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INTRODUCTIONSustainabilityofourbuiltenvironmenthasbecomeoneofthemostpromimentconsiderationsinbuildingdesignandconstruction.Thedenitionsforsustainabilityitselftakedifferentformsandhowsustainabilitymayberatediscurrentlyadevelopingscience123.TherearemanyratingsystemsthathavebeendevelopedtomeasureenvironmentalimpactanddrivesustainabledevelopmentoneexamplebeingGreenStarratingtoolspublishedbytheGreenBuildingCouncilofAustraliaGBCA4.ThisTechnicalNotehasbeenproducedbytheAshDevelopmentAssociationofAustraliatoprovideguidancetoarchitectsdesignersengineerscontractorsandinfrastructureownersinunderstandinghowbesttouseyashtoachieveenhancedsustainabilityinconstruction.Theenvironmentalimpactofusingconcretethemostcommonlyusedconstructionmaterialworldwideisbeingdebatedalongwithitsconstituentmaterialsinresearchandindustryspheres.Flyashbeingaby-productofcoalredelectricitygenerationprominentacrossAustraliahasplayedakeyroleinthisdebateoverthepast30yearsandcanpotentiallyprovidefuturesolutionstoproblemsfacedinbuildingandinfrastructureprojectswhenappliedandusedproperly.TheuseofyashasasupplementarycementitiousmaterialSCMinconcreteiswellrecognisedforitseconomicandperformanceadvantagesincludingimprovedworkabilitymixefciencyanddurability567.FlyashisalsowidelyrecognisedusedandspeciedinstandardscoveringSCMs8andGeneralPurposeandBlendedCements9.Morerecentlythefocusfortheuseofyashinconcretehasshiftedtoquantifyingbenetsofferedinenhancingconcretesustainability10.ThisTechnicalNotedetailsthebenetsyashcanprovideinproducingsustainableconcreteandhowcementreplacementwithbyproductssuchasyashcandirectlycontributetosustainabledevelopmentwhilstmaintainingothercriteriaincluding-EngineeringdesignaspectsConstructionalaspectsandEconomicadvantages.WHATISSUSTAINABLEDEVELOPMENTSustainabledevelopmentcanbegenerallydenedasdevelopmentthatmeetstheneedsofthepresentwithoutcompromisingtheabilityoffuturegenerationstomeettheirownneeds11.Itcanbebrokendownintothreecomponentsx13environmentaleconomicandsocial1213.Sustainabilityissaidtobeachievedwhenallthreecomponentsaresatised.Concretehasarelativelylowembodiedenergywhencomparedwithotherconstructionmaterials.Itisahighqualitylowcostmaterialwhichisexiblepracticalanddurableandthususedextensivelyinconstruction.Usedinsuchabundanceworldwideitsimpactonsustainabilitywhenconsideredwholisticallycanbesignicant.Thereiscurrentlysignicantdebateregardingappropriateassessmentcriteriaformeasuringenvironmentalimpactintheuseofconcreteandcomponentmaterials141516.Keyelementsthatcouldbeconsideredtoresultinamoresustainableoutcomewhenusingconcreteare-ResourcedepletionEmissionstoairintheproductionofthematerialorcomponentmaterialsembodiedenergyWaterconsumptionandWasteavoidanceandreduction.FlyashhasbeenproventohavealowerembodiedenergycomparedwithhydrauliccementasdenedinAS397291718.Appropriatedesignandcontructionconsiderationsmustbeundertakenwhenusingyashtoexploitthelowerembodiedenergybenetsandtechnicalpropertiestoachievetherequireddesignandconstructioncriteria.TheseissuesarediscussedinsomedetailintheAshDevelopmentAssociationofAustraliaTechnicalNote87.GREENSTARANDHOWTOACHIEVECREDITSGreenStarisanationalvoluntaryenvironmentalratingsystemthatevaluatestheenvironmentaldesignandconstructionofbuildings4.Itcoversdifferentcategoriesthatassessenvironmentalimpactincludingthematerialscategorywhichisfurtherdividedintodifferentmaterialcredits.Theconcretematerialscreditawardsupto3pointsfortheuseofsustainableconcrete19.Thepurposeofthecreditisdesignedx1ctoencourageandrecognisethereductioningreenhousegasemissionsresourceuseandwasteimpactsassociatedwiththeuseofconcretex1d.TheMat-5concretecreditwasrecentlyrevisedbytheGBCAandwithrespecttocementreplacementitawards1pointwherethecementcontentisreducedby30or2pointswhereitisreducedby40forallconcreteusedinaproject.CementreplacementwithyashcanthereforedirectlytranslatetoGreenStarcreditsiftheuseofyashresultsinthiscriteriabeingmet.ToevaluatereductionlevelsReferenceCasePortlandcementcontentsfordifferentstrengthgradesarenominatedinthecredit18.FLYASHTECHNICALNOTENO.1120121