Influence of mix proportions on rheology of cement grouts co(8)

744L.Svermovaetal./Cement&ConcreteComposites25(2003)737–749

mini-slumpreducedwhenthedosageofVAincreasedwhilethedosageofSPandtheproportionofLSPwerekeptconstant(Fig.4(b)).

4.3.2.Platecohesionmeter

AsshowninTable4,platecohesionmeterisin u-enced,intheorderofsigni cance,bythedosagesofSPandVA,theW/BandtheproportionofLSP.Thein-creaseinW/Bhasafairlysimilarin uenceontheplatecohesionmeterastheincreaseintheproportionofLSP()0.37vs.)0.32).Bycomparingthee ectofSPandVAdosagesontheplatecohesionmeter,theincreaseofdosageofSPcanthenbeinterpretedtohaveapproxi-mately1.7timesgreaterin uenceonthereductionoftheplatecohesionvaluethantheincreaseinVA,giventhattheW/BandtheproportionofLSPareheldcon-stant.Fig.5showsanexampleofisopresponsecurvesoftheplatecohesionmetervs.W/Bfor xedvaluesofSPandVAorSPandLSPorLSPandVA.For xedvaluesofSPandVAat0.75%and0.045%,respectively,theplatecohesionmeterdecreasedwhentheW/BincreasedortheproportionofLSPincreased(Fig.5(a)).Thein-creaseofthedosageofSP,foranygivenW/Band xedLSPproportionandVAdosage,ledtoareductionintheplatecohesionmeter(Fig.5(c)).

4.3.3.Yieldvalue

AsshowninTable4,thequadratice ectofW/BLSPisshowntoexhibitthegreateste ectontheyieldvaluefollowingbythedosageofSP(2.7and)1.8).Thein-

creaseofW/BandtheproportionofLSPreducedtheyieldvalue.Themodel(Eq.(3))showsthattheincreaseofthedosageofSPismoree cientinreducingyieldvaluethananincreaseintheproportionofLSP()1.8vs.)1.1).Forexample,thee ectofincreasingW/Bratioonyieldvaluevs.theproportionofLSP,whendosagesofSPandVAwere xedat0.75%and0.05%,respectively,orvs.dosageofSPof0.75%andtheproportionofLSPof28.5%,respectively,orvs.thedosageofVAof0.05%andtheproportionofLSPof28.5%,isshowninFig.6.TheyieldvalueseemedtodecreasewithincreasedW/Bup0.40,thentendedtoincreasebeyondthisthresholdvalue(Fig.6(a)).For xeddosagesofSPandVA,theyieldvalueincreasedsigni cantlyuptoabout0.40ofW/BandhigherproportionofLSP(upto29%).AtlowerproportionsofLSP,however,adecreaseofyieldvaluewasobservedwithanincreaseinW/B(Fig.6(a)).4.3.4.Plasticviscosity

Plasticviscosityisin uenced,inorderofsigni cance,bytheW/B,thedosageofVA,thedosageofSPandtheproportionofLSP.TheW/Bisshowntohavethegreateste ectontheplasticviscosity(Eq.(4)).TheincreaseofW/Bhasapproximately1.3timesgreaterin uenceonreducingtheplasticviscositythanthede-creaseinthedosageofVA()0.56vs.0.42).Themodel(Eq.(4))showsthatthee ectofchangingthedosageofSPontheplasticviscosityissimilartothatofthepro-portionofLSP()0.28vs.0.28).Bycomparingthee ectsofSPandVAontheplasticviscosity,itcanbe

observed

L.Svermovaetal./Cement&ConcreteComposites25(2003)737–749745

thatthee ectofVAishigherthanthatofSP(0.42vs.)0.28).Forexample,thee ectofincreasingW/Bratioonplasticviscosityvs.theproportionofLSP,whendosagesofSPandVAwere xedat0.75%and0.05%respectively,orvs.dosageofSPof0.75%andthepro-portionofLSPof28.5%,respectively,orvs.thedosageofVAof0.05%andtheproportionofLSPof28.5%,isshowninFig.7.TheincreaseinW/Band/orthepro-portionofLSPledtoareductioninplasticviscosity(Fig.7(a)).

