外文翻译.docx
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外文翻译.docx
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外文翻译
毕业设计外文资料翻译
题目烟台科技学院办公楼设计
学院泉城学院
专业土木工程
班级土木09Q1
学生秦小碗
学号20093023117
指导教师林明强
二〇一三年五月二十七日
Cement&ConcreteComposites32(2010)718–725
Effectofrice-huskashondurabilityofcementitiousmaterials
GemmaRodríguezdeSensale
UniversityofMinnesota,Minneapolis,USA
abstract
InthispapertheeffectsofpartialreplacementsofPortlandcementbyrice-huskash(RHA)onthedurabilityofconventionalandhighperformancecementitiousmaterialsareinvestigated.DifferentpercentagesofRHAreplacementlevels,twoRHAs(amorphousandpartiallycrystallineoptimizedbydry-milling)andseveralwater–cementitiousmaterialsratioarestudied。
Thefollowingdurabilityaspectsweretested:
airpermeability,chlorideionpenetration,alkali-silicaexpansion,sulfateandacidresistance.TheresultswerecomparedwiththoseofcementitiousmaterialswithoutRHA.ItisconcludedfromthetestedpropertiesthattheincorporationofbothRHAsinconcretesshowdifferentbehaviorsforairpermeabilityandchlorideionpenetrationdependingonthewater/cementitiousmaterialsratioused;Inmortars,itreducesthemasslossofspecimensexposedtohydrochloricacidsolutionanddecreasestheexpansionduetosulfateattackandthealkali-silicareaction.TheresultsofdurabilityaspectsduetophysicalorpozzolaniceffectsaftertheadditionofbothRHAs,anditschemicalcomposition,ingeneralindicateanenhancedperformance,provingthefeasibilityofitsrationalutilizationasasupplementarycementingmaterial.
Keywords:
Rice-huskashWasteutilizationDurability
1、Introduction
TheFoodandAgricultureOrganization’sforecastofglobalriceproductionoverthe2009seasonwas678milliontonnes,about20%ofwhichisricehuskwhichistypicallyawastematerialfromthepointviewpointofindustrialandagriculturalprocesses.Evenafteritsincineration,20%ofricehusk’sweightremainsasawastematerialintheformofrice-huskash(RHA).
Asanexample,inUruguay,wherericeproductionhashadadramaticincreaseoverthepasttenyears(becomingthemostimportantcropsince2001),themainuseofricehuskisasfuelinthericepaddymillingprocess。
Buttheuseofthisfuelgeneratesahugevolumeofashwhichhasnoimmediateusefulapplicationandisusuallydumpedintowaterstreamscausingpollutionandcontaminationofsprings.Asaresult,theuseofRHAhasarousedgreatinterest.
ThechemicalcompositionofRHAdependsontemperatureandburningtime,butthevariationsinthecomponentsarenotsignificant.Theashfromopen-fieldburning(orfromnon-controlledcombustioninindustrialfurnaces)usuallycontainsahigherproportionofnon-reactivesilicamineralssuchascristobaliteandtridymite,anditshouldbegroundintoveryfineparticlestodeveloppozzolanicactivity.Inaddition,highlypozzolanicashcanbeproducedbymeansofcontrolledcombustionwhensilicaiskeptinnon-crystallineform.Suchsilicacanreactwhenaddedtocementinthepresenceofwater(withcalciumhydroxide)resultingincementitiouscompounds.Mostresearchconfirmsthefactthatburningtemperatureisacriticalpointintheproductionofamorphousreactiveash.
ThispaperpresentsastudyoftheinfluenceofbothRHAsindurabilitypropertieswithdifferentwater/(cement+RHA),materialsratiosandreplacementsofcementbyRHA.TheresultsarecomparedwiththoseofcementitiousmaterialswithoutRHA.
2.Experimentalprogram
2.1.Materials
Thefollowingmaterialswereusedinthepreparationofthespecimens:
aPortlandcementtypeI(normalPortlandcement);naturalsiliceousriversandwithmaximumaggregatesizeof4.75mm;coarseaggregate(crushedgranite)withmaximumaggregatesizeof12.5mm;andasulfonatednaphthaleneformaldehydecondensatebasedsuperplasticizer(solidscontent42%).TwosourcesofRHAwereconsidered:
aresidualRHAproducedinparboilingprocesswithburningtemperaturenoteffectivelycontrolled(fromtheonlyfactoryofparboiledriceinUruguay);andahomogeneousashproducedbycontrolledincinerationfromtheUnitedStates(CRHA).TheresidualRHAusedinthisresearchwasaprocessedwastewhichwasdry-milledforthenecessarytimetoobtainamedianparticlesizeof8um,adefinedspecificsurfacebynitrogenabsorption,andthemaximumactivityindexaccordingtoASTMC311-98b.TheprocedureforresidualRHAoptimizationispresentedinpreviousresearch.TheoptimizedresidualRHAisnamedasRRHA.Bothashes,RRHAandCRHA,arethesameasusedin.
