Standard Practice for Shotcrete喷射混凝土的标准做法 3

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StandardPracticeforShotcrete喷射混凝土的标准做法3

EM1110-2-200531Jan93andanyotherindicationsofeithermixtureproportionproblemsornozzlemanworkmanship.7-3.ProductionPhaseAnongoingprogramoftestingshouldbeperformedbytheContractortoverifythatthematerials,methods,andin-placeshotcretemeettherequirementsofthecontractdocuments.Thespecificationsshouldclearlystatetheminimumtypesofteststhatarerequired,theminimumfrequencyofperformingeachtest,aprocedureforreportingtheresultsofthetests,andaprocedureforcorrectinganydeficiencies(Table7-1).a.Materials.(1)Cementitiousmaterials.Manufacturerscertifiedtestresultsforthecement,pozzolan,andappropriatetestdataforsilicafumeshouldbefurnishedattheintervalspecifiedandwheneverachangeintheappearanceorperformanceofthematerialissuspected.(2)Aggregates.(a)Quality.Testdatashouldbefurnishedtoverifythatthequalityoftheaggregatesmeetstherequirementsofthespecifications.Testdatashouldbesubmittedatestablishedintervalsandwheneverachangeintheappearanceorperformanceofthematerialissuspected.(b)Grading.ThegradingofeachaggregategroupshouldbeverifiedbytestingaccordingtoCRD-C103(ASTMC136)atestablishedintervalsandwheneverachangeintheappearanceorperformanceofthematerialissuspected.Changesinthegradingofanaggregatewillcauseachangeinthewaterrequirementsofthemixturewithattendantchangesinthestrengthandplacingcharacteristicsoftheshotcrete.(c)Moisturecontent.Themoisturecontentofeachaggregategroupmustbeknowntocalculatetheamountoffreewatertobeaddedtoeachbatchofshotcrete.Themoisturecontentsshouldbeestablishedpriortostartofeachshiftandwheneverachangeismadeinstockpilesources.(3)Admixturesandcuringcompound.Manufacturerscertificatesofcompliancefortheair-entrainingadmixture,retardingadmixture,water-reducingadmixture,acceleratingadmixture,andcuringcompoundshouldbefurnishedatanestablishedintervalandwheneverachangeintheappearanceorperformanceofthematerialissuspected.b.Surfacepreparation.TheContractorsabilitytopreparesurfacesaccordingtotherequirementsofthespecificationsshouldbeverifiedduringeachshift.Noshotcreteshouldbeplaceduntilsurfacepreparationsarecompleted.Bondingoftheshotcretelayertotheunderlyingstratumisessentialforproperperformanceandlongevity.c.Shotcrete.(1)Strength.Thestrengthoftheshotcreteshouldbeverifiedatestablishedintervals.Themethodofobtainingsamples,themethodoftesting,thefrequencyoftesting,andtherequiredstrengthshouldbeclearlystatedinthecontractspecifications.(a)Testpanels.Atestpanelshouldbeshotatleastonceashift.Thepanelshouldbeshotbyanozzlemanwhoisplacingshotcreteinpermanentworkshotcrete.Thepanelshouldbeatleast18by18by3inches.Thetestpanelshouldbecuredattheprojectsiteinaccordancewiththecontractrequirementsuntilithasattainedsufficientstrengthtoallowmovementtothetestinglaboratory.Curingshouldcontinueinthetestlaboratoryuntilspecimensareobtainedfromthepanel.CoresorbeamsshouldbetakenfromthepanelinaccordancewiththeprovisionsofCRD-C27(ASTMC42).Coresareusedtoverifythecompressivestrengthofnonfiberreinforcedshotcrete,andbeamsareusedtoverifytheflexuralstrengthoffiber-reinforcedshotcrete.