混凝土材料实验室报告英文版 Laboratory Report.docx
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混凝土材料实验室报告英文版 Laboratory Report.docx
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混凝土材料实验室报告英文版LaboratoryReport
LaboratoryReport
Introduction
Thislaboratoryreportisaboutconcretematerialsandsomenaturesofconcrete.
Concreteisthebasicengineeringmaterialusedinmostofthecivilengineeringstructures.Itspopularityasbasicbuildingmaterialinconstructionisbecauseof,itseconomyofuse,gooddurabilityandeasewithwhichitcanbemanufacturedatsite.Theabilitytomoulditintoanyshapeandsize,becauseofitsplasticityingreenstageanditssubsequenthardeningtoachievestrength,isparticularlyuseful.
Concretelikeotherengineeringmaterialsneedstobedesignedforpropertieslikestrength,durability,workabilityandcohesion.Concretemixdesignisthescienceofdecidingrelativeproportionsofingredientsofconcrete,toachievethedesiredpropertiesinthemosteconomicalway.
Withadventofhigh-risebuildingsandpre-stressedconcrete,useofhighergradesofconcreteisbecomingmorecommon.EventherevisedIS456-2000advocatesuseofhighergradeofconcreteformoresevereconditionsofexposure,fordurabilityconsiderations.Withadventofnewgenerationadmixtures,itispossibletoachievehighergradesofconcrete
withhighworkabilitylevelseconomically.Useofmineraladmixtureslikeflyash,slag,metakaolinandsilicafumehaverevolutiontheconcretetechnologybyincreasingstrengthanddurabilityofconcretebymanyfolds.Mixdesignofconcreteisbecomingmorerelevantintheabove-mentionedscenario
However,itshouldbeborneinmindthatmixdesignwhenadoptedatsiteshouldbeimplementedwithproperunderstandingandwithnecessaryprecautions.Concretemixdesignmanualisanattempttoincreasetheawarenessamongtheusers,aboutconcretemixdesign.Itismadewithintentionofservingasreadyreckonerforpersonnel,implementingmixdesignatsite.
Sieveanalysistest
Objective:
1.Finenessmodulusandgradingcurvesofsandthroughthetest,andmastersandparticlesizeoftheextentandtheparticleswiththerelationshipbetweenmasterthebasisforthejudgmentofthesandqualityisgoodorbad,theselectionofrawmaterialstoprepareforthemixingofconcrete
2.ThemainpurposeofthesieveanalysisistodeterminetheParticleSizeDistribution(PSD)ofthesand.PSDisalsoknownasGrainSizeDistribution(GSD).Thistestisperformedtodeterminethepercentageofdifferentgrainsizescontainedwithinasoil.Themechanicalorsieveanalysisisperformedtodeterminethedistributionofthecoarser,larger-sizedparticles,andthehydrometermethodisusedtodeterminethedistributionofthefinerparticles
3.Exercisessieveanalysisoperation
4.Familiarwiththeexperimentalequipment
Apparatus:
1.balanceandscale:
Thisiswhatweuseindeterminetheweightofsand,cement,aggregateandwater.Sothatweknowtheexactamountofquantityweuseinordertobeaccurateinourtest,alsothebalance(alsobalancescale,beambalanceandlaboratorybalancewasthefirstmassmeasuringinstrumentinvented.Initstraditionalform,itconsistsofapivotedhorizontalleverofequallengtharms,calledthebeam,withaweighingpan,alsocalledscale,scalepan,orbason(obsolete[),suspendedfromeacharm(whichistheoriginoftheoriginallypluralterm"scales"foraweighinginstrument).Theunknownmassisplacedinonepan,andstandardmassesareaddedtotheotherpanuntilthebeamisasclosetoequilibriumaspossible.Inprecisionbalances,aslidermassismovedalongagraduatedscale.Thesliderpositiongivesafinecorrectiontothemassvalue.Althoughabalancetechnicallycomparesweights,notmasses,theweightofanobjectisproportionaltoitsmass,andthestandardweightsusedwithbalancesareusuallylabeledinmassunits
2.Sieveswithstandardsizeof10mm,5mm,2.36mm,1.18mm,600μm,300μm&150μm.
Sieveisoneimportanttooltobeworkasafilter.EachsievehascertainspecificationsoftheholeTheuseoflargepiecesofobjectstostayinside,smallpiecesoutthroughthehole.Sothatcandistinctiondifferentsizeofsands,aggregatesandsoon.