ThephysicalandchemicalcharacteristicsofPortlandcementandthetwoashesaregiveninTable1.ChemicalanalysesindicatethatbothashesaremainlycomposedofSiO2.Bothasheshavethesamemedianparticlesizeandactivityindex.X-raydiffraction(Fig.1)indicatesthatCRHAcanbeconsideredasanamorphousRHA;butRRHAshowedcrystallinestructures,whichwereidentifiedascristobalite.ArapidSincethepercentageofreactivesilicacontainedinCRHAwas98.5%,andinresidualRRHAwas39.55%,RRHAcanbeconsideredpartiallycrystalline.analyticalmethodforevaluatingamorphoussilicainRHA(accordingtoPayaetal.)hasbeenused.
2.2、Experimentaldetails
ForstudyingtheeffectsofRHAondurabilityofcementitiousmaterials,concretesandmortarsweremade.Theinvestigateddurabilityaspectsofthehardenedconcretewereairpermeabilityandchlorideionpenetration.Alkali-silicaexpansion,acidandsulfateattackinmortarspecimensarealsostudiedinthiswork.InordertoassesstheeffectofRHAonconcretedurability,water–cementitiousmaterialsratioof0.50,0.40and0.32wereselectedtocharacterizenormalandhighperformanceconcrete.Basedonpreviousresearch,concretemixeswith5%,10%and15%ofcementreplacementbyRHAwerestudiedinthisinvestigation.ConcretemixeswithRRHA,CRHAandcontrolPortlandcementconcretemixes,withoutRHA,weremade.Table2showsthemixtureproportionsinweightofthematerials.Concretewasmixedinaconcretemixerfor3min.Theslumptestwasimmediatelyperformedafter
thematerialwasblended.ThevaluesobtainedaresummarizedinTable2,wheresuperplasticizerpercentagesareusedinrelationtoweightof(cement+RHA).Superplasticizerwasusedinverylowpercentages,accordingtotheresultsobtainedintheslumps,toallowconsistencyadjustmentswithoutchangingtheproportionoftheothermaterials(tryingtomakethechangeinsuperplasticizercontentintheconcreteswithRHAassmallaspossible).
AccordingtoTable2,CRHAconcreterequiresmoresuperplasticizerthatRRHAconcrete;thisisbecauselossonignitionthatRRHA,asshowninTable1,andthereforehigherunburntcarboncontent.Unburntcarbonhasverylargesurfacearea,andwaterdemandishigher,soCRHAneedshighersuperplasticizerdosageforagivenlevelofworkability.Forconcretes,threetestspecimenswerepreparedforeachtype
ofanalyzedvariable.AllthespecimenswerecastfollowingthedirectionsoftheMercosurCode(calledNM);then,theywerelabeledandcuredinmoldsfor24h.Afterwards,theyweredemoldedandcuredaccordingtothetestmethodusedforeachdurabilityaspectstudied.
Formortars,fivespecimenswerepreparedforeachtypeofanalyzedvariableaccordingtothetestmethodused.Mortarsforthestudyofacidandsulfateattacksweremadewithanaggregatefine-cementitiousmaterialsratioof2.75,water–cementitiousmaterialsratioof0.50,0.40and0.32,and0%,5%,10%and15%ofcementreplacementbyRHA;forthealkali-silicareaction(ASR),accordingtoASTM1260–01,awater–cementitiousmaterialsratioof0.47wasused(detailswillbepresentedlater).MortarswithRRHA,CRHAandwithoutRHAwerestudy.TheflowwasmeasuredaccordingtoASTMC109,andsuperplasticizerwasusedtoachievethesameflowasthereferencemixturewithoutRHA.
3.Testresultsanddiscussion
3.1.Airpermeability
TheresultsofthetestsforconcreteswithandwithoutRHAaregiveninTable3,whereKtrepresentsgaspermeability,qelectricalresistance,andtheconcretequalityclassisdeterminedfromKtandinanomogramaccordingtheSwissStandardSIA1:
2003.
Forwater–cementitiousmaterialsratioof0.50,theresultsofairpermeabilitywithoutRHAarehigherthanthosewithRRHA,andtheconcretequalityobtainedisnormal;withCRHA,theresultsofairpermeabilityarebetterthanthosewithoutRHA,andtheconcretequalityobtainedisgood.
Forhighperformanceconcretewithwater/cementitiousmaterialsratioof0.32and0.40,theconcretequalityclassresultsforRHAconcreteandcontrolconcretewithoutRHAdonotdifferonetoanother,botharegood;butforwater/cementitiousratioof0.32with10%and15%,CRHAresultsarebetter(verygood).
TheairpermeabilityresultsshowabetterairpermeabilityfortheCRHAthanfortheRRHAconcretes.ThisismainlyduetothepozzolaniceffectofCRHA,whichproducesadecreaseinthetotalporosityattributedtothechangeoccurringinporesizedistribution(beingaconsequenceofthefactthatCRHAcouldreactwithcalciumhydroxidetoformCSH).
3.2.Chlorideionpenetration
Table4showstheresultsforCl_depthofpenetrationandthediffusioncoefficient(D)byimmersioninwater,havingaCl_concentrationequalto5%for21days.Theresultsshowdifferentbehaviorsdependingonthewater/cementitiousmaterialsratio.
behaviorsdependingonthewater/cementitiousmaterialsratio.ItcanbeseenthattheCl_depthofpenetrationandthediffusioncoefficientinconcreteswithwater/cementitiousmaterialsratio
of0.50decreaseswithbothRHAs;thebestresultsareobtainedwith15%CRHA.
4、Concludingremarks
Thispaperanalyzesaspectsofdurabilityofcementitiousmaterialswithoutrice-h
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