4.3.5.Inducedbleeding

Thein uencesoftheproportionofLSPandthedosagesofSPandVAarehighlysigni cantonthein-ducedbleedingaccordingtotheANOVA.Thepropor-tionofLSPisshowntoexhibitthegreateste ectasaprimaryvariableontheinducedbleedingcomparedtothedosagesofSPandVA(0.14vs.)0.05or0.04).However,theANOVAshowsthatthetwo-factorin-teractionofW/BVAishighlysigni cantandhasthegreateste ectoninducedbleeding.TheinteractionsbetweenW/BSPandW/BLSParesigni cantandhaveoppositee ect()0.1vs.0.1).TheincreaseinSPdosagehasagreaterin uenceonreducingtheinducedbleedingthantheincreaseinVAdosage()0.05vs.0.04).Forexample,thee ectofincreasingW/Bratiooninducedbleedingvs.theproportionofLSP,whendosagesofSPandVAwere xedat0.75%and0.05%,respectively,orvs.dosageofSPof0.75%andtheproportionofLSPof28.5%,respectively,orvs.thedosageofVAof0.05%andtheproportionofLSPof28.5%,isshowninFig.8.

For xeddosageofVAandtheproportionofLSP,theincreaseinSPledtoanincreaseininducedbleedingforlowerW/Bupto0.38.However,forhigherW/B(be-tween0.38and0.42),theincreaseofthedosageofSPresultedinareductionintheinducedbleeding(Fig.8(c)).Thisisduetotheimproveddispersionandpack-ingofcementgrainsassociatedwithgreaterSPdosage.Theresultingincreasein uidity(Fig.4)andparticlepacking(versus occulatedcementgrainsthathavealowerpackingdensity)cansubstantiallyreducethetendencyofwatertopercolateamongcementgrainsunderagivenhead,whichre ectsthepermeabilityofthefreshgrout.Theseresultsconcurwiththe ndingsofotherresearchers[3,4].ForlowerW/B(lowerthan0.38),theincreaseinVAdosageexhibitedareductionintheinducedbleeding,howeverforhigherW/Bbeyond0.39,theinducedbleedingseemedtoincreaseasthedosageofVAincreased(Fig.8(b)).

pressivestrength

TheANOVAsgiveninTable4showthatthee ectofW/Bishighlysigni cantoncompressivestrengthat7and28daysandhasthegreateste ectonstrength.Thecompressivestrengthdecreased,asW/Bincreased.TheproportionofLSPandthedosageofSParealsohighlysigni cantoncompressivestrength.TheincreaseoftheproportionofLSPorthedosageofSPledtoareductionincompressivestrengthat28days.Thee ectoftheproportionofLSPoncompressivestrengthwasgreaterthanthatofW/BandSP

dosage.

746L.Svermovaetal./Cement&ConcreteComposites25(2003)737–749

4.4.Trade-o betweenSPandVA

Contourresponsesshowingthein uenceofSPandVAdosagesonmini-slumpandplatecohesionmeter,andmini-slumpandyieldvalueforgroutsmadewith xedW/Bof0.35and12%ofLSParepresentedinFig.9.Asexpected,foragivenSPdosage,thecontourdia-gramsofFig.9(a)indicatethattheincreaseinVAdosagereducesthemini-slumpwhiletheplatecohesionmeterincreases.Forexample,formini-slumpof90mm,amixgroutwith0.6%ofSPand0.02%ofVAcanen-surethe uidityof90mm.TheincreaseinVAdosageto0.042%resultedinareductionofmini-slumpto75mm.However,byincreasingtheSPfrom0.6%to0.97%,themini-slumpcanbere-establishedto90mm.Forthesamemix,with0.6%ofSPand0.02%ofVA,thein-creaseinVAdosageto0.042%increasedtheplateco-hesionmeterfrom0.9to1.4mm.Theplatecohesionmetercanbere-establishedto0.9mmbyincreasingSPdosageto0.84%.

ForagivenVAdosage,theresultsfromFig.9(b)indicatethattheincreaseinSPledtoanincreaseinmini-slumpandareductionintheyieldvalue.Forex-ample,agroutmadewith0.05%ofVAand0.3%ofSPhadmini-slumpof60mmandyieldvalueof11.5Pa.TheincreaseofSPto1%resultedinanincreaseofmini-slumpto90mmandareductionofyieldvalueto10.6Pa.However,byreducingtheVAfrom0.05%to0.02%forthesameSPof0.3%,themini-slumpincreasedto75mmandtheyieldvaluedecreasedto11.25Pa.

