneedto be withintheelectrolyte. Thechemical reactionbetweenthecathodeandanode causea build-upofelectrons at the theelecanode,whichflowthrough towardthecathode.A consetrolyte quenceis oxidationthattakesplaceat theanode.14 This content downloaded from 128.235.251.160 on Fri, 06 Mar 2015 19:59:32 UTC All use subject to JSTOR Terms and Conditions INMASONRY-CLAD, STEEL-FRAME BUILDINGS35 CATHODIC PROTECTION ofweldablesteel,or boltingon-ofaddision.Intergranular rather corrosion, locathangraphitic tionalmetalto thecompromised corrosion, occupiesa withweldinginmuchgreater tions.Shortcomings volume(4 to 10 times) cludethemandatory useofmildsteel, thantheuncorroded metaland,when in will much on which corrode thefuture, wreaks havoc confined, building likethemember facades(Fig.5). Becauseoftheabsence strengthened. being in steel,thecorroofunalloyedgraphite fieldweldingcan damage Furthermore, whichmustthenbe sionproductshavelittleor no strength protective coatings, into or adherence and flakeoffas theyare repairedandcan createcrevasses the thuspresenting freshsurfaces whichwatercan settle, formed, offering forfuture corrosion.17 forfurther corrosion. Bolting potential newsteelpiecesto theexisting steelis Corrosioncan occurat embedded ofthedestructive Fig.5. Inthisillustration to notwithoutchallenges. Becausea nut anchors,whichwereuseduniversally effects oflamellar a steeltubular corrosion, ofthebolt anchor and terra at must be installed at the back stone, brick, cotta; handrail theconcrete into posthasbroken in the bore shelf that the of holes, requires angles weight existing repair support itwasset.Photograph which S. by Kelley. themasonry curtainwalland areatremovalofadditionalbackupmaterials to provideaccess.Ifboreholesarenot tachedto thestructural frame;and in Metal-frame arehighly buildings steelmustbe drilled the structural frame itself at columns present, existing to theeffects ofelectrochemsusceptible in to install thebolts.Ifa nonand beams that are contact and tapped spandrel icalcorrosion becauseall ofthecondiwith the wall or are otherwise ferrous such as stainless steel,is metal, masonry tionsarepresent to initiate an electroclose to the exterior. The tellused for then strengthening, potential building chemicalreaction. The metalframeand talesignsarefamiliar and similarto the galvaniccorrosionbetweendissimilar embeddedmetalcomponents can prodescribed Viollet-le-Duc 150 metalsmustbe addressed. process by videbothanodicand cathodicregions iffeasibleby and Memberreplacement, yearsago byexpanding breaking thatareaidedbytheconnectivity ofthe Manifestations of the nature of the wall and structural masonry components. metalframe, whichcompletes theelecin allows the use of stainless steel corrosion include assembly, masonry envelopes trochemical circuit. Thesecomponents rather than mild steel. cracks that mirror metallic members Replacement areembeddedinmasonry and mortar, members areboltedintoplaceina within, spallsat embeddedanchorlocawhich,whenwet,proveto be an ademannersimilarto thecompromised cracksemanating from tions, diagonal quateelectrolyte. Atmospheric oxygen shelfangles,and in-planeand out-ofmembers beingremoved. Again,the aidsintheoxidationprocessofthesteel for corrosion mustbe of assempotential galvanic planedisplacement masonry to produceferrous oxide(rust). addressed. blies. Castironis subjectto graphitic also knownas dealloying or corrosion, Traditional selective MitigationStrategies leaching.Greycastironhas a (an allotropeofcarbon)congraphite Therearethreetraditional methodsto tentof3 to 4% byweight, and this addresscorrodedsteel:repair,strengthnetwork is leftbehind porousgraphite Each approach ening,and replacement. andis impregnated withinsolublecorroof the requiresdisassembly masonry sionproducts as theironleachesaway. wall,withpotentiallossoforiginal As a result, thecastironretainsits to rematerials thatmaybe difficult appearanceand shapebutis weaker In someassemblies, such placein-kind. Thesecorrosion structurally. products as decorative cornices,balconies,or areverydenseand adherent, haveconcolumns,thesetraditional approaches siderable and form a barrier strength, can becomeso intrusive as to call the corrosion.15 Moreimporagainstfurther ofrestoration intoquestion feasibility thereis notan