(b)In-placesamples.AtestablishedintervalsandwheneverdeemednecessarybytheContractingOfficer,coresorbeamsshouldbeobtainedfromthein-placeshotcretetoverifythestrength.Thesamplesshouldbecuredandtestedinamannersimilartothatoftestpanelsamples.(2)Mixtureproportions.Themixtureproportionsoftheshotcreteshouldbecheckedregularlytoverifythattheoriginalproportionsarebeingmaintained.Thisisgenerallyaccomplishedbyverifyingthatthebatchweights,especiallythecementitiousmaterialsandwaterweights,areasrequired.(3)Aircontent.Wet-mixshotcreteisgenerallyrequiredtohaveaspecifiedaircontentasdeterminedbyCRD-C41(ASTMC231).Theaircontentshouldbedeterminedatregularintervalsandatlocationsasspecified.Theaircontentspecifiedinthecontractdocumentsishigherthanrequiredfordurableconventionalconcreteandallowsforabout50percentof7-2EM1110-2-200531Jan937-3EM1110-2-200531Jan93theairtobelostduringthedeliveryandshootingoftheshotcrete.Thespecificationmustdetailhowaircontentistobedetermined.Ifsampledatthepump,thetestisperformedasdetailedinCRD-C41(ASTMC231).(4)In-placethickness.Gaugewiresorstudsshouldbesetpriortoplacingshotcretetofacilitateplacingoftherequiredthickness.Itisbesttoverifythicknessbymeasuringtheoffsetofthegaugewiressincelaterprobingofthein-placeshotcretemaybeverydifficult.Thein-placethicknessoftheshotcretemaybeverifiedbyprobingthefreshshotcretewithasharptool.Thinareasshouldbecorrectedbyimmediateapplicationofadditionalmaterial.CoresofhardenedshotcretemaybedirectedtobetakenbytheContractingOfficertoverifyareasofsuspectthickness.(5)Reboundtesting.Itisadvantageoustoperiodicallydeterminetheamountofshotcretethatisreboundingfromtheplacementsurfaces.Thiscanbedonebydesignatingaplacementareaandcollectingallthereboundmaterialaftertheplacementiscomplete.Thepercentofreboundcanbecalculatedbydeterminingthevolumeofmaterialshotandthevolumeofmaterialcollected.(6)Curingandprotection.Thecontractorshouldverifythattherequiredcuringandprotectionoftheshotcreteisbeingfurnished.Propercuringisimportantduetothegenerallylowwatercontentofshotcrete.Anyprematuredryingcouldimpairthehydrationprocess.Properprotectionduringhotorcoldweatherisessentialtoproperhydrationofshotcrete.(7)Nondestructivetesting.Theuniformityandqualityofin-placeshotcretemaybeassessedbynondestructivetestingdevicessuchasimpacthammersorprobes(CRD-C22(ASTMC805)andCRD-C59(ASTMC803)),ultrasonicequipment(CRD-C51(ASTMC597)),andpulloutdevices(CRD-C78(ASTMC900)).TheuseofsuchdevicesshouldbeatthedirectionoftheContractingOfficerandshouldbeusedtoidentifyareasofsuspectqualityandrelativestrength,notforactualstrengthdetermination.(8)Delaminationtesting.Whereappropriate,completeshotcretecoatingsshouldbecheckedforcompletebondtothesubstrateandbondbetweeneachshotcretelayer.Thiscanbedoneusingasmallhammeronthesurface.Thecontractshouldrequirethatalldelaminatedareasberemovedandshotcretereapplied.(9)Surfacetolerances.Someapplicationsmayrequirethatexactingsurfacevariationtolerancesbemet.Verifyingthatasurfacemeetsatoleranceisbestdoneusingthespecifiedlengthstraight-edgeandmeasuringthegapbelowtheedge.Thespecificationshouldbeclearthatthismethodwillbetheverificationmethod.