土木工程外文期刊

EngineeringStructures33(2011)1025–1033ContentslistsavailableatScienceDirectEngineeringStructuresjournalhomepage:(RRC)beamsGholamrezaFathifazla,∗,A.G.Razaqpurb,O.BurkanIsgorc,AbdelgadirAbbasd,BenoitFourniere,SimonFoofaAdjeleianAllenRubeliConsultingEngineers,75AlbertStreet,Suite#1005,Ottawa,Ontario,K1P5E7,CanadabCentreforEffectiveDesignofStructures,DepartmentofCivilEngineering,McMasterUniversity,Hamilton,ON,CanadacCarletonUniversity,DepartmentofCivilandEnvironmentalEngineering,Ottawa,ON,CanadadAmecAmericas,Calgary,Alberta,CanadaeLavalUniversity,DepartmentofGeologyandGeologicalEngineering,Québec,QC,CanadafPublicWorksandGovernmentServicesCanada,Gatineau,Quebec,CanadaarticleinfoArticlehistory:Received16January2010Receivedinrevisedform11November2010Accepted9December2010Availableonline13January2011Keywords:ReinforcedconcreteShearstrengthMixproportioningWastemanagementabstractTheapplicabilityofsomemajorconcretedesignstandardsandotherpertinentmethodstocalculatetheconcretecontributiontotheshearresistanceofreinforcedrecycledconcrete(RRC)beamswithoutstirrupsisinvestigated.Resultsofarelativelycomprehensiveexperimentalprogramareusedtocomparetheactualshearstrengthofthetestedbeamswiththeircorrespondingpredictedvalues.TheconcretemixesfortheRRCbeamswereproportionedbytheso-calledEquivalentMortarVolume(EMV)method.Themethodispredicatedonthefactthatrecycledconcreteaggregate(RCA)isacompositematerial,comprisingmortarandnaturalaggregate,andthevolumetriccontentandpropertiesofeachphasemustbequantitativelyaccountedforwhenproportioningconcretemixescontainingRCA.Thetestvariablesincludedinthetestprogramareshear-span/depthratio,beamsize,RCAsource,andcoarseaggregatetype.TheresultsshowthattheshearcapacityofaRRCbeamiscomparable,orsometimessuperior,tothatofacompanionbeammadeofconventionalconcrete.Theanalysesperformedinthecurrentinvestigationshow,contrarytopreviousfindings,thatexistingsheardesignmethods,suchastheACIandCSAcodesmethods,areapplicabletoRRCbeams,providedtheEMVmethodofmixdesignisused.©2010ElsevierLtd.Allrightsreserved.1.IntroductionResearchersinthepasthavereportedthatRCA-concrete,i.e.concretecontainingrecycledconcreteaggregate(RCA),hassomeinherentlyinferiormechanicalandphysicalpropertiescomparedtonaturalaggregateconcrete(NAC),i.e.concretecontainingonlynaturalaggregate[1,2].Followinganextensiveinvestigation,thewritershypothesizedthatthereasonfortheinferioritiesreportedbyothersistheapplicationofconventionalconcretemixtureproportioningmethodstoRCA-concrete.Toverifytheprecedinghypothesis,theyproposed,andexperimentallyverified,anewmixdesignmethod.Thenewmethodwasdubbedthe‘‘equivalentmortarvolume’’(EMV)method,whichcanbeappliedtoproportionallconcretemixtures,withorwithoutRCA.ThemethodanditsverificationbyextensiveexperimentaldataarepresentedbyFathifazletal.[3].Theinvestigatedpropertiesincludeslump,freshandhardeneddensity,compressivestrength,elasticmodulus,andcompressivestress–strainrelationship.In∗Correspondingauthor.Tel.:[phone]x214;fax:[phone].E-mailaddresses:[e-mail],[e-mail](G.Fathifazl).addition,thefreeze-thaw,carbonationandchloridepenetrationresistancesofRCA-concretedesignedbytheEMVmethodwereinvestigatedandreportedelsewhere[4].Finally,largesizebeamsweretestedtostudyboththeflexuralandshearbehaviorofRCA-concretemembersdesignedbytheEMVmethod.Inallcases,theRCA-concretememberswerefoundtoshowequalorsuperiorperformancewhencomparedwiththecompanionNACmemberswhentheRCA-concretewasdesignedbytheEMVmethod[5–7].Onthecontrary,whentheRCA-concretemixeswereproportionedbytheconventionalmethod,theresultingconcretewasinmanycasesoflowerquality.Sincetheapplicationofconventionalmixproportioningmeth-odstoRCA-concretemixesgenerallyresultsinlowerqualityconcrete,membersmadeofsuchconcretealsoexhibitlowerflex-uralandshearstrengthcomparedtosimilarconventionalconcretemembers[8–11].Consequently,someinvestigatorshavereportedthatstructuralmembersmadefromRCA-concretehavelowerdi-agonalcrackingandultimateshearstrengthvalues[9–11],aswellasasmoothercrackinterface,lesseffectiveaggregateinterlockmechanismandlessductileshearbehavior[9].Thishasledtotheconclusionthattheexistingempiricalequationsforcalculatingtheconcretecontributiontotheshearresistanceofconventionalrein-forcedconcretemembersdonotapplytoRCA-concretemembers,0141-0296/$–seefrontmatter©2010ElsevierLtd.Allrightsreserved.doi:10.1016/j.engstruct.2010.12.0251026G.Fathifazletal./EngineeringStructures33(2011)1025–1033especiallytobeamswithshearspan-to-depthratiosgreaterthan3[10,11].OthershaveconcludedthattheexistingsheardesignmethodsintheACICode[12]andCanadianCSAStandard[13]maynotbeapplicabletothoseRCA-concretemembersinwhichalargefractionofthenaturalaggregateisreplacedbyRCA[11].Ifthelatterstatementsweretrue,itwouldbeasetbackforthegreaterutiliza-tionofRCAinstructuralconcreteapplicationsbecausedesignerswouldnotbeabletodesignRCA-concretemembersusingexistingcodesandconsequentlytheymayavoidRCA-concret