混凝土外文翻譯

外文原文二MechanicalandthermalevaluationofUltraHigh

PerformanceFiberReinforcedConcretesfOrengineering

applicationsValeriaCorinaldesi,GiacomoMoriconiDepartmentofMaterialsandEnvironmentEngineeringandPhysics,UniversitaPolitecnicadelleMarche,ViaBrecceBianche,60131Ancona,ItalyKeywords：Abstract：UltraHighPerformanceFiberReinforcedConcrete(UHPFRC)isacement-basedmaterial,whichbehaveslikealow-porosityceramicmaterialwithexcellentmechanicalperformance.Thisworkwasaimedtostudysoftcast(flowableatcastingtime)UHPFRCsand,inparticular,thetimedevelopmentofcompressivestrength,flexuralstrengthandelasticmoduluswasmonitoredforUHPFRCpreparedbyvaryingthewatertocementratiofrom0.20to0.32.Silicafume,steelfibersandacrylic-basedsuperplasticizerwereemployedtopreparetheUHPFRCmixtures.Optimumworkabilityandmechanicalperformancewereobtainedwithawatertocementratioof0.24.ThermalconductivitywasdeterminedforthesameUHPFRC,inthepresenceandintheabsenceofsteelfibers.Thescopewastoevaluatetheeffectofsteelfibersonthethermalconductivitycoefficient,inordertopredicttheUHPFRCcapacityforheatloss.Thisinformationaswellasitsdrillingcharacteristics,inordertotestitssuitabilitytobemachined,couldbeessentialforpossiblefieldsofapplicationsuchasinmechanicalengineering,whereUHPFRCmaterialscanbeemployedashighabrasion-resistantdiesinthemoldingprocessofmetalandpolymerKeywords：Machineworkability；Mechanicalperformance；UHPFRCSilicafume；Thermalconductivity1.IntroductionUltraHighPerformanceFiberReinforcedConcreteisaspecialcement-basedmaterialwhichbehaveslikealow-porosityceramicmaterialwithexcellentmechanicalperformance.Inparticular,itisasuperplasticizedsilicafumeconcrete,oftenreinforcedwithfibers,withimprovedhomogeneitybecausetraditionalaggregatesarereplacedwithveryfinesandupto400lm[1].AccordingtoRichardandCheyrezy[1],ifsoftcastandcuredatroomtemperature,itscompressivestrengthcanachieve200MPa.Infact,UHPFRCrepresentsthehighestdevelopmentofHighPerformanceConcrete(HPC)anditsultimatecompressivestrengthdependsonthecuringconditions(eitherstandardcuringorsteamcuringorautoclavecuring[2,3]),onpossiblethermaltreatments[4,5]aswellasonthemanufacturingtechniqueadopted,anditsvaluecouldriseupto800MPainthecaseofcompressivemolding[6].JusttogiveanideaoftheexcellentmechanicalperformanceofUHPFRC,thestress-straincurvesofanordinaryperformanceconcrete(OPC),ofaHighPerformanceConcrete(HPC)andofanUltraHighPerformanceFiberReinforcedConcrete(UHPFRC)areshownforcomparisoninFig.1[7].InmostindustrialcountriesHPCmaterialsarecurrentlyemployedininfrastructuralengineeringworkswhereheavystaticanddynamicstressesorsevereenvironmentalaggressionhavetobecounteracted,suchasinseaplatformsforoilextraction,longspanbridges,underseatunnels,andskyscrapersinseismicareas.However,UHPFRCmaterialsshow,althoughinanexperimentalphasewithsomefieldtests,muchhigherperformancethanHPC.Particularly,besidesextraordinarycompressiveandflexuralstrength(seeFig.1),veryhighductilityaswellastoughnessandfractureenergy[2-4]encouragesnewapplicationsforthesematerials,competingwithinnovativeceramicsandstructuralmetalsinthefieldofmechanicalandenvironmentalengineering,aswellascivilandbuildingengineering[7].ThefollowingapplicationsarepromisinginrelationtoUHPFRCmaterialsutilization[8].Inenvironmentalandchemicalengineering,highlyreliablecontainerscanbeadvantageouslyproducedtostorehazardous(toxic,inflammable,etc.)fluidsorsolids,sincetheuseofUHPFRCmaterials,inwhichnegligiblediffusionofionicandmolecularspeciesoccurs,canallowtomakeinsignificantthereleaseoftoxicorradioactivewastesfromthecontainertotheenvironment.Incivilengineering,constructionofextraordinarybuildings,whosesizesorlocationrequireveryhighperformanceintermsofbothmechanicalstrengthandductilityaswellastoughness,mayberealizedwithUHPFRCmaterials.Asamatteroffact,inTokyo,owingtoalackofavailableareas,plansofbuildingsashighas1000marebeingreliablystudied.Inmechanicalengineering,highimpact-resistantproducts,againstburstorshot,orhighabrasion-resistantdiesinthemoldingprocessofmetalproducts,suchassteelsheets,canbesuccessfullydeveloped.Actualdiesarecharacterizedbyveryhighunitcostwhich,fortheireconomicamortisation,needhighvolumeproductionlines.Thisfact,forinstance,preventssupplyflexibilityinrelationtocoachworkchangesinthecarindustry.TheuseofUHPFRCmaterials,dependingonthestrengthlevelrequirements,canallowtheproductionofcheaperprototypes,andmediumlowvolumedies.Remarkableinterestisalsoemergingintheplasticsindustryfortheproductionofdies,whoserequirementscouldbeeasilymetbyadequatelyadjustingthemixturecompositionandproportioning.ThisworkwasaimedtostudysoftcastUHPFRCs,inparticulartheirmechanicalperformance,theirthermalconductivity,inordertopredictUHPFRCcapacityforheatloss,aswellastheiradaptabilitytomachiningprocesses.Infact,aimofthispaperisalsotoinvestigatesomedrillingcharacteristicsofUHPFRCinordertoassessthecapabilityofthismaterialtobemachinedbyconventionaltools.IntermsofUHPFRCmixtureproportionoptimization,theattentionwasfocusedontheeffectofthetypeofsuperplasticizerusedandofthewatertocementratio(rangingfrom0.20to0.32)onUHPFRCperformances.InordertoreducethepriceofproducingUHPFRC,localnaturalsandwasusedasreplacementmaterialforthemoreexpensivesilicasandnormallyusedtoproduceUHPFRC,similarlywiththeattemptmadebyYangetal.[9].Generally,duetothelimitedavailableresourceandthehighcostofsilicafume,manyauthorsalsotriedtoreduceUHPFRCcostbysearchingforthesubstitutionofsilicafumebyothermaterialswithsimilarfunctionssuchasgroundgranulatedblastfurnaceslag(GGBFS)[24,10],ultrafineflyash[2,4,10],ricehuskash[11].However,inthisworktheonlymineraladditiontriedwassilicafume,besidestocement.Concerningthekindofcuring,standardcuringat20_Cwaschosen(withoutthermaltreatment),whichrepresentsthecheapestwayofproducingsoftcastUHPFRC.

r^ble1Chemi-GilwinposiiionofcemeiiLandsilicafume.Oxide俏)CemeiiLSilicarumeSiO229.5793.87MA3740.01Fg1.800.30TiQt0.090.08CaO59方0.231.15O.Gl明3250.23KjO0J90.08N仙0.00Lo-^onignition(LOL制11.60.02.MaterialsandmethodsCommercialPortland-limestoneblendedcementtypeCEMII/A-L42.5RaccordingtotheEuropeanStandardsEN-197/1[12]wasused.TheBlainefinenessofcementwas0.42m2/ganditsrelativespecificgravitywas3.05.ItschemicalcompositionisshowninTable1.Silicafumepowderwithaspecificsurfaceareaofabout18m2/g,evaluatedbymeansofBETsurfacemethod,andarelativespecificgravityof2.20wasused.ThechemicalcompositionofsilicafumeisalsoshowninTable1.Asaggregate,well-gradedveryfinenaturalsandwasusedwithparticlesizeupto100lm.Thesteelfibersusedinthisworkwere13mmlongand0.18mmthickwithanaspectratioof72,justlikethoseemployedbyRichardandCheyrezy[1].Twoacrylic-basedsuperplasticizers(labeled‘spA’and‘spB’)wereemployedinordetocomparetheireffectivenessforproducingUHPFRC.Theywerebothconstitutedofacarboxylicacrylicesterpolymerintheformof30%aqueoussolution,buttypeBisanewformulationpromisingtobemoreeffectiveinreducingwaterdosage.UHPFRCmixtureproportionsSeveralUHPFRCmixtureswerepreparedbyvaryingthewatertocementratiofrom0.20(RPC-20)to0.32(RPC-32)byusinganacrylic-basedsuperplasticizerataveryhighdosageofabout5%byweightofcementinorderthatadequateworkabilitycouldbeachieved.Thematerialswithawatertocementratioof0.24(RPC-24)and0.26(RPC-26)werepreparedbyalternativelyusingthetwotypesofacrylic-basedsuperplasticizer,inordertocomparetheireffectivenessinimprovingworkabilityataconstantwaterdosage.UHPFRCswithallotherwatertocementratioswerepreparedbyusingonlythesuperplasticizerlabeled‘spB’，whichappearedtobemoreeffectiveonthebasisofpreliminaryresults.Thecementtosandratiowas1:1(bymass)ineverycase.Foreachmixture,thedosagesofsteelfibersandsilicafumeweremaintainedequalto20%and25%byweightofcement,respectively.UHPFRCmixtureproportionsarereportedinTable2.WorkabilityofUHPFRCsatthefreshstatewasmonitoredbymeansoftheflowtableaccordingtotheproceduredescribedinEN1015-3[13]andresultsobtainedintermsofconsistencyoffreshmortarsarealsoreportedinTable2.TheRPC-20wasnotatallflowable;however,theUHPFRCworkabilitygraduallyincreasedwithhigherwatertocementratio,uptoRPC-32characterizedbyverygoodflowability.Thisattemptofcombiningexcellentmechanicalperformanceandhighworkabilitywasconductedalsobyotherauthors[14]withgoodresults.Theexpectedhighereffectivenessof‘spB’withrespectof‘spA’isconfirmedbydatagiveninTable2.PreparationandcuringofspecimensThreeprismaticspecimens(40by40by160mm)weremanufacturedforeachmixtureandforeachcuringtimeinordertoevaluatemechanicalbehaviorofthesevenUHPFRCmixtures(Table2):theyweresoftcastinsteelforms(vibratedfor30secondsaftercasting),thenwetcuredat20_C(standardcuring)forflexuralandcompressivestrengthmeasurements.Moreover,flatcircularspecimens(diameterof200mm,20mmthick)werecastandcuredinthesamewayaspreviousonesfordrillingtests(seebelow).Finally,flatcircularspecimens(diameterof200mm,30mmthick)weremanufactured,castandcuredinthesamewayaspreviousonesandsubsequentlysuitablypolished(bysandingthebases)forthermalconductivitytests.MW2UHPFRCniixmre-propcriions.RK-20RPC-為RPC25RK29RPC-32Waier/cemeiii0200.240.260.290.3201G立仲6Slumpfloworfresh1\4213139iii-orlar,露(wiJi(wiih52226(widt(WlLll.邛B'】W)MtfcEurvprapGrtions,kgperrvP-afconcreteWaler(indudii^1942272482S0洲Ll血ofsuperpUsLicker]Ceiiiem9&09S09S0960Silicafume24024024024024t>Sitelfibers192192192192192Superplasliciter(dry2424242424ITU155)S丑ixi9&09&05009&09&0-3.Resultsanddiscussion3.1.CompressiontestCompressivestrengthwasevaluatedaccordingtoEN1015-11[15]after1,3,7and28daysofcuring.Asafirststep,thecompressivestrengthofUHPFRCspreparedwithdifferenttypesofsuperplasticizerwascompared,inordertodeterminethemosteffectiveadmixture.TheresultsobtainedforUHPFRCwithw/cof0.24and0.26byusingeither‘spA’or'spB’superplasticizersaregiveninFig.2.Aslightlybetterresult,withconcerntohomogeneityandstrengthdevelopment,wasdetectedwhenthe‘spB’typewasemployedfromanearlyage.ThentheUHPFRCscontainingthe‘spB’admixturewerepreparedbyvaryingwater/cementfrom0.20to0.32.ThetimeevolutionoftheircompressivestrengthisshowninFig.3.Itcanbenoticedthatafter1dayofcuringthecompressivestrengthwasalwayshigherthan30MPa.ItisquiteevidentthatthepositiveeffectobtainedbyloweringthewatertocementratiowasnotvalidforUHPFRCswithwatertocementratiolowerthan0.24.Infact,theconcretepreparedwithw/cof0.20showedthelowestcompressivestrength.Thereasonliesinthelowcompactioncapacityofthematerialduetothepoorworkabilityofthefreshconcrete(seeTable2).Anevenhigheramountofsuperplasticizingadmixturewouldbenecessaryinthiscase.BendingtestFlexuralstrengthwasevaluatedaccordingtoEN1015-11[15]after1,3,7and28daysofcuring.Themodulusofrupture(MOR,inMPa)wasobtainedasfollows:hereListhemaximumloadapplied(N),disthedistancebetweenthesupports(100mm)andeistheedgeofthespecimen(40mm),inordertoobtainaverageinformationontheelasticbehaviorbeforefirstcracking.AscanbeobservedinFig.4,theresultsobtainedbyflexuraltestsconfirmthehighereffectivenessofthe‘spB’superplasticizerwithrespecttothatlabeled‘spA’whenawatertocementratioof0.24isadopted.Ontheotherhand,byusingthe‘spA’type,higherstrengthwasobtainedbothincompressionandbending,withaw/cof0.26insteadof0.24.Thereasoncanbeascribedtothevaluesoffreshmortarworkability(seeTable2).Infact,thebestmixtures,whateverthekindofsuperplasticizeremployed,werecharacterizedbyslumpflowvaluesintherange21-22%,whichislikelythebesttoachievehighcompactionratewhenvibrationisappliedfor30s,asinthecaseofthisexperimentalwork.ThetimeevolutionofmodulusofruptureisshowninFig.5forUHPFRCspreparedwith‘spB’admixtureandbyvaryingthewatertocementratio.Itcanbenoticedthatafter1dayofcuringthetensilestrengthwasalwayshigherthan10MPaexceptfortheUHPFRCwithwatertocementratioof0.20.Alsointhiscase,thebestmechanicalperformancewasobtainedfortheconcretepreparedwithw/cequalto0.24.Fig.2.'Timi?cvGluiiixioirianprcuiuc-Gtrc-n^h心UHfs^RRCsp^cfujcdwKhwfcni0.24arid口口&凹謳inj?由【4'spA'or!spB'如傅^陽軾記#*“.4.Timee-paljutiondt^nsiilE-stren^EhEditDHPfftCiprcfH[?iwidiwjcdFO.24ndQS6byu&in^diilw'年uVm柘例'iupcrplJSEiciatfsi卜比％Conprcssiwi卜比％ConprcssiwsUcit印thfwUHF^CspitiMrcdbyvairyinsrhcwatertDccniciitidLiufi-inLi020tu0.32aldiHin-eiifl.miiik^Liin-t^.Watr-rfC#m*ntHg?5,ModulusofruptuiTforUHPFftCspreparfdbyvarying(he-watertoccmcintidLiu-fi-inLi020Lu0.32aldifTeiitiifl.lini&.W^ter/efTHentFig,6一TimeeuoluiionofUiigenLeUsiicmodulusIbrUHPFRCspreparedbyvaryingil^ew^ieriocememr^Lk>froin0.20io032TangentelasticmodulusTangentmodulusofelasticitywasmeasuredfromthestressstraincurveobtainedincompression,atthepointofinterest,whichcorrespondstoonethirdofthecompressivestrengthofthematerial.TimedevelopmentofthetangentmodulusisgiveninFig.6forUHPFRCspreparedbyvaryingthewatertocementratioandbyaddingthe‘spB’superplasticizertothemixture.Inagreementwiththeresultsobtainedintermsofcompressiveandflexuralstrength,asiseasilyapparentthestiffestUHPFRCturnsouttobethatpreparedwithw/cequalto0.24.MachineworkabilityInordertoproduceabrasion-resistantdiesmadeofUHPFRCsomefinalmachiningoperationsareusuallyneededsuchas,typically,drilling,contouringandcutting.Theanalysisoftheseoperaoperationsisthenofprimaryimportance,becauseanydamageinducedbythisfinalstepoftheproductioncyclemightcausethediscardofthecomponentasscrap,thusfrustratingthewholemanufacturingprocess.InthisworktheattentionwasfocussedonUHPFRCdrilling.ThescopewastoevaluatethepropensityofUHPFRCtobedamagedwhendrilledorcutand,inparticular,thepresenceofdelamination,whichcanoccurbothatentryandexitsideofthehole.Thisinformationcouldbeessentialforpossiblefieldsofapplicationlikemechanicalengineering,whereUHPFRCmaterialscanbeemployedashighabrasion-resistantdiesinthemoldingprocessofmetalandpolymerproducts,suchassteelsheetsorplasticshapesasshowninFig.7.Withinthefactorswhichcanaffectthequalityofdrilling,thethrustforceplaysthemostimportantrole,leadingtooff-axismovementofthetool,holeeccentricity,poorsurfaceroughnessandtolerancesand,eventually,breakageofthetool[16].Anotherimportantissueindrillingisthetoolwear.Experimentswerecarriedoutwithtwodiameters(4and6mm)andtwofeeds-motor(0.13mmrev_1and0.34mmrev_1).Thespindlerotationalspeedwaskeptconstantat930rpm.MachineworkabilitywasinvestigatedfOrUHPFRCpreparedwithtype‘spB’superplasticizerandwatertocementratioof0.24,inthepresenceofsteelfibers.Anexampleoftheresultsobtainedwith4-mmdiameterand0.13-mmrev_1feedisshowninFigs.8aand8bwheretwopicturesarereportedoftheentranceandtheexitzoneofthetool,respectively.Thepresenceofsteelfibersoutgoingfromtheexitzone,thatpointsoutthescarcequalityofthemachining,isevident.Intheentrancemzonethisphenomenonisnearlyabsentandexclusivelyduetosomeoff-axisforces.Forholescarriedoutwithlowfeedtheexitzoneshowsasmallernumberofoutgoingfibers,and,contemporarily,theextensionofthedelaminatedareaissmaller,thusindicatingabetterqualityofthemachining.Resultsobtainedshowedthattheextentofthedelaminatedzoneisnearlyinsensitivetothetooldiameter,eventhoughtheaxialthrustforceswerehigher.Thisfactshowsthatthismaterialisverysensitivetodelamination,evenunderlowforces.Itisfinallynoticeablethatthediameteroftheentranceisalwaysgreaterthanthatoftheexit.Thisisduetoabadcenteringandtoaninsufficientguideofthetoolduringdrilling.Inordertocompensateforsuchadrawback,eitherapre-holeorachasing,orevenamaskofguide,canbeprovidedfor.Obviously,boththesemsolutionswillinvolveanincreaseofthecostsofthemachining.However,inordertoappreciatethequalityofthemachineworkability,itshouldberememberedthatUHPFRCisacementitiousmaterial.Inthislight,theresultobtainedwasveryencouragingalsobecauseitallowsforthepossibilityforeasyre-profilingofthediameterflange.ThermalconductivitytestThermalconductivitymeasurementswerecarriedoutbyusingtheguardedhotplatemethod,accordingtoUNI7745[17].Specimenswerepreviouslydriedintheovenat375390Ktoconstantweight(masslossunder1%).Theexperimentaldeviceismadeofaheatingelement(centralelementformeasuringplusanexternalguardedring),acoolingelementandexternalthermalinsulation.Thetemperaturesoftheheatingandcoolingelementsaswellasthoseofthefrontalsurfacesofthespecimenweremeasuredbymeansofthermocouples.MeasurementswerecarriedoutonspecimenspreparedwithRPC-24mixture(seeTable2),withandwithoutsteelfibers,inordertoascertaintheircontributiontotheincreaseinthermalconductivity,sincestainlesssteelhasaveryhighthermalconductivitywithrespecttoconcrete,asiswellknown.ExperimentalresultsobtainedforUHPFRCarereportedinTable3,incomparisonwiththethermalconductivitycoefficientofsteelandordinaryconcrete.Nosignificantinfluenceofsteelfiberswasapparent;however,theverylowporosityofUHPFRCwithrespecttoordinaryconcreteshowedacertaineffect(+20%)onthethermalconductivitycoefficient.LMI03Tlttnflil血ildMl沁iLiMdfOfdiilArySL-^I且MUKPFRCwith新值williOulEbers.MdierialOrdinarycaicrewSl酮UHPFRC(with貝函Fibers)UHPC(wiihouiu哽1fitwrs]Tl^nmlcortdueiiviiy(WinlK0.7816.30.940.9S4.ConclusionsUHPFRCcharacterizedbyoptimumworkabilityandmechanicalperformancewasobtainedwhenthemostrecenttypeofacrylicbasedsuperplasticizer(labeled‘spB’)andawatertocementratioof0.24wereadopted.Inparticular,28-daycompressivestrengthof156MPa,flexuralstrengthof38MPaandtangentelasticmodulusofabout90GPawereachievedfromthisUHPFRC.Fromamachineworkabilitypointofview,thedamagesustainedbyUHPFRCwhendrilledisseentobereduced,particularlyintermsofdelamination.Thisinformationispotentiallyimportantforfieldsofapplicationsuchasmechanicalengineering,whereUHPFRCmaterialscanbeemployedashighabrasion-resistantdiesinthemoldingprocess.Finally,theeffectofsteelfibersonthethermalconductivitycoefficientwasevaluatedinordertopredicttheUHPFRCcapacityforheatloss.Infact,thisinformationisalsoimportantfortheabovementionedapplicationforpolymericmaterials.Concerningthisaspect,theresultsobtainedwerenotencouragingandanothersolutionisnecessarytosolvetheproblemofheataccumulation,whichslowsdownproductivity.參考文獻RichardP,CheyrezyMH.Reactivepowderconcreteswithhighductilityand200-800MPacompressivestrength.In:MethaPKeditor.ConcreteTechnology.Past,Present,andFuture.S.Francisco,USAAmericanConcreteInstitute,ACISP144-24,1994.p.507-18.YunshengZ,WeiS,SifengL,ChujieJ,JianzhongL.PreparationofC200greenreactivepowderconcreteanditsstatic-dynamicbehaviors.CemConcrCompos2008,30(9):831-8.YaziciH,YardimciMY,Yig^iterH,AydinS,TurkelS.Mechanicalpropertiesofreactivepowderconcretecontaininghighvolumesofgroundgranulatedblastfurnaceslag.CemConcrCompos2010,32(8):639-48.YaziciH,YardimciMY,AydinS,KarabulutAS_.Mechanicalpropertiesofreactivepowderconcretecontainingmineraladmixturesunderdifferentcuringregimes.ConstrBuildMater2009,23(3):1223-31.GarasVY,KahnLF,KurtisKE.Short-termtensilecreepandshrinkageofultrahighperformanceconcrete.CemConcrCompos2010,31(3):147-52.IpekM,YilmazK,SumerM,SaribiyikM.Effectofpre-settingpressureappliedtomechanicalbehavioursofreactivepowderconcreteduringsettingphase.ConstrBuildMater2011,25(1):61-8.CollepardiM,CorinaldesiV,MonosiS,MoriconiG.DSPmaterialsapplicationsanddevelopmentprogress.In:Cerny'M,editor.CMSE/1.Procsoftheinternationalconferenceoncompositesinmaterialandstructuralengineering.Prague,CzechRepublic,2001.p.49-52.CollepardiM,CorinaldesiV,MonosiS,MoriconiG.ApplicazioniesviluppodeimaterialiDSP.L’IndustrialtalianadelCemento2002,777:540-4.YangSL,MillardSG,SoutsosMN,BarnettSJ,LeTT.Influenceofaggregateandcuringregimeonthemechanicalpropertiesofultra-highperformancefiberreinforcedconcrete(UHPFRC).ConstrBuildMater2009,23(6):2291-8.YaziciH,Yig^iterH,KarabulutAS_,BaradanB.Utilizationofflyashandgroundgranulatedblastfurnaceslagasanalternativesilicasourceinreactivepowderconcrete.Fuel2008,87(12):2401-7.VanTuanN,YeG,vanBreugelK,FraaijALA,DaiBuiD.Thestudyofusingricehuskashtoproduceultrahighperformanceconcrete.ConstrBuildMater2011,25(4):2030-5.EN-197/1,Cement-part1:composition,specificationsandconformitycriteriaforcommoncements,2000.EN1015-3,Methodsoftestformortarformasonry.Determinationofconsistenceoffreshmortar(byflowtable),1999.RossiP.Developmentofnewcementcompositematerialsforconstruction.In:DhirRK,HewlettPC,CsetenyiLJ,editors.Innovationanddevelopmentsinconcretematerialsandconstruction.London,UK:ThomasTelfordPublishing,2002.p.17-30.EN1015-11,Methodsoftestformortarformasonry.Determinationofflexuralandcompressivestrengthofhardenedmortar,1999.JahanmirS,RamuluM,KoshyP.Machiningofceramicsandcomposites.NewYork:MarcelDekker;1999.UNI7745.Materialiisolanti.Determinazionedellaconduttivitatermicaconilmetododellapiastracaldaconanellodiguardia,1977.中文翻譯二力學(xué)性能和熱性能評價超高纖維