Contourresponsesshowingthein uenceofSPandVAdosagesonplasticviscosityandinducedbleedingwithmixmadewith0.35ofW/BandLSPof12%and0.42ofW/BandLSP¼45%,arepresentedinFig.10(a)and(b),respectively.ForgivenVAandSPdosages,theincreaseofW/BandtheproportionofLSPresultedinanincreaseininducedbleedingandareductioninplasticviscosity.Forexample,forgroutmadewith0.42W/Band45%ofLSP,plasticviscosityandinducedbleedingof0.145Pasand1.40Lminareobtainedwith0.66%ofSPand0.052%ofVA.TheincreaseofSPto0.97%resultedinareductionofplasticviscosityandinducedbleedingto0.12Pasand1.30Lmin,respec-tively.With0.050%and0.3%ofVAandSP,agroutmadewith0.35ofW/Band12%ofLSPhadaplasticviscosityandinducedbleedingofapproximately0.9Pa

s

L.Svermovaetal./Cement&ConcreteComposites25(2003)737–749747

and0.95Lmin,respectively.TheincreaseofW/BandLSPto0.42and45%,respectively,wouldresultinadropofplasticviscosityto0.17Pasandanincreaseininducedbleedingto1.50Lmin.4.5.Correlationoftestingmethods

The owofgroutisverysensitivetoitsshearhistory.Theabovetestswerecarriedoutwithextremecareinordertokeeptheshearhistory,theexperimentalpro-ceduresandtheirtimingasconstantaspossible.Hence,itisinterestingtoassessthevariouspossiblecorrelationsbetweenthedi erenttestscarriedout.

Fig.11showstherelationshipbetweenthreerheo-logicalvalueswhicharecharacteristicofthegroutatlowshearrates:mini-slump,platecohesionmeterandyieldvalue.Thecoe cientofcorrelationR2betweenmini-slumpandplatecohesionmeter,andthemini-slumpandyieldvalueare0.95and0.56,respectively.Therelationshipseemedtofollowpolynomialsecond-ordermodelandshowedthatwhenthemini-slumpincreasestheplatecohesionmeterandtheyieldvaluedecrease.Therelationshipbetweenmini-slumpandtheplatecohesionmeterwasverygood.Fig.12(a)and(b)illustratethecorrelationsbetweenrheologicalcharac-teristicsofgroutsatlowandhighshearrates:theplatecohesionmeterandplasticviscosity,mini-slumpandplasticviscosity.Thecoe cientsofcorrelationbetweenplatecohesionmeterandplasticviscosity,andthemini-slumpandplasticviscosityare0.80and0.75,respec-tively(R2¼0:80wasobtainedwithouttheresultofmix3).Fig.12showsthattheincreaseinplasticviscosityledtoanincreaseinplatecohesionmeterandareductioninmini-slump.

InFig.13(a)and(b),therelationshipbetweenin-ducedbleedingandmini-slump,andinducedbleed-ingandplasticviscosityarepresented.Itseemsthatthereisnocorrelationbetweenmini-slumpandinducedbleeding.However,Fig.13(b)showsagoodrelation-shipbetweeninducedbleedingandplasticviscosity(R2¼0:85,withouttakingaccountoftheresultsfrommixes3,4and15).Theinducedbleedingwas

inversely

748L.Svermovaetal./Cement&ConcreteComposites25(2003)737–749

proportionaltotheplasticviscosity.This ndingcon- rmswhathasbeenreportedbyNedhietal.[12].

5.Conclusions

Thein uenceofdi erentW/B,dosageofSP,theproportionoflimestonepowderandthedosageofvis-cosityagentcombinationsonrheologybehaviourofcementgroutwereinvestigated.Basedontheresultspresentedinthispaper,thefollowingconclusionscanbedrawn:

(1)TheW/Bratioisshowntoexhibitagreate ect

onmini-slump,plasticviscosityandcompressivestrength.TheincreaseinW/Bratiohasanin uenceonincreasingmini-slumpandinducedbleeding,anddecreasingplasticviscosity,platecohesionmeterandcompressivestrength.

