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SPETIIICATION

SOMETIPSONHOWTO CHOOSE

i: i-l,rtrf l-; l - '-i:.:;ver thepastdecade.imestoncs avebecome neofthe mostpopularchoicesof stone or many applications, arlicularlyin residential ork I think t is thesoft.wann colourofmanylimestoneshatappealso designers ndpulchasers like

Along the way, however, here havebeen a fetv challenges Thcschave typically occurred whcn a limestone tvas selected for ap.ojcct without tlle decision makcrs necessarily eing ully awarcof the likely perfbrmance of this limestone in the proposedapplicatlon.What do I mean by this' l Well . n most cases,f thcdesrgner norvs hat this beautifulcream imestone hat he hasjustbeer shownby thestonesupplier will tunr brown in placeswithirtwo monthsof it being ald on the shower w4lls of the apartmentshe is designing. hen i t is l ike ly that he would keep ookingbecarrse e doesn'tneeda claim againsthis profcssional ndennityinsulance. nd sirn i lar ly.f the designer nows hat he attractivebandedimestonehatshehasjust electediom thccatalogue i l lturngreenwith in six monthsol insta l lat ion s external laddingbecause he high porosity results n dte stone staying wct most ofthc tirne and algaegrowing on it. thcn she \.vouldprobably keeplook iDs l so .In thc pre\ ous ss e of Di.tcoret ng Stotle issue#6). PeterHartogand Pcter lcKenzie discussedomcof theproblems hatcan bcencounicfed \ ith l i estone- n part icular he stalDing hat canarise forn alkaLne ohtions.

used can influence thc outcome.A useful rcferencebr selectionof dimensronstone or an) p.ojectis ASTM C1528-02 Sttuulanl Guide fot Selectiotl(t Dinen.ti.rlStone br Erteriu Utie.

FOR YOUR NEXT PROJEcapitalise on the poprlarity of limestone. Incidentaily, thegeologists tell us that true marbles are only those stones thaidisplay consistent development of crystalline calcite with noevidence of the lbssll origrn remaining Stones ike the CarraE(from ltaly) and Chillagoe (tiom northern Queelsland) marblesare exarnplesThis range of material known as limestone means hat there arematerials suitable for all applications, rom massiveashlarwallconstruction, hrough o thin veneer or externalcladdingoi high-rrse bulldlngs; and liom bathroom vanity tops, to gardensculptu les.Picking the Proprties to Proyide PerforrnanceOlle of the challenges or most designers s understanding ow tlephysical propertiesof a stonewill lead to acceptable edormancein use Thele rs someguldanceavailable,but unfoftLrnately hereareso manydrffcrent stones vailable oday,and the stone ndustNis so competitive, hat the industryas a whole has been unable ofund the research required to provrde clearer definition ofacceptable performance levels. Unfortunately, the consensusprocess involved in developneit of the ASTM StandardSpeclfications refered to above)means hat he limits on physicalproperties.contained n lhese standards,can only be used as ageneralgu1de, ather han as an absolutevalue.ASTM C568 classifieshmestones n three categories asedon tleb r r l lden . i r lo f t he rm e \ loner . o l l ow .

Class I I (High-density) Limestonewith densitygreater ha D2560 kg/rn3The fequirements1br physical propefiies for each of these hreeclassesarc siven rn Table I of ASTM C568-03 as ollorvs:

Therc are \a\s to reduce he likelihoodof problems. uch as Class (Low density) Lirnestone vith densltybetween1760these. occurrins \ irh l imestone nsla l lar ions- hcsc lnclucle 2160kg/m3detailing and iD stallation teasures.Horrcrer. th is anicle is Class I (Medlum-density) Llmestonewith densitybetweenfbcused n how thcorig inalchoiceof the lpe of l i esroneo be 2160 2560kg/m3

What is a limestone?The geologistsdescribe imestonesas rocks formcdliom the fbssilsof mannc creatures. hese ocks canrangc om recently aid downsediments,uchas heMouDt Gambter limestone (ffom SA). which has avery lorv bulk dcnsrty and high lvater absor?tron(>20%).and s sofi enlougho be cut wtth a handsawif necessary; through to highly metamotphosedstones.such as the Cotnblanchien rmestolre 1lomFrance)usedat Darling Park in Sydncy,which has ahigh density and low water absorptron

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SPII AT N

Howeve., the importanceof thesephysical propertiesdependsontheproposeduse of the imestone.The following table (Table 2) gives some common applicahons,the key physical properties,and some ndicahve values or thesephysrcalpropefties hatwould representmaterial ikeLy o performwell in the typical application,dependent, owever,on the methodof installation, panel size and particular local environmentalconditions.

