constructionandBuildingMaterials

Engineeringpropertiesofcontrolledlow-strengthmaterialscontainingwasteoystershellsWen-TenKuo,Her-YungWang⇑,Chun-YaShu,De-SinSuDepartmentofCivilEngineeringandDisasterMitigationTechnology,NationalKaohsiungUniversityofAppliedSciences,Kaohsiung807,Taiwan,ROChighlightsWeprovidethefeasibilityofmixingWOSwithrecycledmaterials.TheworkabilityoftheWOSCLSMwasmettherequirementsofASTMD6103.Theearly-stagecompressivestrengthofWOSCLSMisachievesASTMstandardrequirement.TheoptimalWOSreplacementof5%issuggestedforconcerningofconstruction.TheWOSisafeasiblematerialforCLSM.articleinfoArticlehistory:Received8February2013Receivedinrevisedform4April2013Accepted9April2013Availableonline23May2013Keywords:Controlledlow-strengthmaterials(CLSM)Wasteoystershells(WOS)EngineeringpropertiesDurabilityFineaggregateabstractToevaluatethepracticalapplicationofwasteoystershells(WOS)ascontrolledlow-strengthmaterials(CLSM),usingareferencesampleandfourfineaggregatereplacement5%,10%,15%and20%WOSsand,andthecementwasreplacedby20%flyashofthematerialsweretested.Thehardenedpropertiesandthedurabilityaretestedandothervariousengineeringpropertiesareinvestigated.Theexperimentalresultsdemonstratethattherewasnosignificantreductioninthecompressivestrengthupto20%ofdos-agesofWOSsandinsteadofsand,andaproperamountofflyashmaterialandWOSsandforthereplace-mentofthefineaggregateincementmortarfillsmaterialpores,reducestheabsorptionrate.WOSsandcanberesourcesofpurecalcareousmaterialsandeffectiveinreplacementofsand,indicatingappropriateapplicationofoystershells,itisfeasibletouseinCLSM.2013ElsevierLtd.1.IntroductionOverthepastdecade,moreandmorecountrieshavebeguntousecontrolledlow-strengthmaterials(CLSM).CLSMarenotstruc-turalmaterials,sotheycannotbecalledconcrete.Theyarecemen-titiousmaterials,mainlyusedascompactedfillmaterials.CLSMarealsoknownascontrolledlow-densityfills,flowablemortars,flowablefillsandleanmixbackfills[1].ACLSMisahighlyflowablematerial,usuallycomposedofwater,cement,fineaggregate,orflyashorotherbyproductmaterials.Thesimplestformiscreatedbymixingsandwithcementandwatertomakeslurryandtoaddwateraccordinglytoadjustitsflowability.TheAmericanConcreteInstituteACI229R-99[2]definesaCLSMasaself-compacting,flowable,durableandstrongcementitiousmaterialmainlyusedtoreplaceconventionalbackfillingsoilandstructuralfillings;thecompressivestrengthofthematerialis8.3MPaorlower.Com-paredwithaconventionalbackfill,theadvantagesofaCLSMarenovibration,lessfieldmanpower,easydistributionincomplexsites,nosettlement,quickness,duration,flexibility,andtheabilitytobecombinedwithnon-conventionalfieldmaterials[3].Todate,CLSMhavebeenextensivelyusedinchannelbackfillandroadre-pairengineeringinTaiwanandabroad.TheapplicationofaggregatesofCLSMfacescertainlimitations.Becausegovernmentsarepromotingpublicpoliciesofsustainabledevelopmentandgreenbuilding,therehavebeennumerousstud-iesonrecycledaggregatesinrecentyears.TheACI229alsosug-geststhatanyrecycledgranularmaterialcanbeusedasasubstituteaggregateforCLSMaslongasitistestedbeforeitisused.Non-conventionalmaterialssuchasboilerslag,recoveredglass,cementkilndust,incineratorbottomash,chipballast,crushedscrap-tirerubberparticles,fluidizedbedcombustionash,reclaimedconcreteaggregateandothersimilarindustrialbyproductshavebeenusedinCLSMassubstitutefineaggregates0950-06182013ElsevierLtd.⇑Correspondingauthor.Tel.:[phone]x5237;fax:[phone].E-mailaddress:[e-mail](H.-Y.Wang).ConstructionandBuildingMaterials46(2013)128–133ContentslistsavailableatSciVerseScienceDirectConstructionandBuildingMaterialsjournalhomepage:[4–9].Changreplacednaturalaggre-gatebyrecoveredasphaltconcretetoprepareaCLSM[10].Sheenusedoxidizingslagtoreplacefineaggregateandreplacedcemen-titiousmaterialbyreducingslagtoinvestigatetheeffectonthestrengthofCLSM[11].Razaketal.preliminarilystudiedtheperfor-manceofCLSMwithincineratorbottomashmixedcement[12].Sashaetal.usedreclaimedconcreteascoarseandfineaggregatesandflyashandslagtomakeCLSMwithoutwater[13].YaoandSunuseddunsandflyashtomakeanewtypeofsilicon–aluminum-basedbackfillmaterialanduseddifferenttemperaturestoexcitethepozzolanicreactiontostudythebackfillmaterialsystemati-cally[14].ThesestudiesindicatethatrecycledaggregatescanbeappliedtoCLSMaftermix-designexperiments.Asanislandcountry,aquacultureisoneofthekeyindustriesinTaiwan.Thesouthwesterncoastalareamainlycultivatesoysters.AccordingtothestatisticaldataoftheFisheriesAgency,theoysteryieldwasabout300,000tonsoverthelastfiveyears[15],andthequantityofWOSwasveryconsiderable.WOShavelittleutilityva-lue;thus,theyarerandomlystacked,causingproblemssuchasmosquitoesandenvironmentalpollution[16].IfWOScanberecy-cledproperly,thesourcesofpollutioninthelivingenvironmentcanbereduced.Insomecountries,sanddugfromtheseabedisusedinconcretewithoutanytreatment(e.g.,screening);thus,theconcretecontainshighseashellcontent[17–20].MoststudiesonWOSreutilizationaimatbiochemicaltechno