expansionofcortantly, 6). (Fig. rosionproductthatdamagesmasonry Ifstructural members arenotsignifiassemblies withinwhichitis buried. cantlycorrodedor structurally comproalso known corrosion, Intergranular and mised,thenexposure, cleaning, as lamellarcorrosion, proceedslaterally painting oftheaffected steelis an adefromthesitesofinitiation alongplanes Forembedquatemitigation strategy.16 corroparallelto thesurface, forming dedmetalanchors,replacement is the sionproducts thatforcemetalaway onlylogicalmitigation strategy. SanFrancisco, deFig.6.TheRussBuilding, fromthebodyofthematerial, giving Ifstructural ofthesteel integrity W. Kelham. Traditional steelsigned by George riseto a layeredappearance.Ironmemmembers is compromised, thenstrength- frame ontheexterepairs being implemented berswithelongated grains(fromrolling rior terra-cotta facade ofthis1927building, eningor replacement maybe required. orextruding), suchas steelandwrought inmany cases,areintrusive though necessary either weldStrengthening mayrequire andcanleadtothelossofvaluable historic iron,aresubjectto thistypeofcorroif the member is ing, existing composed fabric. ofWJE, 2000. Courtesy This content downloaded from 128.235.251.160 on Fri, 06 Mar 2015 19:59:32 UTC All use subject to JSTOR Terms and Conditions 36 APTBULLETIN: JOURNAL OF PRESERVATION TECHNOLOGY /43:4,2012 Field andCompany as seenfrom Fig.7.TheMarshall Building, Chicago, ina historic thenorthwest postcard. embeddedanchorsinthe Existing notattachedto wall, masonry typically themetallic can be removed, frame, and replacedwithsimilar discarded, anchorsmadeofa nonferrous material, suchas stainless steelor bronze. A New Mitigation Strategy A relatively newstrategy to address corrosionin masonry-clad, steel-frame thathas beenusedbythe buildings authorsis cathodicprotection. Since corrosionis an electrochemical process, theidea is to introduce anodescomnoblemetalsintothe posedofhighly and to masonry claddingat setintervals an electrical current intothe impress anodesso thattheirelectrons move towardtheexisting steelframe, making thatframeentirely cathodic,which ceasesfurther corrosion. The highly nobleanodeswillbe consumedslowly as theyoxidizebutwillnotchange and willnotcausedamdimensionally age to themasonry. Cathodicprotection defines a general areaoftechnology thatencompasses bothsacrificial cathodicprotection cathodic (SCP) and impressed-current chemist and (ICCP). British protection inventor SirHumphry Davyproposeda formofSCP in 1824: ironor primitive zincelements installed belowthewaterlinethatwouldserveas anodesand corrodesacrificially alongsidethecopper hullsofwarships.18 The SCP technique in wouldbe usedextensively eventually andwetsoils.19 aqueousenvironments tothetwo-story, terra-cotta-clad column elements onthe Fig.8. Repairs north facade oftheMarshall Field andCompany thedamHere, Building. units havebeenremoved. agedterra-cotta byL.Schwartz. Photograph SCP requiresa sufficiently conductive is one oftheworld'slargestand most to allow the electric current famousdepartment stores.Completed electrolyte in 1907, itwas constructed in four to flowfromthesacrificial anodeto the metal.ICCP,on theother corroding phasesaccordingto theplansofDaniel an externally thebuilding hand,impresses Burnham, applied fulfilling proelectric current fromthe protective gramplannedbyitswealthyowner MarshallField(Fig.7). anode,thusallowinga "push"foreleca more resistive elecThe Annexwas constructed in 1893 trolytes though In addition,theanodesaredeat thesoutheast corneroftheblockand trolyte. inertmaterials thatare is theearliestbuilding thatstillon the signedofhighly consumedveryslowly.ICCP foundits site.It is a marble-and terra-cotta-clad, inthe construction metal-frame thatis ninestories wayintobuilding building in height. inserted anodes The threebuildings thatfol1970s,whenengineers intoreinforced-concrete lowed were all steel-frame structures, 12-story, structures and ofthesamearchitectural mainlybridges, garages,and roadways. In 1991 anodesand wireswereintrocornerin 1902, style- thenorthwest ducedintothesteel-frame, cornerin 1907,andthe masonry-clad southwest entrance colonnadeto theRoyalCollege northeast cornerin 1914. The facades ofSciencein Dublin,Ireland.Sincethat StateStreet wererendered