Note that theseare indicative values. t is sometlmespossible omodify thedesigndetaihngofan installation o as o successfully selimestoneswith propefiiesoutside hese anges.Fufihermote,evenlimestoneswith propefiiesconfoming to these ecorrmendationsmay not pertbm satisfactorily f other parameters such as thepresence f deleteriousmineralsor weakveins)existPetrographicDescriptions ellUs MoreWhen we look at a stone,we see he colour, we see eatures, uchas veins and fossils and ilclusions. We also see a range ofpossibilities,dependingon who we are and what we are ookng atthe stone or What we cannot see, normally, is what causes hestone o be what it is.This is where petrographicdesc ptions (or petrography)can anddo tell us more By taking a thin sliceof the stone,and inspectingit under a high powered microscopewith specia l l ight ingconditions, experienced geologists known as petrographersareable to identify the minerals which form the basic coistituents ofall stones They are able to determine he approximatequantityofeach mineral, and even fface some of the formative history of thestone.This is important because t can distingulsh between ronminerals hat are unstablewhen exposed o the weatheror alkalinesolutions, which will then discolour the stone, and those ironmlnerals hat arenow stable,but which long ago changedstateandare responsible or the brown colour of the stone.Petrographicdescriptionsof limestone can distinguish betweencalcitic and dolomitic limestones the lafter tend to be harder

fi "*" r*^.""s,one.onr issue 7\) a-

wearing Petrographicdescriptionscan identify the prcsenceofswellingclays n stylolites,which can ead imestoneso breakapanin wet or damp conditions Petrographic escriptions an detect hepresence f unhealed eaJsn the abric of the imestone, vhich arelikely to be the cause of weaknessesn the stone.Petrographlcdescriptions an also dentify thepresence f a whole rangeof otherminerals hat might causeproblemsafter nstallationof the stone.What petrographicdescriptionscannot do is provide an absoluteassurance f quality, or of how a limestone will perfbm in use Agood petrographerwill find many small featureshidden in thestructure and compositiotl of a llmestone, and whilst thepetrographermay be able to link some or all of these eatures opossibleproblems n use, his will not be a catego cal conclusion.Rather, rt will provide a set of pointersfor closerexamilation ofthe stone n use elsewhere o see f these eaturesdo actually eadto problems n use.Inspectionof Installations or Learning rom Others)Ove. the years, the industry has consistently leamt about theproblems with particular stones through reviewing theirperfbrmance n use. Much of this knorvledge s anecdotaltarisesfrom persollal experience.However, there is much to be gainedfrom utilising this approach during the process of choosing alimestone or a currentproject.lnspection of installationsof the limestone under consideratiotrcan help confirm:. rts ability to withstand the tbot traffic or environmentalconditions t is subJectedo. any possibledete oration due to thepresence f deleteriousminerals,weak veins or other rruneralogical eatures. the range n appearance ttributable o colour, fossils, veins,texture,etc,. the way it weaN or weathersunder natural conditions.This inspectioncan help confirm the suitability, or otherwise,any pafticular limestone for the project and application beingconsldered.Appearance is in the Eye of the BeholderOne of the hardestaspects f deliveringa quality stone nstallatiotris managing he appearance fthe stone. fyou want to get t ghlthere s a simple secret:understand he natural angeofcolour andtexture n the stone,and what causes t Work with this variation.and ensure hat the designer,quarrier, abricator and installer allshare he sameunderstanding f the requled outcome

This means hat the designercannotrely on that 100 mm squaresamplehe found at the back of thesample lbrary in theoffice, andexpect hat every panel n the 2000 squaremetre nstallationon hislatestproJects all identical o that.Equally, t means hat he stonesupplier canlot expect to give the client three idenhcal 300 mmsquare tiles as range samples, and then supply tiles for thebathroomsof 150 apartmentsn a kaleidoscopicarray of shadesand tonalities.No, what it means s that theremustbe a conversation etween hedesigner and the supplier about what the real range of thislimestone or this project would be. This rangewill dependon:. geologicalorigins (massivelybedded imestoneswith limitedmetamorphicactivity tend o be more consistent n colour andtexturecomparedwith those hat are n more stratified depositsand/or have beensubject o greatermetamorphicheat and/orpressure) T

E

Application Physical ploperiy ValueExternal ladding Fle{ura trenothC8B0mi n B mDaV{ater bsorDtionC97 max 2./.Internalwall in inq F exurastrenqth, 880,m n 5 mpaExternalmasonrywalling,Drotected v eaves lQqlnpressve strenqth,C170,min 5 mp aWaterabsorpton C97,max 30%External aving Compressrvekenoth, 170.m n 80 moaAbras n resistance 1353.mi n 15 (TabedWaterabsorptlon,C97,max 20/"Internalllooring,commercial

Comoressivetrenoth 170mi n B0moaAbrasionesistance,1353m n 15 taber)WaterabsorptionC97 max 2./.S ip resistance HlohStain esistance HiohInternal looring,residential(notwetareas)

qompress estrenclth,l70, min 60 moaAbrasionesistance 1353mi n 10 iaber)Waterabsorpton C97 rnaxSl p resstance rderateStan resstance HighInternallooring,residentialWet teas- bathrooms, ools)

lomoressivekenothC170 mrn 60 mDaAbrasionesstance, l353,m n l0 (Tabef)WaterabsorptionC97 maxSlip esistance HighStain esistance ntqnResidentialounte.tops(balhroom, itchen)

FleNUraltrenoth, BBomi n B mpaWater bsorot n.C97.max 2%Sta res tance High

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Tuirlsr:r CrifC" - l ' r - .iJJl rJ :3JJll- '_l UJ J.J )ytVll.rliri,r.rr:

- i r :gc i B t i .ADI (Industrial Diamond Application)is a world-wide leader in thediamond tool manufacturing fieldfor stoneoceramic, glassrnechanics and optical industries.

