comparison study on volumetric deformation of gap-graded blended cement, interground blended ceme

1、ComparisonstudyonvolumetricdefmationofgapgradedblendedcementintergroundblendedcementPtlcementpastesTongshengZhang12YiqunGuo1XiangyangLiu1JiangxiongWei12QijunYu121.SchoolofMaterialsScienceEngineeringSouthChinaUniversityof

2、TechnologyGuangzhou510640China2.GuangdongLowCarbonTechnologiesEngineeringCenterfBuildingMaterialsSouthChinaUniversityofTechnologyGuangzhou510640ChinaAbstractInthisstudyvolumetricdefmationofgapgradedblendedcementpasteswit

3、hlargeamountofsupplementarycementitousmaterials(SCMs)wasinvestigatedcomparedwiththoseofPtlcementreferenceblendedcementpastes.Theresultsshowthatthegapgradedblendedcementpastespresentedahigherinitialpackingdensitytherefesm

4、alleramountofhydrationproductswasneededtoachievedensemicrostructureresultinginsmallerchemicalshrinkage.Notablymostofchemicalshrinkageofgapgradedblendedcementswasoccurredafterthefmationofskeletonstructurethustheautogenous

5、shrinkageofgapgradedblendedcementswasreducedsignificantlyduetorestraintoftheskeletonstructure.FurtherthemicrostructureofgapgradedblendedcementpasteswasdensehomogeneousduetograinsizerefinementsignificanthydrationofGBFSshr

6、inkagestresswassmallunifmlydistributed.AsaresultgapgradedblendedcementpastespresentedsmallervolumetricdefmationsuperiresistancetocrackingthanPtlcementintergroundblendedcementpastes.iginalityGapgradedblendedcementswerepre

7、paredbyarrangingSCMswithhighactivitycementclinkerSCMswithlowactivitythenthevolumetricdefmationofgapgradedblendedcementpasteswascomparedwiththoseofintergroundblendedcementPtlcementpastes.Themechanismofvolumestabilityofgap

8、gradedblendedcementpastescanbeattribuatedtotwomainaspects:1)Smallamountofhydrationproductswasneededtodensifythemicrostructureofgapgradedblendedcementpastesleadingtoasmallerchemicalshrinkage.2)Mostofcementitiousmaterialsh

9、ydratedafterthefmationofskeletonstructureleadingtoreducedautogenousshrinkageduetorestrainofhardenedpaste.Asaresultgapgradedblendedcementpasteshadsmallervolumetricdefmationsuperiresistancetocracking.Keywds:Gapgradedblende

10、dcementVolumetricdefmationChemicalshrinkageCrackingCrespondingauth:mstszhang@scut.Tel8602087114237Tab.1ChemicalcompositionsofPtlcementclinkerGBFSlowcalciumflyashChemicalcomposition(%)MaterialDensity(gcm3)SiO2Al2O3Fe2O3Ca

11、OMgOK2ONa2OSO3LOIPtlcementclinker3.1421.64.352.9563.811.760.510.161.061.19GBFS2.9035.2212.150.2537.0811.250.490.251.190.36Lowcalciumflyash2.5645.4324.366.707.531.511.230.361.037.88Note:LOIlossonignition.Figure1Particlesi

12、zedistributionsofcementitiousmaterialfractionsusedintheexperiment.Figure2ParticlesizedistributionsofPtlcementintergroundblendedcementBCFBBCFFcements.2.2.PreparationofgapgradedblendedcementsGapgradedblendedcements(BCFBBCF

13、F)werepreparedbymixingcementitiousmaterialfractionshomogenouslyaccdingtothemixproptionslistedinTable2whileintergroundblendedcementPtlcementwerepreparedbycogrindingthemixture.TheBlainespecificsurfaceareasofthesetwocements

14、werecontrolledtobeintherangeof350360m2kgwhichisseentobeequaltothoseofthegapgradedblendedcementsapproximately.Fig.2showedthatgapgradedblendedcementspresentedwiderPSDsthancementspreparedbycogrinding(intergroundblendedcemen

15、tPtlcement)whichwillleadstoahigherinitialpackingdensityofcementpaste.AlthoughgapgradedblendedcementshadsamemixproptionwithintergroundblendedcementhoweveritshouldbenotedthatGBFScementclinkerflyashwereplacedinthefinedlesiz

16、ecoarsefractionsofgapgradedblendedcementsrespectively.Tab.2MixtureproptionsofgapgradedblendedcementsPtlcementintergroundblendedcementCementitiousmaterial4μm48μm824μm2445μm4580μmContent25%11%25%19%20%BBCFFGBFSGBFSCementcl

17、inkerFlyashFlyashCementitiousmaterial8μm832μm3280μmContent36%25%39%BCFGBFSCementclinkerFlyashPtlcement100%CementclinkerIntergroundblendedcement36%GBFS25%Cementclinker39%FlyashNote:5%ofgypsumdihydratebymassofcementitiousm