overlooking in have but those time,cathodic-protection systems mainly granite, lookingover beenincorporated intoa handful of and Wabash streets wereclad Randolph intheUnitedKingdom, structures inwithglazedterracotta.Todaythey Gloucester remainas constructed, cludingtheterra-cotta-clad exceptforthe Road Underground Station(1906) and unfortunate removaloftheprojecting theDanielBurnham-designed cornicesinthe1950s.MarSelfridge's terra-cotta in Store and London shall Field was listedon theNational (1909) Department thebrick-and terra-cotta-clad of Historic Placesin 1978. Joshua Register ArkIn 2000 theauthorswereretained to HoyleBuilding(1904), stone-clad House (1927), and brick-clad thecondition ofall ofthe wright investigate Kendal'sDepartment Store(1939) in facadesofthebuilding. The eleventh Manchester. and twelfth floorsofthebuilding are recessedapproximately 6 feetfromthe mainfacade,expressing thestructuralCase Study:MarshallFieldand steel columns. The terra-cotta building CompanyDepartmentStore facadeson thenortheast quadrantofthe The MarshallFieldand Companystore fluted buildinghave23 two-story-tall, in Chicago,whichfillsan entireblock terra-cotta-clad whichare columns, boundedbyWashington, State,and partially engagedintothewallbehind and WabashAvenue, Randolphstreets (Fig.8). The terra-cotta claddingat This content downloaded from 128.235.251.160 on Fri, 06 Mar 2015 19:59:32 UTC All use subject to JSTOR Terms and Conditions BUILDINGS37 INMASONRY-CLAD, STEEL-FRAME PROTECTION CATHODIC and theterra-cotta Fig.9.Worker checking todetermine itsresistivity to back-up masonry electrical current with a custom-designed theanodesystem Ohmmeter sothat maybe laidout.Photograph byS. Kelley. properly thesecolumnswas observedto be extensivelycrackedand spalled.Yearsof hadcausedcorrosion waterinfiltration steelcolumnsand oftheunderlying lateralanchors.The expansionfrom corrosion on thecolumn intergranular invertical and resulted cracking flanges spalling. Strategies Mitigation unitswouldbe replaced,and undamagedunitswouldremainin place. suchas Somein-situ stabilization, withnonterra-cotta-unit pinning metallicdowels,wouldalso be undertakento salvageas muchhistoric material as possible. The traditional repairoptionat the columnswouldhavebeenextremely andwouldhaverequiredfullintrusive and mascaleremovalofterra-cotta sonryback-upat eachcolumn.Muchof theterracottawouldnothavebeen muchofthe and therefore salvageable, havebeen fabric would originalbuilding lost.The costoftheremovaland reconwas prohibitively struction expensive. The clientconsidered claddingmaterials otherthanterracottato addresscost concerns. inthis ICCP offered someadvantages and It was muchlessintrusive instance. ofterra-cotta wouldallowthemajority unitsto remainin place.The costof ICCP was halfofthatfortrainstalling ditionalrepair.However,further testing it whether to determine was required feasible. was practically was thatthis One disadvantage installed ICCP system wouldbe thefirst in a masonry withintheUnited building to unfamiliar States;itwas therefore clientsand tradespeople. American with discrete anode, Fig.10.Aneedle-like hasbeen attheendforthewire, connection thewall. andisready tobesetinto assembled byM.Novesky. Photograph inpositive and resulted wereperformed results. whichconNext,a trialinstallation, ofan sistedofthepartialinstallation was performed at two ICCP system, adjacentcolumns.ThetrialICCP system was runfrom18-voltbattery packs andconnected placedinsidethebuilding columnswithwires to theexterior thewindows.TheICCP system through overthenextyearto was monitored ofthe thesuccessful polarization verify thattheinisteelcolumnsandto verify and spacingof tialcalculatednumber for Testingthe ColumnsforSuitability ICCP a mitigaBasedon close-upinspections, oftheICCP sysTo testforsuitability was recomtionand repairprogram to determine: it was tem necessary the mendedthatincludedaddressing • terra-cotta of the the inthe conductivity causesofthedistress underlying and masonry back-upto determine terra-cotta columncladding.Two repair as an electrolyte theirsuitability (Fig. optionsweredeveloped: 9) • Traditional all of Removal of repair. • whether themasonry theterra-cotta back-upand claddingto exposethe in continuous mortar were for structural-steel