鋼筋混凝土的工程應(yīng)用ValeriaCorinaldesi*,GiacomoMoriconiDepartmentofMaterialsandEnvironmentEngineeringandPhysics,UniversitaPolitecnicadelleMarche,ViaBrecceBianche,60131Ancona,Italy摘要：超高性能纖維混凝土（UHPFRC）是一種水泥基材料，它的行為就像一個低孔隙度的陶瓷材料，具有優(yōu)良的機械性能。這項工作是為了研究研究UHPFRC軟鑄造年代（澆筑時刻流動），特別是時代發(fā)展的壓縮強度、抗彎強度和彈性模量進行了UHPFRC準(zhǔn)備，通過改變水灰比在0.20~0.32之間。硅灰、鋼纖維和acrylic-based增塑劑用來準(zhǔn)備UHPFRC的混合物。工作性和力學(xué)性能最佳得到水灰比為0.24。導(dǎo)熱系數(shù)確定了一樣UHPFRC，存在著沒有鋼纖維。范圍的影響是評價鋼纖維導(dǎo)熱系數(shù)上，以預(yù)測UHPFRC介紹評價鋼纖維導(dǎo)熱系數(shù)上，以預(yù)測能力UHPFRC熱量損失。這它的鉆探信息特征，旨在測試的適用性加工，有可能必不可少的可能應(yīng)用領(lǐng)域如在機械工程，在那里UHPFRC材料可采用高耐磨模具成型工藝的金屬和聚合物產(chǎn)品關(guān)鍵詞：機性能；力學(xué)性能；UHPFRC；硅灰；導(dǎo)熱系數(shù)引言這項工作是為了研究研究UHPFRC軟鑄造年代（澆筑時刻流動），特別是時代發(fā)展的壓縮強度、抗彎強度和彈性模量進行了UHPFRC準(zhǔn)備，通過改變水灰比在0.20~0.32之間。硅灰、鋼纖維和acrylic-based增塑劑用來準(zhǔn)備UHPFRC的混合物。工作性和力?學(xué)性能最佳得到水灰比為0.24。導(dǎo)熱系數(shù)確定了一樣UHPFRC，存在著沒有鋼纖維。范圍的影響是評價鋼纖維導(dǎo)熱系數(shù)上，以預(yù)測UHPFRC介紹評價鋼纖維導(dǎo)熱系數(shù)上，以預(yù)測能力UHPFRC熱量損失。這它的鉆探信息特征，旨在測試的適用性加工，有可能必不可少的可能應(yīng)用領(lǐng)域如在機械工程，在那里UHPFRC材料可采用高耐磨模具成型工藝的金屬和聚合物產(chǎn)品。正文1簡介超高性能纖維混凝土是一種特殊的水泥基材料,它表現(xiàn)得像低孔隙度的陶瓷材料具有優(yōu)良的機械性能。特別是，它是一個superplasticized硅灰混凝土、鋼筋和經(jīng)常纖維，用改進后的同質(zhì)性，因為傳統(tǒng)的聚集被替換為很細(xì)砂400lm［1］。根據(jù)理查德和Cheyrezy［1］，如果軟鑄造及固化在室溫條件下，其抗壓強度可以達到200帕。事實上,UHPFRC代表的最高發(fā)展高性能混凝土(HPC)及其極限壓強度取決于固化條件(或者標(biāo)準(zhǔn)的治療或蒸汽養(yǎng)護蒸壓養(yǎng)護(2、3),熱療法可能［4、5］制造工藝上采用，其價值可能還會上升到800帕的抗壓moldi的情況。為了反映UHPFRC優(yōu)異的力學(xué)性能。UHPFRC應(yīng)力-應(yīng)變曲線的一個普通的高性能混凝土(OPC)，一個高性能混凝土(HPC)和一種極端高性能纖維混凝土(UHPFRC)被顯示出在圖1為比較［7］。大多數(shù)工業(yè)國家目前所采用高性能材料在基建工程沉重的靜和動態(tài)應(yīng)力或環(huán)境嚴(yán)重的侵略下，在幾分鐘內(nèi)被中和，如在海上采油平臺，長跨度橋梁、海底隧道，摩天大樓在地震的地區(qū)。然而，根據(jù)UHPFRC材料顯示，雖然在實驗一些野外試驗階段，高性能混凝土性能優(yōu)越得多。特別是，除了非凡的抗壓和抗折強度(見圖1)，高延性和韌性及斷裂能［2-4］，鼓勵這些材料應(yīng)用于，競爭與創(chuàng)新和結(jié)構(gòu)金屬陶瓷機械及環(huán)境領(lǐng)域的工程，以及民事、建筑工程［7］。下面的領(lǐng)域是有希望用于UHPFRC有關(guān)的材料利用［8］。在環(huán)境與化學(xué)工程。高度可靠的容器可以推進生產(chǎn)儲存危險(有毒、易燃易爆等)液體或固體，因為UHPFRC材料的使用，可以忽略離子擴散和分子種類發(fā)生變化，可以釋放有毒或放射性的廢物的從容器污染到環(huán)境。在土木工程建設(shè)、非凡的建筑，誰的大小或位置要求非常高效的性能，二者的機械強度和優(yōu)良的延性和韌性，材料UHPFRC可以實現(xiàn)。事實上，在東京，由于缺乏有效的土地，正研究計劃建造高達1000米的建筑物。在機械程、高impact-resistant產(chǎn)品，對破裂或射擊，要么在高耐磨性的成型工藝過程的金屬制品中，如鋼板表面，可以成功發(fā)展。實際模具具有很高的單位成本，經(jīng)濟攤銷，需要大量生產(chǎn)線。這個事實，例如，防止供給靈活性在汽車變化關(guān)系在世界汽車工業(yè)中。使用UHPFRC材料,根據(jù)強度等級的要求，可以允許生產(chǎn)便宜的設(shè)計原型。顯著的興趣也出現(xiàn)在了塑料工業(yè)中用于生產(chǎn)的模具，其很容易會被充分地調(diào)整混合料組成及比例。這項工作是研究旨在探討鑄造UHPFRCs，具體的目標(biāo)是他們的力學(xué)性能、導(dǎo)熱率，及為了預(yù)測UHPFRC的容量熱損失，以及他們對加工過程的適應(yīng)性。事實上，本論文的目的也是研究UHPFRC的一些的特點，通過傳統(tǒng)的加工工具評估這種材料的能力。為了UHPFRC摻混比例優(yōu)化、關(guān)注主要對影響超塑化劑的類型使用和水灰比（范圍從0.20到0.32）UHPFRC表現(xiàn)。為了降低生產(chǎn)UHPFRC的價格，當(dāng)?shù)厣a(chǎn)的天然砂作為替代材料，較昂貴的硅砂通常用來生產(chǎn)UHPFRC,，同樣的嘗試，用于楊等人。[9]。一般來說，由于有限資源和高成本的硅灰，許多作者也試圖降低UHPFRC的成本，尋找替代硅灰和其他材料相似地面砂等功（GGBFS）[2-4、10],超細(xì)粉煤灰（2、4、10],[11]稻草殼灰。而在這部作品中除了對水泥，只有礦產(chǎn)硅灰的嘗試。關(guān)于這種固化，最便宜的方式是標(biāo)準(zhǔn)養(yǎng)護選擇在20C（沒有熱處理）投入的UHPFRC生產(chǎn)。