(10)Visualinspection.Thequalityoftheshotcreteshouldbethoroughlyevaluatedbyvisualinspection.Surfacesshouldbeinspectedforuniformity,voidsatthesurfaces,varyingfinishconditions,dryconditions,seepageofwater,cracking,anddamagedsections.7-4.CorrectiveActionsWhenasubmittalortestreportindicatesthatamaterialorproductfailstomeetthecontractrequirements,thecorrectiveactionsspecifiedinthecontractdocumentsshouldbeinitiatedimmediately.7-4EM1110-2-200531Jan93Chapter8QualityAssurance8-1.GeneralConsiderationsa.QualityAssurance(QA)activitiesonashotcreteprojectshouldbedirectedtoobtainingcompliancewiththecontractrequirements.Thequalityofthematerialsusedintheproductionoftheshotcreteandofthein-placeshotcreteareestablishedduringthedesignstageoftheprojectandshouldhavebeenclearlystatedinthecontractdocuments.b.AmemorandumentitledEngineeringConsiderationsandInstructionsforFieldPersonnelshouldbepreparedbythedesignerinaccordancewithEM1110-2-2000.Thismemorandumoutlinesthedesignersintentandhighlightstheareasofspecialconcernduringconstruction.Ifanydoubtsexistbyconstructionpersonnelastotherequiredquality,theyshouldberesolvedwiththedesignerasearlyintheprojectaspossible.c.QualifiedQApersonnelwithpreviousexperienceonshotcreteprojectsshouldbeassignedtotheproject.ER1180-1-6shouldbefollowedinpreparingaQAPlan.Thefollowingdiscussionspertaintotechnicalaspectsofshotcreteandshouldbeincorporatedintotheplan.8-2.PreproductionPhasea.Submittals.Priortostartofproductionofshotcreteforanypermanentwork,therequiredmaterial,equipment,andproceduralsubmittalsshouldbereviewedbytheappropriateCorpsofEngineersrepresentativestoverifycompliancewiththecontractrequirements.Onlargerprojects,governmentverificationofcementitiousmaterialspropertiesshouldbeconsidered.b.Mixtureproportioningevaluation.TestpanelsshottoverifytheproposedmixtureperformanceshouldbevisuallyexaminedbyQApersonneltoconfirmuniformityoftheshotcrete.Specimensshouldbetakenfromthetestpanelstoverifythatthespecifiedstrengthisbeingattained.ThespecimensmaybetakenbyeitherQCorQApersonnel,butstrengthtestingshouldbeperformedbyaCorpsofEngineersdivisionlaboratoryortheprojectlaboratory.c.Nozzlemancertification.AllnozzlemenshallbeACIcertified.TestpanelsshottoevaluateanozzlemansqualificationsshouldbethoroughlyexaminedbyaQArepresentativeexperiencedinshotcretework.Somepanelsshouldcontainreinforcingorembeddeditemsthatwillbeincludedinthepermanentwork.Panelsshouldbesawnintostripstoallowexaminationoftheinteriorportionsofthepanels.Panelsshouldbehomogeneouswithoutlensesorpocketsofaggregateandallreinforcingandembeddeditemsshouldbecompletelyencasedindenseshotcrete.Thequalityofdry-mixshotcreteisparticularlydependentontheskillofthenozzleman,becausehisabilitytocontroltheamountofwaterbeingaddedtothemixtureandtoshoottestpanelstoqualityisessential.d.Shotcretedemonstration.Thesametestpanelevaluationtocertifythenozzlemanservestoapprovetheproductionandplacementprocess.8-3.ProductionPhaseAnongoingprogramofQAinspectionsandtestingwillberequiredtoverifycontinuedconformancewiththecontractrequirements.Consistentmaterials,mixtureproportions,andproductionmethodsarenecessaryforuniformin-placeshotcrete.a.Submittals.