the effect of coal ash glass chemistry on the tailored design of waste-based geopolymeric products

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1、TheEffectofCoalAshGlassChemistryontheTailoredDesignofWaste-BasedGeopolymericProductsLouiseM.Keyte,GrantC.LukeyandJannieS.J.vanDeventerAuthortowhomcorrespondenceshouldbeaddressed:jannie@unimelb.edu.au,Phone:+61383446619;Fax:+61383447707DepartmentofChemic

2、alandBiomolecularEngineering,TheUniversityofMelbourne,Victoria3010,AUSTRALIA.ABSTRACTGeopolymerscanbeconsideredaslow-temperatureceramicmaterials.Thesematerialsareformedbythealkalisilicatedissolutionofindustrialwastessuchascoalashandblastfurnaceslag.Atam

3、bientconditions,thedissolvedaluminiumandsiliconoxidespeciespolymeriseviaacondensationreactionandre-precipitatetoformthehardenedgeopolymer.Geopolymericmaterialsderivedfromaluminosilicatewastessuchascoalashcanexhibitsuperiorchemicalandmechanicalproperties

4、toordinaryPortlandcement(OPC).Thepresentworkwillinvestigatetherelationshipbetweencoalashcompositionandmechanicalpropertiesofvariousgeopolymers.AnalyticaltechniquesincludingquantitativeX-raydiffractionofdevitrifiedcoalflyashenablesthepredictionofflyashre

5、activityinageopolymericsystem.Thiscanleadtooptimisationandtailoringofgeopolymerformulationstospecificapplications.1.IntroductionCoalashisaby-productproducedfromtheburningofpulverisedcoalinacoal-firedboiler.Mineralsincludingkaolinite,pyriteandcalcitearep

6、resentinvaryingconcentrationsincoaldeposits.Thesemineralsdonotcombustastheypassthroughthecoalburningflame;howevertheflametemperatureissufficientforthemineralstomelt.Asthemeltedmineralsexittheflame,theyareinstantlycooledandcarriedoffwiththefluegas,andthe

7、separticlesareknownascoalash.Thisashisgenerallyseparatedintocoarseandfinefractions;thefinefractionisreferredtoascoalflyash.Flyashisafine-grained,powderparticulatematerialthatiscarriedoffinthefluegasandusuallyiscollectedbymeansofelectrostaticprecipitator

8、s,baghouses,ormechanicalcollectiondevicessuchascyclones.CoalflyashisoftenincorporatedintoOrdinaryPortlandCement(OPC)asavalueaddingfiller.Inthissystem,coalflyashisnothighlyreactive,buthasbeenshowntoimprovepropertiessuchasworkabili