(2)Themini-slump,platecohesionmeter,andyield

valueofgroutsaredominatedprimarilybythedos-ageofSP.TheincreaseintheSPdosageledtoanincreaseinmini-slumpandareductioninplatecohesionmeter,yieldvalue,andplasticviscosity.However,theinducedbleedingseemedtoincreasewhentheSPdosageincreasedforlowW/B,andreducedwithhigherW/B.

(3)Theviscosityagentsigni cantlya ectedthemea-suredpropertiesofthisstudy,exceptcompressivestrength.TheincreaseinVAdosageisshowntoex-hibitareductioninmini-slumpandanincreaseinplatecohesionmeterandplasticviscosity.ForlowW/B,theincreaseinVAdosagereducedtheinducedbleeding,andincreaseditwhenW/Bishigher.

(4)ForagivenW/B,anddosagesofSPandVA,the

mini-slumpandinducedbleedingincreasedwhentheproportionofLSPincreased,whiletheplateco-hesionmeter,yieldvalue,plasticviscosityandcom-pressivestrengthreduced.TheLSPreplacementofcementhadagreatere ectoncompressivestrengththanthechangeofW/Bratio.

(5)Theproposedmethodcanbeusedwithothersetsof

materialssuchas yashorgroundgranulatedblast

slagasreplacementofcement,topredicttherheo-logicalpropertiesandcompressivestrengthofgroutbutthedi erencesbetweenthepredictedandmea-suredvalueswillthenindicatethee ectofthenewmaterialsontheaccuracyoftheproposedmodels.References

[1]KhayatKH,BallivyG.High-performancecementgroutforunderwatercrackinjection.In:MalhotraVM,editor.Proceed-ingsofThirdCANMET/ACIInternationalConferenceonPerformanceofConcreteinMarineEnvironment.1996.p.138–162.

[2]HoulsbyAC.Constructionanddesignofcementgrouting.In:Aguidetogroutinginrockfoundations.NewYork:JohnWileyandSons;1990.p.442.

[3]KhayatKH,YahiaA,Du yP.High-performancecementgroutforpost-tensioningapplications.ACIMaterJ1999;96(4):471–7.[4]KhayatKH,YahiaA.E ectofwelangum-high-rangewaterreducercombinationsonrheologyofcementgrout.ACIMaterJ1997;94(5):365–72.

[5]GhioVA,MonteiroPJM,DemsetzLA.Therheologyoffreshcementpastecontainingpolysaccharidegums.CemConcrRes1994;24(2):243–9.

[6]BuryJR,boratoryevaluationofauniqueanti-washoutadmixturesingrouts.In:MalhotraVM,editor.Pro-ceedingsofFifthCANMET/ACIInternationalConferenceonSuperplasticizersandotherChemicalAdmixturesinConcrete,ACISP-173,Rome,1997.p.445–473.

[7]SonebiM.Factorialdesignmodellingofmixproportionparam-etersofunderwatercompositecementgrouts.CemConcrRes2001;31(11):1553–60.

[8]SonebiM.Experimentaldesigntooptimizehigh-volumeof yashgroutinthepresenceofwelangumandsuperplasticizer.MaterStruct2002;35(250):373–80.

[9]YahiaA,KhayatKH.Experimentdesigntoevaluateinteractionofhigh-rangewater-reducerandantiwashoutadmixtureinhigh-performancecementgrout.CemConcrRes2001;31(5):749–57.[10]KhayatKH,YahiaA.Simple eldteststocharacterize uidity

andwashoutresistanceofstructuralcementgrout.CemConcrAggregates1998;20(1):145–56.[11]NehdiM,MindessS,A€ tcinP-C.Optimizationofhighstrength

limestone llercementmortars.CemConcrRes1996;26(6):883–93.

[12]NehdiM,MindessS,A€ tcinP-C.Statisticalmodellingofthe

micro llere ectontherheologyofcompositecementpastes.AdvCemRes1997;9(33):37–46.

[13]MontgomeryDC.Designandanalysisofexperiments.4thed.

USA:JohnWiley&Sons;

1996.p.704.