(1)Manufacturerscertificate.Manufacturerscertifiedtestresultsforthecementitiousmaterials,admixtures,curingmaterials,reinforcement,andfibersshouldbereviewedtoverifycontinuedconformancewiththecontractrequirements.AnychangesintheappearanceorperformanceofanyofthesematerialsshouldrequireadditionalverificationbythesupplierortestingbytheQClaboratory.(2)Testreports.Datafromtestreportsmustbereviewedtodeterminecontractcomplianceand,moreimportantly,productperformance.Consistentandvigilantreviewofdataisthebestmethodtospottrendsinmaterialqualitythatmaylaterbecomeaproblem.b.Testing.Dependingonthesizeandcriticalityoftheproject,QAtestingofmaterialsandshotcretemayberequiredtoverifycompliancewithcontractrequirements.ThesetestsareinadditiontoQCtests.TheywillalsoservetoverifytheabilityoftheQClaboratorytoproducevalidtestdata.c.VisualInspection.Thequalityoftheshotcreteshouldbethoroughlyevaluatedbyvisualinspection.Surfacesshouldbeinspectedforuniformity,voidsatthe8-1EM1110-2-200531Jan93surfaces,varyingfinishconditions,dryconditions,seepageofwater,cracking,anddamagedsections.8-2EM1110-2-200531Jan93AppendixAReferencesA-1.RequiredPublications1ER1180-1-6ConstructionQualityManagement1EM385-1-1SafetyandHealthRequirementsManual1EM1110-2-2000StandardPracticeforConcrete1CW-03361Shotcrete2USArmyEngineerWaterwaysExperimentStation1949USArmyEngineerWaterwaysExperimentStation.1949.HandbookforConcreteandCement,withquarterlysupplements(allCRD-Cdesignations),USArmyEngineerWaterwaysExperimentStation,Vicksburg,MS.3AmericanConcreteInstitute1991aAmericanConcreteInstitute.1991a.ChemicalAdmixturesforConcrete,ACIReportNo.212.3R-89,ACIManualofConcretePractice,Part2,Detroit,MI.3AmericanConcreteInstitute1991bAmericanConcreteInstitute.1991b.GuideforMeasuring,Mixing,Transporting,andPlacingConcrete,ACIReport304R-89,ACIManualofConcretePractice,Part2,Detroit,MI.1ReferencepublishedbyDepartmentoftheArmyandavailablethroughUSACECommandInformationManagementOfficesources.2AllCorpsofEngineerspublicationsareavailableoninterlibraryloanfromtheResearchLibrary,USArmyEngineerWaterwaysExperimentStation,ATTN:CEWES-IM-MI-R,3909HallsFerryRoad,Vicksburg,MS39180-6199.3ReferenceavailablethroughAmericanConcreteInstitute,POBox19150,Detroit,MI48219.4ReferenceavailablethroughAmericanSocietyforTestingandMaterials,1916RaceStreet,Philadelphia,PA19103.3AmericanConcreteInstitute1991cAmericanConcreteInstitute.1991c.StandardPracticeforCuringConcrete,ACIReportNo.308R-86,ACIManualofConcretePractice,Part2,Detroit,MI.3AmericanConcreteInstitute1991dAmericanConcreteInstitute.1991d.GuidetoShotcrete,ACIReportNo.506R-90,ACIManualofConcretePractice,Part5,Detroit,MI.3AmericanConcreteInstitute1991eAmericanConcreteInstitute.1991e.State-of-the-ArtReportonFiberReinforcedShotcrete,ACIReportNo.506.1R-84,(Reapproved1989),ACIManualofConcretePractice,Part5,Detroit,MI.AmericanSocietyforTestingandMaterials4ASTMC33(CRD-C133)StandardSpecificationforConcreteAggregates4ASTMC42(CRD-C27)StandardTestMethodforObtainingandTestingDrilledCoresandSawedBeamsofConcrete4ASTMC94(CRD-C31)StandardSpecificationforReady-MixedConcrete4ASTMC136(CRD-C103)StandardMethodforSieveAnalysisofFineandCoarseAggregates4ASTMC150(CRD-C201)StandardSpecificationforPortlandCement4ASTMC231(CRD-C41)StandardTestMethodforAirContentofFreshlyMixedConcretebythePressureMethod4ASTMC494(CRD-C87)StandardSpecificationforChemicalAdmixturesforConcrete4ASTMC597(CRD-C51)StandardTestMethodforPulseVelocityThroughConcrete4ASTMC618(CRD-C255)StandardSpecificationforFlyAshandRaworCalcinedNaturalPozzolanforUseasaMineralAdmixtureinPortlandCementConcreteA-1EM1110-2-200531Jan934ASTMC685(CRD-C98)StandardSpecificationforConcreteMadebyVolumetricBatchingandContinuousMixing4ASTMC803(CRD-C59)StandardTestMethodforPenetrationResistanceofHardenedConcrete4ASTMC805(CRD-C22)StandardTestMethodforReboundNumberofHardenedConcrete4ASTMC900(CRD-C78)StandardTestMethodforPulloutStrengthofHardenedConcrete4ASTMC1018(CRD-C65)StandardTestMethodforFlexuralToughnessandFirst-CrackStrengthofFiber-ReinforcedConcrete(UsingBeamWithThird-PointLoading)4ASTMC1141(CRD-C625)StandardSpecificationforAdmixtureforShotcreteA-2.RelatedPublications3AmericanConcreteInstitute1974AmericanConcreteInstitute.1974.UseofShotcreteforUndergroundStructuralSupport,PublicationSP-45,Detroit,MI.3AmericanConcreteInstitute1980AmericanConcreteInstitute.1980.PerformanceofConcreteinMarineEnvironment,PublicationSP-65,Detroit,MI.3AmericanConcreteInstitute1981aAmericanConcreteInstitute.1981a.ShotcreteApplications,ConcreteInternational:DesignandConstruction,Vol3,No.1,pp23-109,Detroit,MI.3AmericanConcreteInstitute1981bAmericanConcreteInstitute.1981b.ApplicationandUseofShotcrete,CompilationNo.6,Detroit,MI.3AmericanConcreteInstitute1991aAmericanConcreteInstitute.1991a.SpecificationsforStructuralConcreteforBuildings,ACIReportNo.301R-89,ACIManualofConcretePractice,Part3,Detroit,MI.3AmericanConcreteInstitute1991bAmericanConcreteInstitute.1991b.StandardSpecificationforBondingPlasticConcretetoHardenedConcretewithaMulti-ComponentEpoxyAdhesive,ACIReportNo.503.2-79(Revised1986),ACIManualofConcretePractice,Part5,Detroit,MI.3AmericanConcreteInstitute1991cAmericanConcreteInstitute.1991c.SpecificationforMaterials,Proportioning,andApplicationofShotcrete,ACIReportNo.506.2-90(Revisions),Copyright1972,1982,ACIManualofConcretePractice,Part5,Detroit,MI.3AmericanConcreteInstitute1991dAmericanConcreteInstitute.1991d.GuidetoCertificationofShotcreteNozzlemen,ACIReportNo.506.3-82,ACIManualofConcretePractice,Part5,Detroit,MI.4AmericanSocietyforTestingandMaterials1978AmericanSocietyforTestingandMaterials.1978.SignificanceofTestsandPropertiesofConcreteandConcrete-MakingMaterials,ASTMSTP169B,Philadelphia,PA.4AmericanSocietyforTestingandMaterials1992AmericanSocietyforTestingandMaterials.1992.StandardSpecificationforEpoxy-Resin-BasinBondingSystemsforConcrete,DesignationC-881-90,1992AnnualBookofASTMStandards,Philadelphia,PA;alsopublishedasCRD-C595,HandbookforConcreteandCement(withquarterlysupplements),USArmyEngineerWaterwaysExperimentStation,Vicksburg,MS.2Brekke,Einstein,andMason1976Brekke,T.L.,Einstein,H.H.,andMason,R.E.1976(Jun).State-of-the-ArtReviewofShotcrete,ContractReportS-76-4,USArmyEngineerWaterwaysExperimentStation,Vicksburg,MS.3Crom1966Crom,T.R.1966