effect of calcium formate on properties of cement pastes containing fly ash

1、EffectofCalciumFmateonPropertiesofCementPastesContainingFlyAshAiguoWang1DaoshengSun1WeiXu1MinDeng2KaiweiLiu1TingtingZhou11.AnhuiKeyLabatyofAdvancedBuildingMaterialsAnhuiJianzhuUniversityHefei230022China2.StateKeyLabatyof

2、MaterialsientedChemicalEngineeringNanjingUniversityofTechnologyNanjing210009ChinaAbstractTheeffectofcalciumfmateonwaterrequirementofnmalconsistencycompressivestrengthdryingshrinkagerateofmasslossofcementpastescontainingf

3、lyashwerestudied.Theinfluenceofcalciumfmateonpestructurecontentofnonevapablewaterofcementpastescontainingflyashwasinvestigatedthroughmercuryintrusionposimetry(MIP)combustionmethodrespectively.Theresultsshowedthatcalciumf

4、matehaswaterreducingeffectaccelerationstheearlyhydrationofcementpastescontainingflyashtherefinementofpestructureitcanalsodecreasetherateofmassloseofcementpastesunderdryingcondition.Calciumfmatecanimprovetheearlycompressi

5、vestrengthofcementpastescontainingflyashobviouslyincreasethedryingshrinkage.Howeverincreaseofflyashreplacementcanreducetheeffectofcalciumfmateondryingshrinkageofcementpastes.iginalityFlyashisacommonsupplementarycementiti

6、ousmaterialtoreplacecement.ItislowthattheactivityofmostofflyashinChinaitsutilizationincementbasedmaterialsismelimited.Itbecomesahotspottoactivatelowactivityflyashfdomesticfeignresearchers.Howeverthemechanicalactivationre

7、quiresalotofenergytheeffectiveutilizationofenergyislowthechemicalactivationofflyashmayintroduceharmfulionswhichisunfavablefthedurabilityofconcrete.Calciumfmateisusedtomotivatetheactivityofflyashwhichisanexcitingagentwith

8、outchlideionalkali.Calciumfmatehaswaterreducingeffectaccelerationstheearlyhydrationofcementpastescontainingflyashtherefinementofpestructureitcanalsodecreasetherateofmassloseofcementpastesunderdryingcondition.Calciumfmate

9、canimprovetheearlycompressivestrengthofcementpastescontainingflyashobviously.Sotheresearchonusingcalciumfmatetopromotepropertiesofcementpastescontainingflyashisfirstiginality.Calciumfmatecanincreasethedryingshrinkageceme

10、ntpastescontainingflyash.Howeverincreaseofflyashreplacementcanreducetheeffectofcalciumfmateondryingshrinkageofcementpastes.Sotheresearchoneffectofflyashonthedryingshrinkageofcementpastescontainingcalciumfmateissecondigin

11、ality.Keywds:CalciumfmateCementpasteFlyashDryingshrinkageCompressivestrength1Crespondingauth:sundaosheng@Tel861063828100Fax861063828106%1000???LLLStt（1）whereStisthedryingshrinkage(%)L0istheinitiallength(mm)Ltisthelengtho

12、fspecimensateachage(mm)Listheeffectivelength.Testingofpestructure:aftercuringfprovidingagespecimenswerecutinto3~5mmsamplesthenmaintainedindrycuringboxwithvacuumpumpingftwohours.Afterthensampleswerestoppedhydrationinethan

13、olimmediately.Thenextdaychangedtheethanoluntilsevendays.Afterthenthesamplesweredriedat60℃fully.ThenthepevolumepesizedistributionofcementpasteweretestedbyhighperfmanceAutoPeIV9500posityfromMICROMERITICSUSA.Testingofchemic

14、allycombinedwater:aftercuringfprovidingagesomesampleswerestoppedhydrationinethanol.Afterdryingundervacuumsamplesweregrindedthrough200meshsieve.1gofthesesampleswereputintopcelaincruciblewhichwasburnedtoconstantweight.Afte

15、rdryingtoconstantweightindryingboxat60℃thesampleswereburnedat950℃ftwohours.Thevalueofchemicallycombinedwaterisdefinedasfollows(LiXetal.2009):CFACFAneWWmmmW..2211????（2）ccFAFACFAWfWfW????.（3）wherem1istheweightofsamplesbur

16、nedat60℃(g)m2istheconstantweightofcooledsamplesburnedat950℃(g)eachoffFAfCisthedosageofflyashcement(%)eachofWFAWCisignitionlossofflyashcement(%).3.ResultsDiscussion3.1.Effectofcalciumfmateontherequiredwaterofstardconsiste

17、ncyofcementpastemixedwithflyashTable3showstheeffectsofcalciumfmateontherequiredwaterofstardconsistencyofcementpastemixedwithflyash.Addingcalciumfmateintocementmixedwithflyashcanreducetherequiredwaterofstardconsistencywhi

18、chmeanscalciumfmatehaswaterreduceeffect.Tab.3EffectofcalciumfmateonwaterrequirementofnmalconsistencyofcementpastescontainingflyashSamplerequiredwaterofstardconsistency（%）Samplerequiredwaterofstardconsistency（%）P29.2P1%28

19、.7FA2029.5FA201%29.0FA3029.3FA301%28.8FA4029.6FA401%28.9FA5029.8FA501%29.13.2.EffectofcalciumfmateonthecompressivestrengthofcementpastemixedwithflyashFigure1showstheeffectsofflyashoncompressivestrengthofcementpasteswithw

20、ithoutcontainingcalciumfmate.FromFigure1(a)itisknownthatateachageasthedosageofflyashisincreasedthecompressivestrengthofcementpastesmixedwithflyashisdecreasedespeciallyat3days.FromFigure1(b)itisknownthatwhenaddingthecalci

21、umfmateintothecementpastesmixedwithflyashintheproptionsof0%20%30%40%50%thecompressivestrengthat3daysis12.1%27.4%35.6%31.3%18.7%higherthanthatofthereferencesrespectivelythecompressivestrengthat7daysis10.1%10.0%11.0%6.6%11