混凝土外文翻译

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-为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&凹讴inj?由【4'spA'or!spB'如傅^阳轼记#*“.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贝函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.参考文献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.中文翻译二力学性能和热性能评价超高纤维

钢筋混凝土的工程应用ValeriaCorinaldesi*,GiacomoMoriconiDepartmentofMaterialsandEnvironmentEngineeringandPhysics,UniversitaPolitecnicadelleMarche,ViaBrecceBianche,60131Ancona,Italy摘要：超高性能纤维混凝土（UHPFRC）是一种水泥基材料，它的行为就像一个低孔隙度的陶瓷材料，具有优良的机械性能。这项工作是为了研究研究UHPFRC软铸造年代（浇筑时刻流动），特别是时代发展的压缩强度、抗弯强度和弹性模量进行了UHPFRC准备，通过改变水灰比在0.20~0.32之间。硅灰、钢纤维和acrylic-based增塑剂用来准备UHPFRC的混合物。工作性和力学性能最佳得到水灰比为0.24。导热系数确定了一样UHPFRC，存在着没有钢纤维。范围的影响是评价钢纤维导热系数上，以预测UHPFRC介绍评价钢纤维导热系数上，以预测能力UHPFRC热量损失。这它的钻探信息特征，旨在测试的适用性加工，有可能必不可少的可能应用领域如在机械工程，在那里UHPFRC材料可采用高耐磨模具成型工艺的金属和聚合物产品关键词：机性能；力学性能；UHPFRC；硅灰；导热系数引言这项工作是为了研究研究UHPFRC软铸造年代（浇筑时刻流动），特别是时代发展的压缩强度、抗弯强度和弹性模量进行了UHPFRC准备，通过改变水灰比在0.20~0.32之间。硅灰、钢纤维和acrylic-based增塑剂用来准备UHPFRC的混合物。工作性和力•学性能最佳得到水灰比为0.24。导热系数确定了一样UHPFRC，存在着没有钢纤维。范围的影响是评价钢纤维导热系数上，以预测UHPFRC介绍评价钢纤维导热系数上，以预测能力UHPFRC热量损失。这它的钻探信息特征，旨在测试的适用性加工，有可能必不可少的可能应用领域如在机械工程，在那里UHPFRC材料可采用高耐磨模具成型工艺的金属和聚合物产品。正文1简介超高性能纤维混凝土是一种特殊的水泥基材料,它表现得像低孔隙度的陶瓷材料具有优良的机械性能。特别是，它是一个superplasticized硅灰混凝土、钢筋和经常纤维，用改进后的同质性，因为传统的聚集被替换为很细砂400lm［1］。根据理查德和Cheyrezy［1］，如果软铸造及固化在室温条件下，其抗压强度可以达到200帕。事实上,UHPFRC代表的最高发展高性能混凝土(HPC)及其极限压强度取决于固化条件(或者标准的治疗或蒸汽养护蒸压养护(2、3),热疗法可能［4、5］制造工艺上采用，其价值可能还会上升到800帕的抗压moldi的情况。为了反映UHPFRC优异的力学性能。UHPFRC应力-应变曲线的一个普通的高性能混凝土(OPC)，一个高性能混凝土(HPC)和一种极端高性能纤维混凝土(UHPFRC)被显示出在图1为比较［7］。大多数工业国家目前所采用高性能材料在基建工程沉重的静和动态应力或环境严重的侵略下，在几分钟内被中和，如在海上采油平台，长跨度桥梁、海底隧道，摩天大楼在地震的地区。然而，根据UHPFRC材料显示，虽然在实验一些野外试验阶段，高性能混凝土性能优越得多。特别是，除了非凡的抗压和抗折强度(见图1)，高延性和韧性及断裂能［2-4］，鼓励这些材料应用于，竞争与创新和结构金属陶瓷机械及环境领域的工程，以及民事、建筑工程［7］。下面的领域是有希望用于UHPFRC有关的材料利用［8］。在环境与化学工程。