.Dry-MixShotcretePractice,Shotcreting,SP-14,pp15-32,AmericanConcreteInstitute,Detroit,MI.3Crom1981Crom,T.R.1981(Jan).Dry-MixShotcreteNozzling,ConcreteInternational:DesignandConstruction,Vol3,No.1,pp80-93,AmericanConcreteInstitute,Detroit,MI.A-2EM1110-2-200531Jan933Fredricks,Saunders,andBroadfoot1966Fredricks,J.C.,Saunders,N.R.,andBroadfoot,J.T.1966.RecentDevelopmentsinPositiveDisplacementShotcreteEquipment,Shotcreting,SP-14,pp75-83,AmericanConcreteInstitute,Detroit,MI.3Gopalaratnam,Shah,Batson,Criswell,Ramakrisknan,andWecharatana1991Gopalaratnam,V.S.,Shah,S.P.,Batson,G.B.,Criswell,M.E.,Ramakrishnan,V.,andWecharatana,M.1991(Jul-Aug).FractureToughnessofFiberReinforcedConcrete,ACIMaterialsJournal,pp339-353,AmericanConcreteInstitute,Detroit,MI.3Hoffmeyer1966Hoffmeyer,T.A.1966.Wet-MixShotcretePractice,Shotcreting,SP-14,pp59-74,AmericanConcreteInstitute,Detroit,MI.Holland1987Holland,T.C.1987(Mar).WorkingwithSilicaFumeConcrete,ConcreteConstruction,Vol32,No.3,Addison,IL.5Krantz1984Krantz,GaryW.1984.SelectedPneumaticGunitesforUseinUndergroundMining:AComparativeEngineeringAnalysis,BureauofMinesInformationCircular/1984,64pp,UnitedStatesDepartmentofInterior,Washington,DC.4Luther1989Luther,MarkD.1989.Microsilica(SilicaFume)ConcreteDurabilityinSevereEnvironments,ProceedingsoftheStructuralCongress1989,AmericanSocietyofCivilEngineers,NewYork,NY,pp95-105.5Mahar,Parker,andWuellner1975Mahar,J.W.,Parker,H.W.,andWuellner,W.W.1975(Aug).ShotcretePracticeinUndergroundConstruction,ReportNo.FRA-ORD75-90,USDepartmentofTransportation,Washington,DC.5ReferenceavailablefromNationalTechnicalInformationService,Springfield,VA22151.6Referenceavailablefrom11GrosvenorCrescent,London,SWIX,7EE,England.2McDonald1991McDonald,JamesE.1991(Mar).PropertiesofSilicaFumeConcrete,TechnicalReportREMR-CS-32,USArmyEngineerWaterwaysExperimentStation,Vicksburg,MS.3Morgan1988Morgan,D.R.1988(Jan).Dry-MixSilicaFumeShotcreteinWesternCanada,ConcreteInternational:DesignandConstruction,Vol10,No.1,pp24-32,AmericanConcreteInstitute,Detroit,MI.5Morgan,McAskill,Richardson,andZellers1989Morgan,D.R.,McAskill,N.,Richardson,B.W.,andZellers,R.C.1989.AComparativeEvaluationofPlain,PolypropyleneFiber,SteelFiberandWireMeshReinforcedShotcretes,TransportationResearchRecord,No.1226,ConcreteandConcreteConstruction,TransportationResearchBoard,NationalResearchCouncil,WashingtonDC,pp78-87.PrestressedConcreteInstitute1981PrestressedConcreteInstitute.1981(Jan-Feb).RecommendedPracticeforGlassFiberReinforcedConcretePanels,JournalofPrestressedConcreteInstitute,Vol26,No.1,pp25-93.3Reading1981Reading,T.J.1981(Jan).DurabilityofShotcrete,ConcreteInternational:DesignandConstruction,Vol3,No.1,pp27-33,AmericanConcreteInstitute,Detroit,MI.3Rutenbeck1974Rutenbeck,Todd.1974.NewDevelopmentsinIn-PlaceTestingofShotcrete,UseofShotcreteforUndergroundStructuralSupport,SP-45,pp246-262,AmericanConcreteInstitute,Detroit,MI.6Ryan1973Ryan,T.F.1973.Gunite-AHandbookforEngineers,CementandConcreteAssociation,London,England.2TynesandMcCleese1974Tynes,W.O.,andMcCleese,W.F.1974(Jul).InvestigationofShotcrete,TechnicalReportC-74-5,USArmyEngineerWaterwaysExperimentStation