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28Vol.28,Supplement200012JOURNALOFTHECHINESECERAMICSOCIETYDecember,2000(,200433):m(w)/m(c)(HPC),.:m(w)/m(c),;m(w)/m(c),HPC.,,HPC.:;;;:TU528:A:0454-5648(2000)S0-0072-04SELF-DESICCATIONMECHANISMSOFHIGH-PERFORMANCECONCRETEYangQuanbing(CollegeofMaterialsScienceandEngineering,TongjiUniversi2ty,Shanghai200433)Abstract:Effectsofm(w)/m(c)ratioandsilicafumeontheautogenousshrinkageandinternalrelativehumidityofhighper2formanceconcrete(HPC)weremainlyinvestigated.Self-desic2cationmechanismsofHPCwerealsoanalysed.ResultsshowthattheautogenousshrinkageandinternalrelativehumidityofHPCincreaseanddecreaserespectivelywiththereductionofm(w)/m(c).Theeffectsareamplifiedbytheadditionofsilicafume.Theoreticalanalysesindicatethatthereductionofinternalrelativehumidityorso-calledself-desiccationofHPCmaybemainlycausedbytheincreaseinthemoleconcentrationofsolu2bleionsinHPCandthefractionsofgelwater,absorbedwaterandinterlayerwaterinthetotalamountofevaporablewater.Keywords:high-performanceconcrete;autogenousshrinkage;self-desiccation;relativehumidity:2000-07-20.:(1964),,,.,m(w)/m(c),.,,m(w)/m(c),,[13].,[4].,,.,3d,.HPC,,,[5].HPC,.11.1,Na2O0.58%,C3A3.2%.816mm08mm.(SF),17.5m2/g,SiO298.2%.,(SP),.1.,.,.1016h,,,,.,,.1.21.2.1,Receiveddate:2000-07-20.Biography:YangQuanbing(1964),male,master,associateprofe-ssor.©1995-2005TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.1Table1Mixproportionsandpropertiesofconcretem(w)/m(c)Contentofcement+SF/(kgm-3)Aggregatecontent/(kgm-3)08mm816mmSPcontent/(kgm-3)(air)/%Slump/mmCompressivestrength/MPa28d1year0.40500+048911561.61.02258794450+5048611602.01.2215981080.37500+050311903.50.922095101450+5050011854.00.82251141260.33500+0.52212234.51.3195106111450+5051912185.01.11901181320.30500+053612489.11.2200117123450+5053312439.90.92101291400.25500+0556129312.50.7190136141450+50553128813.01.2185140155,(201)(65%2%,RH),.1.2.230cm,6cm.,2cm,1cm,50ml,.,,(Protimeter),.1.2.3,.105e;3.3kPa6hr.ere=(m0-md)/m0100%r=(mr-md)/m0100%:m0,mdmr.22.1()1m(w)/m(c)1HPC().1,,m(w)/m(c),10%,HPC,m(w)/m(c)HPC.2.2m(w)/m(c)1HPC2.2,,HPCm(w)/m(c).,10%,HPC.1m(w)/m(c)1HPCFig.1Effectofm(w)/m(c)andSFonautogeneousshrinkageofHPCof1year2m(w)/m(c)1HPCFig.2Effectofm(w)/m(c)andSFontheinternalRHofHPCof1year2.3,[4,6,7]..,3728:©1995-2005TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved..,PowersBrownyard[8],maxm(w)/m(c),m(w)/m(c),max,max=[m(w)/m(c)]/0.39.,,m(w)/m(c),,.,.,.3,,HPCHPC.,HPC.,2065%100%,W:W=(1-0.65)14.8(gm-3)5010-6m-3=2.5910-4g,:14.8(gcm-3)20,100%.,0.264g,,.,.31aHPCFig.3RelationshipbetweenshrinkageofHPCof1yearandRHRaoult,,.,,,.,:(1)Ca2+,Na+,K+,OH-,SO2-41.0%NaO2(NaO20.58%);(2).M(1L):(1)A=20.01C()62(NaO2)=3.2310-4mol(2)We=e()(3)M=A(We103)=3.2310-4C(e)M4.HPC,M,M;HPC,MHPC.,,,,M,,.4HPCMFig.4RelationshipbetweenRHandmoleconcentrationofsolubleionsinHPCconcentrationKelvin,.,,,.3.3kPa6hr,,,Ma=M(e-r)/e.Ma5.,,Ma,.,HPC.5HPCFig.5RelationshipbetweenRHandadjustedmoleofsolu2bleionsinHPCconcentration,.,m(w)/m(c)472000©1995-2005TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.,,.,,,,.3m(w)/m(c),;m(w)/m(c),HPC;.,,.,,HPC,HPC.:[1]PowersTC.Adiscussionofcementhydrationinrelationtothecuringofconcrete[A].In:HighwayResearchBoard,Proceeding[C].Japan:[s.n.],1947.2735.[2]PerssonB,FagerlundG.Internationresearchseminaronself-desic-cationanditsimportanceinconcretetechnology[D].ReportTVBM-3075.Sweden:DivisionofBuildingMaterials,LundInstituteofTechnology,1997.[3]McGrathP,HootonRD.Self-desiccationofportlandcementandsilicafumemodifiedmortars[A].In:SetzerMed.ConferenceonAdvancedCementitiousMaterials[C].1990.2226.[4]PerssonB.Self-desiccationanditsimportanceinconcretetech-nology[J].MaterialsandStructures,1997,30(6):293305.[5]PerssonB.Quasi-instantaneousandLong-TermDeformationofHigh-PerformanceConcrete(Ph.D.Dissertation)[D].ReportTVBM-1016.Sweden:DivisionofBuildingMaterials,LundInstituteofTechnology,1998.[6]MjornellKN.Self-desiccationinconcrete[D].Sweden:Depart2mentofBuildingMaterials,ChalmersUniversityofTechnology,1994.[7]SellevoldEJ,JustnesH.HighstrengthconcretebinderspartB:none-vaporablewater,self-desiccationandporosityofcementpasteswithandwithoutcondensedsilicafume[A].4thInterna2tionalConferenceontheUseofFlyAsh,SilicaFume,SlagandNaturalPozzolansinConcrete,ACISP-132[C].Michigan,USA:ACI,1992.891902.[8]PowersTC,Brownyard.Studiesofphysicalpropertiesofhar-denedportlandcementpaste[J].ResearchLaboratories,PCABulletin,1948,22:473488.(71)(4)XRD,CSH(B)C2SH(C).:[1].[M].:,1999.[2]H..[M]..:,1998.[3],,,.[M].:,1993.5728:©1995-2005TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.