3.MechanicalSieveShaker:
Shakertoworkistheuseofcomplexrotationvibrationgeneratedbytheoscillatorexcitation.Oscillatorrotatinghammertothescreensurfaceflatwhirlingvibration,rotatinghammertoproducetheconicalrotaryvibrationsievesurface,theeffectofthecombinedeffectsofthescreensurfacecomplexrotationvibration.Vibrationlocusisacomplexspacecurved.Thecurveinthehorizontalprojectionofacircle,anovalintheverticalplaneofprojection.Adjustment,rotaryhammerexcitationforcecanchangetheamplitude.Toadjustthephaseangleofunderthehammerspace,youcanchangethetrajectoryofthescreensurfaceshapeofthecurveandchangethetrajectoryofthescreensurfacematerial
ThisisaMechanicalSieveShaker
3.Oven
Theoven
shellisgenerallythinsteelplate,thesurfacepaint,studioqualitystructuralsteelproduction.Shellandfilledaluminumsilicatefiberbetweenthestudio.Thebottomoftheheaterinstallation,andcanalsobeplacedatthetoporsides.Thetemperaturecontrolinstrumentationwithdigitaldisplaysmarttable,PIDregulation:
Configure999.99hourstimecontrollerandthealarmdeviceisconnected.Theoperationoftheovenissimple,fastandeffective.OvenuseStainlesssteelheatpipepoweredfever,afterahighefficiencycentrifugalfansusetheairflowheatpipeheattothestudiointernal.
Inthelaboratoryweuseoventodrythesampletoaconstanttemperature(105±5)°C,toMaketheexperimentdatamoreprecise.
Procedures:
1)Weightabout500goffineaggregate.
2)Drythesamplestoconstantweightinthefurnaceatatemperatureof105˚±5˚C.
3)Measurethetotalmassoftheexampleofdryaggregate.
4)Pourthesampleofdryaggregateintothecombinationofporesizefromtoptobottomsieve.
5)Coveredthetop,placedontheMechanicalSieveShakerandkeepshakingsievefor5minutes.
6)Removethesetofsieves,weightthesampleineachsieve
7)Calculationandevaluation
Concretemixdesign
Objective:
ConcreteisthesecondlargestmaterialconsumedbyhumanbringsafterfoodandwaterasperWHO.Itisobtainedbymixingcement,fineaggregate,coarseaggregate,waterandotheradmixturesinrequiredproportions.Themixturewhenplacedinformsandallowedtocurebecomeshardlikestone.Thehardeningiscausedbychemicalactionbetweenwaterandthecementcluetowhichconcretegrowsstrongerwithage.
Thestrength,durabilityandothercharacteristicsofconcretedependupontheproportionsofitsingredients,proportionofthemix,themethodofcompactionandothercontrolsduringplacing,compactionandcuring.
Designofconcretemixesinvolvesdeterminationofthegivenconstituentsnamely,cement,water,coarseaggregateandfineaggregatewithadmixturesifany.
Factorstobeconsideredinconcretemixdesign:
1.GradeofConcrete:
Thisgivesthecharacteristicstrengthrequirementsofconcrete.Dependinguponthelevelofqualitycontrolavailableatthesite.Theconcretemixhastobedesignedforatargetmeanstrengthwhichishigherthanthecharacteristicstrength.
2.Water-CementRatio
Thecontrollingfactorformostofthedesirablepropertiesofconcrete-thingslikestrength,durability,shrinkagepotentialandpermeability-iswhat’sknowasthewater-cementratio.Itreallyisassimpleasitsounds.Justtaketheweightofwaterinacubicyardanddivideitbytheweightofcement.Durableconcretemixesusuallyneedawater-cementratioof.50orless.So,totranslate,thatwouldmeanamixwith500lbsofcementshouldn’thavemorethan250poundsofwaterorabout30gallons.
So,oneofthefirstthingswehavetodecideonewhendesigningamixisthewater-cementratio.Mixeswithlowerwater-cementratiosproducehigherqualityconcreteandtheywillusuallybebetterforthefinisherintermsofsettimes,bleedingandotherimportantcharacteristics,providedthemixalsohassufficientworkabilityforeasyplacementandconsolidation.Forspecificationwork,thiswater-cementratioisusuallydeterminedbytheservicerequirementsorconditionsfortheconcreteplacement,anditisthefirstofmanydecisionsthatrequirethemixdesignertobalanceamyriadofsometimesconflictingneeds
Water-CementRatio
3.CementandOtherPowders
Itisverycommonfortoday'smixestohavemorethanonetypeof'powder'included-inadditiontoPortlandcementmanymixeswillflyashorperhapsclagcement.Somemixesmighthaveallthree'powders'.Forpurposeofwater-cementratioyoutotalupallthepowdersanddividethatweightbytheweightofwaterinthemix.
Thetrendforthefutureseemstobetowardgreateruseofotherpowders.Whilethereareseveralreasonsforthis,includingbetterperformance,twobigreasonsarethemovetowardbuildingmaterialsthatareconsidered'green'andreductionofcosts.Theuseofoherpowdersgivesthemixdesignermoretoolsonthequesttoformulatemixesthatmeetvaryingperformancerequirements.
Bothflyashandslagproducemixesthataredenserandoftenstrongerthanplaincementmixes,andmixesutilizingmorethanonepowderareoftenmorefinisher-friendlyintermsofplacementandfinishingcharacteristic.Ofcourse,suchmixesbehavedifferentlythanplaincementmixesandgenerallyhaveslowersettimes,especiallyincoldweather.Onceagain,themixdesignerhastobalancethesefactorsasheorshemovesthroughthemixdesignprocess.
Anothertrendthatseemstobeemergingisamovebacktomixeswithhighercementitiouscontents.Therewasaperiodoftimewhen'performancemixdesign'meantthec
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