,Vicksburg,MS.A-3EM1110-2-200531Jan93AppendixBGlossaryofTermsAcceleratorAsubstancewhich,whenaddedtoconcrete,mortar,orgrout,increasestherateofhydrationofahydrauliccement;shortensthetimeofsetting;orincreasestherateofhardeningorstrengthdevelopment,orboth.AdmixtureAmaterialotherthanwater,aggregate,hydrauliccement,orfiberreinforcementusedasaningredientofconcreteormortarandaddedtotheconcreteimmediatelybeforeorduringitsmixing.AirRingPerforatedmanifoldinthenozzleofwet-mixshotcreteequipmentthroughwhichhigh-pressureairisintroducedintothematerialflow.AspectRatioAtermusedtodescribethegeometryofanindividualfiber;itistheratioofthelengthofafibertotheequivalentdiameter;theequivalentdiameteristhatcircularareathatisequalinareatothecross-sectionalareaofthefiber.BenchGunningWhenbuildingupthicksectionsofverticalwork,shotcreteisappliedagainsttheadvancingtopsurfaceoftheshotcreteratherthandirectlyagainsttheverticalsurface,thetopsurfaceoftheshotcreteismaintainedata45-degreeslope.(Alsoknownasshelfgunning.)BlowpipeAirjetoperatedbythenozzlemanshelperinshotcretegunningtokeepreboundorotherloosematerialoutofthework.BuildUpGunningofshotcreteinsuccessivelayerstoformathickermass.BulkingIncreaseinthebulkvolumeofaquantityofsandinamoistconditionoverthevolumeofthesamequantitydryorcompletelyinundated.CuttingScreedSharp-edgedtoolusedtotrimshotcretetoafinishedoutline.DeliveryHoseHosethroughwhichshotcretepasses;alsoknownasamaterialorconveyinghose.Dry-MixShotcretePneumaticallyconveyedshotcreteinwhichmostofthemixingwaterisaddedatthenozzle.(SeealsoPneumaticFeed.)FeedWheelMaterialdistributororregulatorincertaintypesofshotcreteequipment.FinishCoatFinalthincoatofshotcreteappliedpreparatorytohandfinishing.FlashCoatAlightcoatofshotcreteusedtocoverminorblemishesonaconcretesurfaceappliedfromadistancegreaterthannormal.GroundWireSmall-gaugehigh-strengthsteelwireusedtoestablishlineandgradeasinshotcretework;alsocalledalignmentwireorscreedwire.Gun(1)Shotcretematerialdeliveryequipmentusedtoreceivematerialsanddeliverthemtothenozzle;theequipmentoftenconsistsofdoublechambersunderpressure(equipmentwithasingle-pressurechamberisusedtosomeextent).(2)Apressurecylinderusedtopneumaticallypropelfreshlymixedconcrete.GunFinishUndisturbedfinallayerofshotcreteasappliedfromthenozzle,withouthandfinishing.Gunite(formertrademark)Amethodofapplyingdry-mixshotcrete;termsometimesusedfordry-mixshotcrete.GunmanWorkmanonashotcretingcrewwhooperatesthedeliveryequipment.GunningTheactofapplyingshotcrete;ejectionofmaterialfromthenozzleandimpingementonthesurfacetobegunned.(Sometimescalledshooting.)B-1EM1110-2-200531Jan93GunningPatternConicaloutlineofthematerialdischargestreaminshotcreteoperation.HammTipAflaredshotcretenozzlehavingalargerdiameteratmidpointthaneitherinletoroutlet;alsocalledapremixingtip.NozzleAmetalorrubbertipattachedtothedischargeendofaheavy,thick-wallrubberhosefromwhichacontinuousstreamofshotcreteisejectedontotheplacement.NozzleVelocityTherateatwhichshotcreteisejectedfromthenozzle,usuallystatedinfeetpersecondormeterspersecond.NozzlemanTheoperatorwhomanipulatesthenozzleandcontrolsplacementoftheshotcrete;inthecaseofdry-mix