column placed underlying contactwiththesteelcolumns,so cleaningandpainting. Salvageable thatthemetalis surrounded terra-cotta unitswouldbe repaired bythe New terracotta andreinstalled. electrolyte wouldreplacetheunitsthatcould • thecontinuity to ofthesteelframe, notbe salvaged. current electrical negative support • Installation .A • thecorrosion ofan ICCP system rateofthesteelcolumn wouldbe cathodic-protection system • thepreciselocationofeachembedded installed, everysteeleleconnecting anchor mentto a negative chargeand insertand in-situ analysesof Laboratory chargedaningdiscrete, positively materials, openingsat the inspection surfaceof odesthrough theexterior corrosion-rate and connectivcolumns, thecolumncladding.Onlysignifiand a metal-detector survey testing, ity cantlycrackedand spalledterra-cotta system remote-monitoring Fig.11. Ahalf-cell column tomonitor wassetinto eachterra-cotta tothesteel flow from theanodes theelectrical andembedded anchors. frame by Photograph S. Kelley. This content downloaded from 128.235.251.160 on Fri, 06 Mar 2015 19:59:32 UTC All use subject to JSTOR Terms and Conditions 38 APTBULLETIN: JOURNAL OF PRESERVATION TECHNOLOGY /43:4,2012 enceelectrodes, column,and embedded anchorsweredesignedto be durable. The masonry workincludedreplacementofdamagedterra-cotta units; ofcrackedterra-cotta unitswith pinning in rods set Fiberglas-threaded epoxy(the useofa nonconductive material was so as notto adversely affect necessary theICCP system); and deepgrinding and repointing ofall joints. The construction teamwas composed - twotrades ofmasonsand electricians thatrarely, ifever,workhandin hand. ofhowtheICCPsysThe projectwas described to theworkFig.12.Simple diagram temfunctions atoneofthecolumns; (A)maersat thekick-off as a large meeting (B)terra-cotta (C)steel unit; sonry back-up; that were to construct battery they (Fig. and(E)DCpower (D)anode; column; supply. 12). The masonswhohad preparedthe Thepower needed torun theentire ICCPsyswouldneedto temattheMarshall Field andCompany Building mortarjointsforpointing isequivalentto that needed topower oneortwo treatthewiresplacedwithinthesejoints incandescent bulbs. light Drawing byG.Dowell. bytheelectricians withgreatcare.The workers weretoldthattheworkwould anodesinstalled was producing theapbe validateddailyto confirm thatthe to the steel member. ICCP was operating propriate protection properly. Any Resultsfromthetrialrepairsindicated locationsnotregistering would correctly thattheterra-cotta columnswereconneedto be revisited and testedlocallyto ina mannersuitableforthe structed isolatethediscontinuous area.The installation ofan ICCP system. from repairprojectwas performed withbothtrades suspendedscaffolding sidebyside,integrating thetwo Installation ofICCP working systems together. In 2002 a mitigation and repairproject The masonswereable to locateall was implemented on the23 terra-cotta embeddedanchorsbasedon the project columnsusingICCP. The electrical and drilled1-inch-diameter drawings workincludedtheinstallation ofthe pilotholesinthemortar jointsto expose following: them.The electricians thenconnected • negative connection to eachofthe theanchorsto eachotherwithwiring steelcolumns thebedjoints(Fig.13). Once through • negative theelectricians installed thewiring, the wireconnection to each the embeddedanchor jointswerethenpointed,concealing 14). • installation wiring (Fig. ofand positive-wire The completed ICCP system was connection to discrete anodeprobes zonedso thateachofthe23 columns (Fig.10) couldbe monitored separately (Fig.15). • installation ofreference electrodes To date,thesystem is stilloperating, • wiringsystem froman interior electri- thoughownership ofthebuilding has cal sourceto eachanodeprobe oftheproject. changedsincecompletion • a remote-monitoring The system can be monitored to meabythe system controlpanelinstalled on theupper surecurrent flowthrough thereferfloorsor remotely enceelectrodes bythemodemcon(Fig.11) nection that was partoftheICCP instalThe reference electrodes wereinlation package. stalledat eachcolumnto continuously monitor thesystem and measurethe desiredflowofcurrent. Conclusion The probesand reference electrodes weresetina carICCP systems haveprovento be a valid bonaceousfillto promoteconductivity. toolwhentreating corrosionproblems Eachanodeprobewas composedof on masonry-clad, steel-frame buildings inertmixed-metal oxide(MMO) witha ofa specific era.However,testing is 500-0hmballastresistor. The connecto determine that suitable required tionsofthewiresto theanodes,refer- between terra-cotta units Fig.13.Thejoints wereground outtoa depth ofatleast1 inch andwereusedtoinstall thewiring tothe embedded andremote monianodes, anchors, which wereallinstalled orlocated atmortors, tarjoints. Photograph byM.Novesky. conditions existforitsuse.ICCP will notreplacetraditional restoration, and repairtechniques. A maintenance, offers the cathodic-protection system to be installed advantageand variability at limiteddiscrete areasofbuilding facades.In thecase studypresented, ICCP providedtheopportunity to installa less-intrusive repairso thatoriginal buildingmaterials werenotlost.It also provedto be an economicalapproach,witha costofabouthalfofthat oftraditional repair. The completed projectalso revealed someotherimportant If considerations. exterior has alreadycracked, masonry beencomprodisplaced,or otherwise mustbe admised,theseconditions dressedbeforeor intandemwithICCP Fig.14.Mortar joints being pointed bythe crewoncethewires weresetinplace. masonry Photograph byS. Kelley. This content downloaded from 128.235.251.160 on Fri, 06 Mar 2015 19:59:32 UTC All use subject to JSTOR Terms and Conditions INMASONRY-CLAD, CATHODIC PROTECTION STEEL-FRAME BUILDINGS39 of0.2%orless)andironsilicate conductive andionstomove (orslag)that pathforelectrons areinphysical, rather thaninchemical oralloy, from onemetal totheother. Onemetal'oxidizes with eachother. iron as itsionsaredeposited ontotheother metal. relationship Wrought earns itsnamesinceithastobeworked (or 15.Itisthese ofoxidizing castiron properties andissqueezed, andhamrolled, wrought) - dimensional retention andprotective-barrier ina workable mered while state under very - thatmadeitfeasible formation forChicago's Castironismadefrom high temperatures. Reliance toberestored after (1895) Building molten ironthatisrelatively for pure, except ofneglect, because theback-up frame for years 3 to4% carbon. approximately James Bogartheterra-cotta curtain wallwascomposed of a manufacturer of machindus, iron-grinding castiron, rather thansteel. toerect in a four-story structure ery, began 16. The current wisdom istouseeither a zinc, NewYorkin1848foruseasa factory. Ithad or urethane, epoxy corrosion-inhibiting system anexterior of cast-iron consisting only piers thesteelinorder toretard further andlintels. Russell Architec- topaint Hitchcock, Henry ture : Nineteenth andTwentieth Centuries (New corrosion. York: hadanarray ofexFig.15.TheICCPsystem Books, 1977),124. 17.Edward "Corrosion: Assessment Penguin Gerns, ontheinterior ofthebuilding. 2. Margot andRepair: TheUseofMetalWithin posedconduits Masonry Cast-Iron Architecture in Gayle, andremote-monitoring NewYork WallSystems ofEarly 9thNorth Positive, negative, Skyscrapers." DoverPublications, (NewYork: for eachofthe23zoneswascollected American Conference wiring Masonry Proceedings, 1974),viii. 2003. into boxeslikethisone.Alljunction junction Society, 3. Steel isanironthathasbeenalloyed with boxeswerecollected atthecontrol where carbon unit, 18.Thisearly atpractically attempt applying with other 0.2%and metals) allzonescanbemonitored viamodem. Photo- 2.1% (along sacrificial cathodic toprotect protection copper onthegrade ofthe by weight, depending M. graph by Novesky. hulls ofwarships wasnotentirely successful, steel. buttheconcept wassound. 4. Talbot andFunctions Hamlin, ed.,Forms of 19. Peter Corrosion inMasonry Clad installation. Institutional of Gibbs, Architecture memory , vol.4 (New Twentieth-Century 20thCentury SteelFramed , Early York: Buildings Columbia Univ. 17. If treatments is essential. a Press, 1952), building Technical Advice Note20 (Edinburgh: Historic will 5. was an be innovator of the the Jenney application building changing ownership, Scotland, 2000),60. oftheironframe andmasonry curtain wallto know-how to continue the monitoring thetalloffice TheHomeInsurance building. can be lost.Futuremasonry resystem inChicago, which he (1884-1885) Building References whohavenotbeen exhibited theessentials ofthefully pairsbycontractors designed, metal frame onitsmainfacades, madeawareofthesystem inplacecan Frederick. Construction of developed Baumann, "Improved with a curtain wall. III News . Mar. masonry 15, High Buildings." Sanitary that with easilydamage system. Finally, 1884,123. 