高度可靠的容器可以推进生产储存危险(有毒、易燃易爆等)液体或固体，因为UHPFRC材料的使用，可以忽略离子扩散和分子种类发生变化，可以释放有毒或放射性的废物的从容器污染到环境。在土木工程建设、非凡的建筑，谁的大小或位置要求非常高效的性能，二者的机械强度和优良的延性和韧性，材料UHPFRC可以实现。事实上，在东京，由于缺乏有效的土地，正研究计划建造高达1000米的建筑物。在机械程、高impact-resistant产品，对破裂或射击，要么在高耐磨性的成型工艺过程的金属制品中，如钢板表面，可以成功发展。实际模具具有很高的单位成本，经济摊销，需要大量生产线。这个事实，例如，防止供给灵活性在汽车变化关系在世界汽车工业中。使用UHPFRC材料,根据强度等级的要求，可以允许生产便宜的设计原型。显著的兴趣也出现在了塑料工业中用于生产的模具，其很容易会被充分地调整混合料组成及比例。这项工作是研究旨在探讨铸造UHPFRCs，具体的目标是他们的力学性能、导热率，及为了预测UHPFRC的容量热损失，以及他们对加工过程的适应性。事实上，本论文的目的也是研究UHPFRC的一些的特点，通过传统的加工工具评估这种材料的能力。为了UHPFRC掺混比例优化、关注主要对影响超塑化剂的类型使用和水灰比（范围从0.20到0.32）UHPFRC表现。为了降低生产UHPFRC的价格，当地生产的天然砂作为替代材料，较昂贵的硅砂通常用来生产UHPFRC,，同样的尝试，用于杨等人。[9]。一般来说，由于有限资源和高成本的硅灰，许多作者也试图降低UHPFRC的成本，寻找替代硅灰和其他材料相似地面砂等功（GGBFS）[2-4、10],超细粉煤灰（2、4、10],[11]稻草壳灰。而在这部作品中除了对水泥，只有矿产硅灰的尝试。关于这种固化，最便宜的方式是标准养护选择在20C（没有热处理）投入的UHPFRC生产。OUHPFRCL^ble1Chemi-ulcomposiiionofcem-eni血1idsil记afume.Oxide俏）CeinentSilicifuine296798.87aijo33740.011.800.30TiQt0.090.08CaO59250.231.150.G1昭3250.2330790.08Ng0.2B0.00Lassonignition11.60.02材料和方法商业Portland-limestoneII型混合水泥量42.5R/A-L润泽欧洲标准使用EN-197/1[12]。布莱尼的细度对水泥为0.42平方米/g和相对比重为3.05。其化学作文是显示在表1。硅灰粉与一个特定的表面面积约18平方米/g、评估打赌表面的方式方法,一个相对比重2.20被使用。这硅灰的化学成分也显示在表1。作为骨料、well-graded很细采用天然沙粒径到100年的激光束。钢纤维用于这项工作13毫米长,0.18毫米厚的与一个设计了一组宽高比为72,就像那些受雇于理查德和Cheyrezy[1]两个acrylic-basedsuperplasticizers（标记的水疗'和'spB”）被雇用来以比较其生产UHPFRC有效性。他们俩都构成羧酸酯的丙烯酸聚合物的水溶液形式的30%，但是是一种有前途的新配方能更有效地减少水用量。2.1UHPFRC混合比例以UHPFRC混合物为原料，制备了通过改变水灰比的影响（RPC-20）从0.20到0.32（RPC-32）用一个acrylic-based高效减水剂在一个非常高剂量的重量大约5%的水泥，为了使足够的工作性也做不成。一个水材料的水泥比率为0.24（RPC-24）和0.26（RPC-26凝胶或者使用这两种类型的acrylic-based高效减水剂，以比较它们的有效性以一个恒定的性能改善水的用量。UHPFRCs所有其他水灰比进行了只使用高效减水剂贴上“spB'，显得更加有效的基础上,初步的结果。水泥沙比1:1（质量）在所有的情况。为每一个混合物，钢纤维用量和硅灰维持等于20%和25%水泥的重量。UHPFRC混合比例报告表2。UHPFRCs性能在流动状态监测的方法根据流程表描述的过程在EN1015-3[13]的结果根据混凝土的一致性的流动也报道在表2。这RPC-20根本不流动，然而，UHPFRC和易性逐渐增加水灰比高，具有RPC-32非常良好的流动性。这种努力相结合的力学性能优良和高和易性也进行了其他作者[14]有很好的效果。期望更高的有效性方面的spB'和’spA的确认数据所给的表2。