Exclusive gent:GDKStonepty LtdMelbourne: 03)9SS3 0gs

Sydney: 02)95190971Brisbane: 071 200,1686Perth:(08)924935gg

email:enquiries@cdkstone.com,auweblwww.cdkstone,com,au

SPt0l tA l0N. s izc ol thc uni ls (casier o control 00 mm tiles than 1500I200 mrr panels)' direction t' s labbingper.pcndicularo beciding ay be bandecl.but ikely to have cssvariattonn shrdingovcral l :whefeas,paral le l o beddingmay be clouded- nd n some ilnestones-couldhavedarker Dd ighterslabs). rcquired in ish honed ndpoiishedin ishes howgreater veral lcoiourvariatio0 hansa\rr or other ext l l rcd iu ishes). character ist icsf the imestone fossi ls. e ins, tylo l i tes. installationareits lotsof small areas uchas bathroollts. itchcn:or l if t iobbies) anaccommodatea.iation crosshe cntireploJectalthough ot at the ndtv icLuallement tagelwhcreas,nextcrnal {gade equircshat hevariat io l l e managed crossvery arge lcahr rny experience,hcre s nothjngbct tcr han akiig the cl icnithrough he process f understrndinghc amouDt f val i i l t ion ha :ls inherent n the limcstone hat is Ltndcr onsidefati(Dor thipro jcct .This lnighl mcan ookingat othcr pfqects \\,herc t ha:beeu nstal ledaiwaysa good dca ilr a numbefof reasous), l l :mlgnt mean settrngup a mock-lp or fange sample \vith isisnif icartuumberof pancls f stone aken l-onl everal i f teretr .qualry blocks cpresentinghe rangc (]1colour and appearanc.lrkely o beencounteredrring sUpplybr theprojectA signif icannunbef mightbc 7-10 full s izeslabs, r 20 ,10 ut o sizepanel,The former is ahvayseasicr, nd is of assistancen helping .understlnd he fcatures incLusioDs.eins.bands. ossi ls th uextsL n thesk)ncFrom these.a sct of samplcsshould be agrccdby the cl icr(desrgner) and the sup plier (tabricator) (lefini0g thc ke,chtracfer ist icsnot. just olour. ut a lso cxtu leaud eaturcs th eare acceptableor the projectat hand Thcre mighr be Lhrec grer-"samples. lrt $,ould eneIal lyook br f ive br mostmarenals n"Drorcl therc respecif icssues cquir.edo be cousideredsucha.l i rn i tat ions n thesire.quant i lyanddensity t ' bssi ls)In somc cases, he r-augc electionprocessnight lead to a.alternat ivcnaler ia l eing onsidereduc o an unacceptableaur-oi lar iat ion n thcof ig in l l preten d Inaterial. r j t miqht ead o -chi lnqc n he e\ ' he intcstones qoing u bc L lsed n thepro- iecio Lhlt heVtLratto|] a ln c accommodele(ln a manner cceptabtrr he dcsisnet :Sumrnan'So. r conclLr, i ioI.he i)ur kcy issucs o considcr vhen hoosin-r ltme\tonL'or lndccd. ny othet ypeof sfonelar e[ . Phlsicalptopertieso ensure ropcrperfinmNliceI Petrographiccscr ipt ioDo teduccunknowu isks: . J r -pc . i n , r . r , r t , on .. , : l r J r r e c -n rn rc r rucr r r . e,+ Ranse samplesb cnsureagrcedappcaranceI recomrrencl hat designcrs nd stone suppl ic lsput ir ]crcase-r igour anclcl fbrt into consideringhesc bur issucsduring tf :selection l l imesbne for an-\i foJect I bclieve that sLlchapprolch nevitably esults n less vasted inte.energyand co .incufcd throughdisputcsover thc stonesllpp]iedor problenwith its pcfbrnlance n useDdt'il We\t is o Drrcttor ol th(' ,\ sttolidn St(ne Alt,is/,Assacia l ionHt hdt iten \ \ ' (dt.se\p?titt tLI in the te\t ing ut:erdludtionoJ itiu ^ion stone bt us? n huildincs He is u ncnh,of ASTM CotnnitteeCl6 on lincnsiott stnn?,Luut t:o neullinralred ut tlt itiitidl leralolrnent o/ AS/M Cl52S @