毕业设计外文参考资料及译文.docx

毕业设计外文参考资料及译文.docx

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毕业设计外文参考资料及译文

外文参考资料

Mechanicalpropertiesofperviouscementconcrete

CHENYu1,WANGKe-Jin2,LIANGDi1

1.SchoolofTrafficandTransportationEngineering,

ChangshaUniversityofScienceandTechnology,Changsha410004,China;

2.DepartmentofCivil,ConstructionandEnvironmentalEngineering,IowaStateUniversity,Ames,IA50010,USA©CentralSouthUniversityPressandSpringer-VerlagBerlinHeidelberg2012

Abstract:

Compressiveandflexuralstrength,fractureenergy,aswellasfatiguepropertyofperviouscementconcretewitheithersupplementarycementitiousmaterials（SCMs）orpolymerintensified,wereanalyzed.TestresultsshowthatthestrengthdevelopmentofSCM-modifiedperviousconcrete（SPC）differsfromthatofpolymer-intensifiedperviousconcrete（PPC）,andporosityhaslittleeffectontheirstrengthgrowth.PPChashigherflexuralstrengthandremarkablyhigherflexural-to-compressivestrengthratiothanSPCatthesameporositylevel.Resultsfromfracturetestofperviousconcretemixeswithporosityaround19.5%showthatthefractureenergyincreaseswithincreasingthedosageofpolymer,reflectingtheductiledamagefeaturesratherthanbrittleness.PPCdisplaysfarlongerfatiguelifethanSPCforanygivenfailureprobabilityandatanystresslevel.Itisprovedthattwo-parameterWeibullprobabilityfunctiondescribestheflexuralfatigueofperviousconcrete.

Keywords:

perviousconcrete;strength;fracture;fatiguelife

1Introduction

Perviouscementconcretewasaconcretewithcontinuousvoidsthatwereintentionallyincorporatedintoconcretebyblendingwithnoorverylittleamountoffineaggregates.Cementitiousmaterialswerenotenoughtofillthevoidsamongcoarseaggregateswithspecialparticle-sizedistributiontomakeinterconnectedmacropores[1−2].Therangeofporositythatwascommonlyreportedforperviousconcreteutilizedinpavement,wasabout15%−25%[3−4].

Thesignificantlyreducedstrengthofconventionalperviousconcreteduetohighporosity,notonlylimiteditsapplicationinheavytrafficroadsbutalsoinfluencedthestabilityanddurabilityofthestructures,becauseof,forexample,susceptibilitytofrostdamageandlowresistancetochemicals.However,byusingappropriatelyselectedaggregates,silicafume（SF）ororganicintensifiers,andbyadjustingconcretemixingproportion,themechanicalpropertiesofperviousconcretecouldbeimprovedgreatly[5−6].YANGandJIANG[7]showedthattheuseofSFandsuperplasticizer（SP）inperviousconcretecouldobviouslyenhanceitsstrength.TheresultsalsoindicatedthatSFhadabettereffectforimprovingthepropertiesofperviousconcretethanpolymerwhenusingwithSP;anditcouldobtaincompressivestrengthof50MPaandflexuralstrengthof6MPa.KEVERN[8]presentedthattheadditionofpolymer（styrenebutadienerubber）inperviousconcreteimproveditsworkability,strength,permeabilityandfreeze-thawresistance,resultinginhigherstrengthatrelativelylowercementcontentsandhigherporosity.

Fundamentalinformation,includingtheeffectsofporosity,water-to-cementratio,cementpastecharacteristic,volumefractionofcoarseaggregates,sizeofcoarseaggregatesonperviousconcretestrength,hadbeenstudied[3,9−12].However,forthereasonthattheporosityplayedakeyroleinthefunctionalandstructuralperformancesofperviousconcretes[13−14],therewasstillaneedtounderstandmoreaboutthemechanicalresponsesofperviousconcretesproportionedfordesiredlevelsofporosities.

Althoughitwaspossibletohavewidelydifferentporestructurefeaturesforagivenporosity,orsimilarporestructurefeaturesforvariedporositiesinperviousconcrete,itwasimperativetofocusonthemechanicalresponsesofperviousconcreteatdifferentdesignedporosities.However,comparedwiththerelatedresearchonconventionalconcrete,verylimitedstudyhadbeenconductedonthefractureandfatiguebehaviorsofperviousconcrete,whichwereespeciallyimportantforpavementconcretesubjectedtoheavytrafficandtosevereseasonaltemperaturechange.

Thepresentedworkoutlinedtherawmaterialsandmixingproportionstoproducehigh-strengthsupplementarycementitiousmaterial（SCM）modifiedperviousconcrete（SPC）andpolymer-intensifiedperviousconcrete（PPC）atdifferentporositieswithintherangeof15%−25%.Then,themechanicalpropertiesofperviousconcrete,includingthecompressiveandflexuralstrengths,fractureenergy,aswellasfatigueproperty,wereinvestigatedindetails.

2Experimentprogram

2.1Rawmaterialsandmixingproportions

TypeIOrdinaryPortlandCement（OPC,withthedetailsinTable1）andgraniteaggregateswereusedforallperviousconcretemixtures.Thecombinedaggregates,4.75mmand9.5mmparticleswerechosentopreparethemixtures.TocastSPC,flyash（typeC,FA）,SFandSPwereused;whileSJ-601,themixtureofvinylacetateethylenecopolymer（VAE）andacrylicemulsion,wasaddedtoproducePPC.Table2liststhemainpropertiesofSJ-601.