6. Perry NewTradiDuis,Chicago Creating thechangeintechnologies comesthe H. Skeleton in William Construction Birkmire, tions Historical (Chicago: Chicago Society, continual changeincomputer . NewYork: systems. andSons, John Buildings Wiley 1976.) 1912. TheMarshallFieldICCP system is 7.Jenney hadinfact with a degree graduated "AHalfCentury Robins. oftheSkyFleming, connected to a modemwithdial-up inengineering andarchitecture from l'École CivilEngineering no.12(Dec. 4, scraper." and dial-upInternet inParisin Centrale desArts etMechanics access, capabilities 1934):634-638. T.C. BanGustav Eiffel. 1856,oneyearafter whichhavebecomeantiquated. Robins. "Whence theSkyscraper?" Fleming, Revisited PartII:TheIron nister, "Bogardus CivilEngineering 4,no.10(Oct.1934):505the ArchitecTowers," STEPHEN is of Society Journal of AIA,SE,NCARB, 509. J.KELLEY, tural Historians 1957):11with thefirm 16,no.1 (January ofWiss, Elstner AssocioftheCurtain Janney, J."TheHistory Kelley, Stephen 19. Inc.Hespecializes intheinvestigation and ates, Wall:From toMachine Craftsmanship restoration ofhistoric andmonuMade."InPreserving theRecent Past . D. buildings 8.Eugène Emmanuel Lectures Viollet-le-Duc, ments. Heisa member oftheAPTCollege of Slaton andR.Shiffer, eds.Washington, D.C.: onArchitecture Dover , vol.2 (NewYork: Fellows andispresident oftheInternational Publications, Historic Preservation Education Foundation, Inc.,1877,repr. 1987). Scientific Committee ontheAnalysis and 1995. 9.Theuseoftherigid frame inlieuofcrossRestoration ofStructures ofArchitectural Nikolaus. Pioneers Pevsner ofModern Design. to lateral stiffness was a bracing provide great at (ISCARSAH).Hecanbereached andBaltimore, Heritage Hammondsworth, England, of steel over cast even iron, advantage allowing 1974. skelley@wje.com. Books, Maryland: Penguin ofwallsintowhich windows greater expanses Nikolaus. The Sources Pevsner, ofModern couldbeplaced. Frames ofcastiron composed MATTHEW E. NOVESKY, is RA,NCARB, Architecture andDesign. London: Thames could not in moment the develop bending with thefirm ofWiss, Elstner AssociandHudson, 1986. Janney, beam-to-column a force intersect, requiring Inc.Hehassignificant with ates, P.B."Recent in experience Wight, Fireproofing Building cross-bracing. various facets ofbuilding onhisTheBritish Architect. diagnostics Chicago." May6, toric andcontemporary from Kendall Architectural investi- 10.Joseph Freitag, buildings, 1892,p.347. todeveloping andimplementing andSons, (NewYork: John gation Engineering Wiley repair Hecanbereached at 1906),9-10. designs. mnovesky@wje.com. 11.Ibid.,150. TheAPTBulletin ispublished bythe andPar"Walls, Floors, GREGORY DOWELLisanarchitectural intern 12.H. R.Dowswell, I Association ofPreservation Technolin titionstheTallBuilding" News■ ogy aninterdisciplinary with thefirm Engineering ofWiss, Elstner AssociInternational, Janney, Feb.19,1931,pp.319,321. dedicated tothepracRecord, onnumerous maIal organization BM ates, Inc.,andhasworked iNTfR nation t¡cai oftheprinciples and application facades onhistoric Hecanbe AnIntroduction 13.J.M. Richards, sonry toModern buildings. for the care andwise useof techniques necessary reached atgdowell@wje.com. Architecture (Baltimore: Books, 1962), Penguin Asubscription thebuilt environment. tothe 95. Bulletin andfree online topast access articles are Formore benefits. visit information, 14.A similar andmore familiar phenomenon, member Notes www.apti.org. iscaused twodissimilar when action, galvanic 1.Wrought ironisa two-component metal metals areincontact inwater, a providing ofhigh-purity iron(carbon content consisting This content downloaded from 128.235.251.160 on Fri, 06 Mar 2015 19:59:32 UTC All use subject to JSTOR Terms and Conditions
0
advertisement
Download
advertisement
Add this document to collection(s)
You can add this document to your study collection(s)
Sign in Available only to authorized usersAdd this document to saved
You can add this document to your saved list
Sign in Available only to authorized users