OUHPFRCL^ble1Chemi-ulcomposiiionofcem-eni血1idsil記afume.Oxide俏）CeinentSilicifuine296798.87aijo33740.011.800.30TiQt0.090.08CaO59250.231.150.G1昭3250.2330790.08Ng0.2B0.00Lassonignition11.60.02材料和方法商業(yè)Portland-limestoneII型混合水泥量42.5R/A-L潤澤歐洲標(biāo)準(zhǔn)使用EN-197/1[12]。布萊尼的細(xì)度對水泥為0.42平方米/g和相對比重為3.05。其化學(xué)作文是顯示在表1。硅灰粉與一個特定的表面面積約18平方米/g、評估打賭表面的方式方法,一個相對比重2.20被使用。這硅灰的化學(xué)成分也顯示在表1。作為骨料、well-graded很細(xì)采用天然沙粒徑到100年的激光束。鋼纖維用于這項工作13毫米長,0.18毫米厚的與一個設(shè)計了一組寬高比為72,就像那些受雇于理查德和Cheyrezy[1]兩個acrylic-basedsuperplasticizers（標(biāo)記的水療'和'spB”）被雇用來以比較其生產(chǎn)UHPFRC有效性。他們倆都構(gòu)成羧酸酯的丙烯酸聚合物的水溶液形式的30%，但是是一種有前途的新配方能更有效地減少水用量。2.1UHPFRC混合比例以UHPFRC混合物為原料，制備了通過改變水灰比的影響（RPC-20）從0.20到0.32（RPC-32）用一個acrylic-based高效減水劑在一個非常高劑量的重量大約5%的水泥，為了使足夠的工作性也做不成。一個水材料的水泥比率為0.24（RPC-24）和0.26（RPC-26凝膠或者使用這兩種類型的acrylic-based高效減水劑，以比較它們的有效性以一個恒定的性能改善水的用量。UHPFRCs所有其他水灰比進行了只使用高效減水劑貼上“spB'，顯得更加有效的基礎(chǔ)上,初步的結(jié)果。水泥沙比1:1（質(zhì)量）在所有的情況。為每一個混合物，鋼纖維用量和硅灰維持等于20%和25%水泥的重量。UHPFRC混合比例報告表2。UHPFRCs性能在流動狀態(tài)監(jiān)測的方法根據(jù)流程表描述的過程在EN1015-3[13]的結(jié)果根據(jù)混凝土的一致性的流動也報道在表2。這RPC-20根本不流動，然而，UHPFRC和易性逐漸增加水灰比高，具有RPC-32非常良好的流動性。這種努力相結(jié)合的力學(xué)性能優(yōu)良和高和易性也進行了其他作者[14]有很好的效果。期望更高的有效性方面的spB'和’spA的確認(rèn)數(shù)據(jù)所給的表2。2.2準(zhǔn)備和固化的試樣柱狀試件（4040-160毫米）是專為每一個并為每個混合物固化時間為了評價的力學(xué)行為七UHPFRC混合物（表2）。他們趕在鋼軟形式（振動鑄造成型后30秒），然后再20°C下濕固化（標(biāo)準(zhǔn)養(yǎng)護）為彎曲及抗壓強度的測量。此外，先前為鉆井試驗，扁圓形標(biāo)本（直徑200毫米,20毫米厚）被澆筑和固化了同樣的測試見下文）。最后，扁圓形標(biāo)本（直徑200毫米,30毫米厚）制造、鑄鐵和固化在同樣的方式，先前隨后適當(dāng)拋光（砂的基地）導(dǎo)熱系數(shù)測試。表2UHPFRC混臺比例/混合物U2盼2#2部29+J3眼水冰泥A0.20^0.24+J0.26+J0.29^0.32^水」粘含劑0.16^0.19+J0.26^砂漿P2忡3忡39+^_jl.Iq混合比例,應(yīng)方米的混凝土水〔包括高城喊水劑】1卯248230306+J水泥960^60960PVW?,?960ww?,?960+J?.??.??.?5硅灰的24024024024024->銅纖維1921921321921瀝高魏兆水劑〔干重）2424W-?.24..???????.24沙960960960560960+J3結(jié)果和討論3.1壓縮試驗根據(jù)抗壓強度評價EN1015-11[15]后1、3、7和28天內(nèi)固化。作為第一步,UHPFRCs的抗壓強度的準(zhǔn)備與不同類型的高效減水劑相比較，決定最有效的組合。所得結(jié)果為UHPFRC以w/c0.24和0.26采用兩的“spA”或“spB的superplasticizers給出了圖2。稍微更好的結(jié)果，與均勻性和強度關(guān)系，，檢測當(dāng)"spB”型應(yīng)從早期采用。然后UHPFRCs含有“spB的外加劑分子篩通過改變水/水泥在0.20到0.32之間波動。時間隨著他們的抗壓強度的變化。如圖3。它可以注意到經(jīng)過1天固化的抗壓強度總是高于30帕。顯而易見，通過降低了水灰比是不適用UHPFRCs的，在低于0.24水灰比的時候的影響。事實上，w/戒混凝土準(zhǔn)備0.20顯示出最低的壓應(yīng)力力。原因在于它的壓實力低資料由于劣等的流動混凝土和易性（見表2）。一個更高的數(shù)量的superplasticizing外加劑在這種情況下是必要的3.2彎曲試驗根據(jù)抗彎強度是評價EN1015-11[15]在第1、3、7和28天內(nèi)固化。模量對破裂（MOR,MPa）得到如下：可以觀察圖4中，彎曲，得到了令人滿意的結(jié)果.試的有效性確認(rèn)更高的spB的高效減水劑對這個標(biāo)記的spA的水灰比的影響0.24已被采納。另一方面，利用“spA的類型、更高無論是在壓縮強度得到和彎曲，w/c為0.26，而不是0.24。原因可以歸結(jié)于值流動的砂漿和易性（見表2）。事實上，最好的混合物，無論采用什么樣的超塑化劑，進行表征流動的價值暴跌21-22%的范圍內(nèi)，這是可能的最好的，在這個實驗工作的情況以實現(xiàn)高振動壓實率應(yīng)用30秒，。模量的時間演化的破裂是顯示在圖5UHPFRCs準(zhǔn)備的spB的摻合料，通過改變水水泥的比例。它可以發(fā)現(xiàn)經(jīng)過10天固化的抗拉強度總是高于10theUHPFRCMPa除水灰比為0.20。在這種情況下，最好的力學(xué)性能得到了具體的。3.3切線彈性模量進行了測量切線彈性模量拉力應(yīng)變壓縮曲線，從曲線上得到。其對應(yīng)于三分之一的抗壓強度材料。代的發(fā)展的切線模量了圖6UHPFRCs準(zhǔn)備通過改變水灰比的影響增加“spB的超塑化劑的混合物。壓應(yīng)力和抗彎強獲得的結(jié)果與前面一致的，明顯UHPFRC的是準(zhǔn)備以w/c等于0.24。3.4機械性能為了產(chǎn)生UHPFRC的主要一些最后的加工操作，通常壓模是需要的，如一般,鉆井、造型和切割。對這些操作然后最重要的，因為任何傷害誘導(dǎo)這最后一步的生產(chǎn)周期可能引起棄牌組件作為廢鐵，從而挫敗了整個制造過程。在這工作的注意力都集中在UHPFRC的開采。這范圍的傾向是評價UHPFRC被損壞當(dāng)被鉆孔或減少，尤其是分層的存在，能夠既發(fā)生在出入境一側(cè)的洞。這所包含的信息可能是至關(guān)重要的應(yīng)用領(lǐng)域可能喜歡機械工程專業(yè)，在那里UHPFRC材料能被使用高耐磨模具成型工藝金屬、聚合物產(chǎn)品，如鋼板表面或塑料的形狀如圖7。在影響質(zhì)量因素鉆井驅(qū)動力起著至關(guān)重要的作用，導(dǎo)致軸運動的工具，孔偏心，可憐的表面粗糙度和公差，并最終破碎的工具[16]。另一個重要的問題是鉆井刀具磨損。進行了試驗研究和兩個直徑（4和6毫米）和兩個feeds-motor（0.13毫米rev1和0.34毫米rev1）。這主軸轉(zhuǎn)速為930轉(zhuǎn)/分是保持不變。研究了機械性能UH