2.2准备和固化的试样柱状试件（4040-160毫米）是专为每一个并为每个混合物固化时间为了评价的力学行为七UHPFRC混合物（表2）。他们赶在钢软形式（振动铸造成型后30秒），然后再20°C下湿固化（标准养护）为弯曲及抗压强度的测量。此外，先前为钻井试验，扁圆形标本（直径200毫米,20毫米厚）被浇筑和固化了同样的测试见下文）。最后，扁圆形标本（直径200毫米,30毫米厚）制造、铸铁和固化在同样的方式，先前随后适当抛光（砂的基地）导热系数测试。表2UHPFRC混台比例/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」粘含剂0.16^0.19+J0.26^砂浆P2忡3忡39+^_jl.Iq混合比例,应方米的混凝土水〔包括高城喊水剂】1卯248230306+J水泥960^60960PVW・,・960ww・,・960+J・.・・.・・.・5硅灰的24024024024024->铜纤维1921921321921沥高魏兆水剂〔干重）2424W-・.24..•・・•・・•.24沙960960960560960+J3结果和讨论3.1压缩试验根据抗压强度评价EN1015-11[15]后1、3、7和28天内固化。作为第一步,UHPFRCs的抗压强度的准备与不同类型的高效减水剂相比较，决定最有效的组合。所得结果为UHPFRC以w/c0.24和0.26采用两的“spA”或“spB的superplasticizers给出了图2。稍微更好的结果，与均匀性和强度关系，，检测当"spB”型应从早期采用。然后UHPFRCs含有“spB的外加剂分子筛通过改变水/水泥在0.20到0.32之间波动。时间随着他们的抗压强度的变化。如图3。它可以注意到经过1天固化的抗压强度总是高于30帕。显而易见，通过降低了水灰比是不适用UHPFRCs的，在低于0.24水灰比的时候的影响。事实上，w/戒混凝土准备0.20显示出最低的压应力力。原因在于它的压实力低资料由于劣等的流动混凝土和易性（见表2）。一个更高的数量的superplasticizing外加剂在这种情况下是必要的3.2弯曲试验根据抗弯强度是评价EN1015-11[15]在第1、3、7和28天内固化。模量对破裂（MOR,MPa）得到如下：可以观察图4中，弯曲，得到了令人满意的结果.试的有效性确认更高的spB的高效减水剂对这个标记的spA的水灰比的影响0.24已被采纳。另一方面，利用“spA的类型、更高无论是在压缩强度得到和弯曲，w/c为0.26，而不是0.24。原因可以归结于值流动的砂浆和易性（见表2）。事实上，最好的混合物，无论采用什么样的超塑化剂，进行表征流动的价值暴跌21-22%的范围内，这是可能的最好的，在这个实验工作的情况以实现高振动压实率应用30秒，。模量的时间演化的破裂是显示在图5UHPFRCs准备的spB的掺合料，通过改变水水泥的比例。它可以发现经过10天固化的抗拉强度总是高于10theUHPFRCMPa除水灰比为0.20。在这种情况下，最好的力学性能得到了具体的。3.3切线弹性模量进行了测量切线弹性模量拉力应变压缩曲线，从曲线上得到。其对应于三分之一的抗压强度材料。代的发展的切线模量了图6UHPFRCs准备通过改变水灰比的影响增加“spB的超塑化剂的混合物。压应力和抗弯强获得的结果与前面一致的，明显UHPFRC的是准备以w/c等于0.24。3.4机械性能为了产生UHPFRC的主要一些最后的加工操作，通常压模是需要的，如一般,钻井、造型和切割。对这些操作然后最重要的，因为任何伤害诱导这最后一步的生产周期可能引起弃牌组件作为废铁，从而挫败了整个制造过程。在这工作的注意力都集中在UHPFRC的开采。这范围的倾向是评价UHPFRC被损坏当被钻孔或减少，尤其是分层的存在，能够既发生在出入境一侧的洞。这所包含的信息可能是至关重要的应用领域可能喜欢机械工程专业，在那里UHPFRC材料能被使用高耐磨模具成型工艺金属、聚合物产品，如钢板表面或塑料的形状如图7。在影响质量因素钻井驱动力起着至关重要的作用，导致轴运动的工具，孔偏心，可怜的表面粗糙度和公差，并最终破碎的工具[16]。另一个重要的问题是钻井刀具磨损。进行了试验研究和两个直径（4和6毫米）和两个feeds-motor（0.13毫米rev1和0.34毫米rev1）。这主轴转速为930转/分是保持不变。研究了机械性能UH