Influence of mix proportions on rheology of cement grouts co(7)

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

Table5

Repeatabilityoftestparameters

Mini-slump

Mean(n¼4)

Coe cientofvariation(%)Estimatederror(95%con dencelimit)Relativeerror(%)

116.6mm5.66.6mm5.7

Platecohesionmeter0.35mm21.30.08mm21.7

ViscometerYieldvalue10.0Pa7.90.80Pa8.0

Plasticviscosity0.31Pas12.30.04Pas12.5

Inducedbleed-ingin30min1.26Lmin2.0

0.026Lmin2.1

fc07days31.1MPa10.43.3MPa10.6

743

fc028days36.2MPa7.8

2.9MPa7.9

agepredicted/measuredratiosformini-slumptest,platecohesionmeter,yieldvalue,plasticviscosity,inducedbleedingtest,andcompressivestrengthsat7and28daysaresummarisedinTable6.

Theratiosbetweenpredictedandmeasuredproper-tiesofcementgroutrangedbetween0.83and1.05,thusindicatinggoodaccuracyforestablishedmodelstopredictthemini-slumptest,yieldvalue,plasticviscosity,inducedbleeding,andcompressivestrengthat7and28days.Ingeneral,theproposedmodelstopredictmini-slump,yieldvalue,plasticviscosity,inducedbleedingandcompressivestrengthappeartobesatistifactoryinpredictingthe uidity,rheology,inducedbleedingandcompressivestrength.Ontheotherhand,theaveragevalueofpredicted/measuredratioofplatecohesionmeterwasslightlyhigher(1.45).

4.3.Isoresponsesoftheproposedmodelsofthekeyvariables

4.3.1.Mini-slump

Theproposedstatisticalmodelscanthereforebeusedtoevaluatethee ectofagroupofvariablesonthepropertiesa ectingthequalityofcementgrout.Thispermittedthecalculationoftheisoresponsecurvesfromtheparametersunderstudyovertheexperimentaldo-mainandtheoptimisationoftheire ects.AsshowninTable4,themini-slumpisin uenced,inorderofsig-ni cance,bythedosageofSP,W/B,thedosageofVA,theproportionofLSPandtheinteractione ectofW/BSP.ThedosageofSPisshowntoexhibitthegreateste ectonthemini-slump.TheincreaseinSPhasap-proximately1.8and1.5timesgreaterin uenceonin-creasingmini-slumpthanthedecreaseinthedosageofVAandtheincreaseinW/B,respectively(31.3vs.)17.6and21.4).Forexample,thee ectofincreasingW/Bratioonmini-slumpvs.theproportionofLSP,whendosagesofSPandVAwere xedat0.75%and0.05%,respectively,orvs.dosageofSPof0.75%andtheproportionofLSPof28.5%,respectively,orvs.thedosageofVAof0.05%andtheproportionofLSPof28.5%,isshowninFig.4.ForanygivenW/BratioanddosagesofSPandVA xedat0.75%and0.05%,re-spectively,themini-slumpincreasedsigni cantlywhentheproportionofLSPincreased(Fig.4(a)).Sim-ilarly,themini-slumpincreasedwhenthedosageofSPincreasedwhilethedosageofVAandtheproportionofLSPwere xed(Fig.4(c)).Ontheotherhand,the

Table6

Predicted/measuredratiosformixesofestablishedmodelsTestingmethodVeri cationpoints

Mini-slump0.97

Cohesionmeter1.45

ViscometerYieldvalue0.85

Plasticviscosity1.05

0.87

0.87

0.83

Inducedbleeding

fc07days

fc028days