TwoseriesoftestingspecimenswerecastinaccordancewiththedesignatedmixingproportionspresentedinTable3,inwhichψindicatesthemassratioofaggregatein1m3concretetotheloosedensityafterbeingdenselyvibrated.ThepercentagesofFAandSFwerethereplacementsofthesamemassofOPC;whilethoseofSPandSJ-601weretheadditionaldosages.Itshouldbeclarifiedthattoomuchpolymerblockedthevalidporesandbadlyinfluencedthepermeabilityofperviousconcrete.SJ-601dosagemorethan12%wasnotrecommended[1,6].

2.2Testmethods

ThestrengthtestswerecarriedoutaccordingtoGT/B50081—2002（StandardforTestMethodofMechanicalPropertiesinOrdinaryConcrete）.

Straingaugeswerestickatthemid-pointonthebottomsurfaceofbeamspecimen（150mm×150mm×550mm）,whichsustainedtwo-thirdssymmetricalloadingF.ThecorrespondingstrainξwasmeasuredbyX−Ydigitalrecorder.ξwasthentranslatedinto,whichmeantthemid-spandeflectionofbeamspecimeninaccordancewithEq.

（1）.So,theenvelopedareabyF−▽curveandX-axiswasdefinedasW,fractureenergyofconcrete,whichcouldbecalculatedbyEq.

（2）[15−16]:

（1）

（2）

Where▽isthedynamicdeflectionofthemid-spanbeam;LandHarethespanandheightofbeamspecimen,respectively.ξisthestrainvaluemeasuredatthemidpointofbeambottom,whileareferstothehorizontaldistancefromtheloadingpointtothesupportabutments.

MTS-810TESTSTAR,anelectro-hydraulicservo-typematerialtestingmachine,wasservedtomeasuretheflexuralfatiguelifeofperviousconcrete.Threestresslevelsofsinewaveloading（0.90,0.80and0.70）with0.1ofcyclingeigenvalue,10Hzoffrequencyandzerotimegap,wereadopted.Thenumberofthecyclicloadthatthetestedspecimensweresubjecteduntilfailurewasrecorded.

Table1PropertiesofOPC

Chemicalcompositions/%

Strengthat3d/MPa

Strengthat28d/MPa

SiO2Al2O3CaOMgOFe2O3SO3K2O

CompressiveFlexural

CompressiveFlexural

22.15.162.51.54.22.90.4

27.75.4

53.78.1

Table2PropertiesofSJ-601

Solidcontent/Viscosity/pHDensity/

RatioofstrengthwithtowithoutSJ-601

%（Pa·s）（g·mL-1）

CompressionBendingTensionCohesion

47±30.03﹣0.0451.08±0.03

＞0.91.21.21.5

Table3Mixingproportionsofperviousconcrete

ΨPorosity/

SPC

PPC

%

Water-to-binderratioFA/%SF/%SP/%

Water-to-cementratioSJ-601/%

0.90﹣0.9815﹣25

0.28﹣0.3412﹣186﹣100.3﹣0.8

0.30﹣0.348﹣12

3Resultsanddiscussion

3.1Strength

Thecompressivestrengthsofallmixesareexpressedasapercentageoftheir28dstrengthandshowninFig.1.NoevidenteffectofporosityonthestrengthdevelopmentforbothSPCandPPCisobserved,thatis,perviousconcretesatdifferentporositiesfollowthesamestrengthgrowthprocess.ThestrengthdevelopmentofSPCisobviouslyrapidatearlyageswithmorethan50%at3dand80%at7d;whilethefurtherincrementsareonly5.6%at56dand8.9%at90donaverage,respectively（Fig.1（a））.Immediatelyaftercementpasteishardened,whichisacceleratedbySFandSP,aggregatesarewrappedandcementedtogethertoformtheskeleton-porestructure,obtainingquitestrongabilitytoresistdestructiveload.However,duetomuchlargerquantityofaggregatesinperviousconcretecomparedtothatinconventionalconcrete,itisreasonablethatthereisnoremarkablestrengthincreasingatlaterages.

Figure1（b）showsthatthecompressivestrengthofPPCisshortof50%at7dandreachesonlyabout70%at14d,whichquitelagsbehindthestrengthdevelopmentofSPC.Cementhydrationandpolymerfilm-formingprocesstakeplaceatthesametime.Itistimeconsumingforcementhydrationproductsandorganicfilmstointertwine,tointerpenetrateandtobuildupthenetworkstructureofpaste,firmlywrappingandbindingaggregateparticlestogether.Therefore,PPCobtainsacceleratedstrengthimprovingatlaterages,i.e.upto117%at90donaverage.ItisworthnotingthatbecausethereisacontradictionbetweencementhydrationandSJ-601polymerization,itisbeneficialforPPCtobewetcuredatleast3dtoensurecontinuoushydrationofcement,andthentobestoredatadryenvironmentwithrelativehumiditylessthan70%forbetterformingofPolymer.

SeenfromTable4,PPChashigher28dflexuralstrengthsandremarkablyhigherflexural-to-compressivestrengthratiosthanSPCatthesameporositylevel.SJ-601intensifiesperviousconcretebyformingstronglycohesivefilmattheinterfacialtransitionzone（ITZ）betweenaggregatesandhardenedpaste,andbyfillingthemicroporeswithinconcrete.Itmakespreviousconcretelessbrittleandhavestrongerresistancetoflex