土木工程外文翻译5Word文件下载.docx
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of50gofcementandshakeitinaclosedglassbottlefortwominutesandthen
revolvethesamplegentlyusingdrybar.Putthesampleinaclosedbottleandleave
itfortwominutes.Putthesamplein170sieve(90microns)andmoveit,shaking
thesievehorizontallyandrotationally,thenconfirmfinishingthesievetestwhenthe
rateofpassingcementparticlesisnotmorethan0.5g/minduringthesieveprocess.
Removethefinescarefullyfromthebottomofthesieveusingasmoothbrush.Then,
collectandweightheremainingparticlesonthesieve(W1).
Repeatthesametestwithanothersample.Thentheresidualweightforthesecond
testisobtained(W2).Calculatethevaluesoftheremainingsamplesthrough
R1=(W1/50)×
100
R2=(W2/50)×
Theratio(R)iscalculatedbytakingtheaverageofR1andR2tothenearest0.1%
and,inthecaseofdeviatingresultsofthetwosamples,morethan1%.Dothetesta
thirdtimeandtaketheaverageofthethreeresults.
Youcanacceptorrefusethecementbasedonthefollowingcondition:
ForPortlandcementt•heRmustnotexceedthan10%.
•ForrapidhardeningPortlandcementtheRmustnotexceed5%.
4.2.1.2InitialandFinalSettingTimesofCement
PasteUsingVicatApparatus
Theobjectiveofthistestistodefinethetimeforinitialandfinalsettingofthepaste
ofwaterandcementwithstandardconsistencybyusingaVicatapparatusanddetermine
whetherthecementisexpiredorcanbeused.
Theinitialsettingistherequiredtimetosetandafterthatconcretecannotbepoured
orformed;
thefinalsettingtimeisthetimerequiredfortheconcretetobehardened.
Vicatapparatus(Figure4.2)consistsofacarrierwithneedleactingunderaprescribed
weight.Thepartsmoveverticallywithoutfrictionandarenotsubjecttoerosion
orcorrosion.Thepastemoldismadefromametalorhardrubberorplasticlike
acutconewithdepthof40±
2mmandtheinternaldiameteroftheupperface70±
5mmandlowerface80±
5mmandprovidesatemplateofglassorsimilarmaterials
inthesoftersurface.Itsdimensionsaregreaterthanthedimensionsofthemold.
Theneedleisusedtodeterminetheinitialsettingtimeinasteelcylinderwith
effectivelength50±
1mmanddiameter1.13±
0.5mm.Theneedlemeasuringtime
isintheformofacylinderwithlengthof30±
0.5mmand
heldbya5mmdiameterringatthefreeendtoachievedistancebetweentheendof
theneedleandtheringof0.5mm.
Theteststartsbytakingasampleweighingabout400gandplacingitonan
impermeablesurfaceandthenadding100mlofwaterandrecordingzeromeasurement
fromthetimeofaddingwatertothecementandthenmixingfor240+5seconds
ontheimpermeablesurface.
Todeterminetheinitialsettingtimeandcalibratethedeviceuntiltheneedle
reachesthebaseofthemold,thenadjustthemeasuringdevicetozeroandreturn
needletoitsoriginalplace.
Fillthemoldwithcementpastewithstandardconsistencyandtrollthesurface,
thenputthemoldforashorttimeinaplacethathasthethetemperatureandhumidity
requiredforthetest.
SpecificSurface(Wagner)-m2/kg
365days
90days
28days
7days
20
150200250300
30
40
50
CompressiveStrength,Mpa
Transferthemoldtotheapparatusundertheneedle,andthenmaketheneedle
slowlyapproachthesurfaceuntilittouchesthepaste’ssurface,stopitinplacefor
asecondortwosecondstoavoidimpactofprimaryspeed,thenallowthemoving
partstoimplementtheneedleverticallyinthepaste.
Gradingdependsonwhentheneedlestopspenetratingorafter30seconds,whichever
isearlier,andindicatesthedistancebetweenthemoldbaseandtheendofthe
needle,aswellasthetimestartfromthezerolevelmeasurement.
Repeattheprocessofimmersingtheneedleinthesamepasteindifferentlocations
withthedistancebetweentheimmersingpointandtheedgeofthemoldor
betweentwoimmersingpointsnotless10mmafterabout10minutes,andcleanthe
needleimmediatelyaftereachtest.
Recordtimeismeasuredfromzeroupto5±
1mmfromthebaseofthemoldas
theinitialsettingtimetothenearest5minutes.Ensuringtheaccuracyofmeasurement
oftimebetweentestsreducesembedmentandthefluctuationofsuccessive
tests.Theneedleisusedtoidentifythefinaltimeofsetting;
followthesamesteps
asindeterminingtimeofinitialsettingandincreasetheperiodbetweenembedment
teststo30minutes.
Recordthetimefromzeromeasurementuntilembedmentoftheneedletoadistance
of0.5mm,whichwillbethefinalsettingtime.Controltheimpactofthe
needleonthesurfaceofthesamplesothefinalsettingtimepresentstheeffectof
theneedle.Toenhancethetest’saccuracyreducethetimebetweenembedmenttests
andexaminethefluctuationofthesesuccessivetests.Recordthefinalsettingtime
tothenearest5mm.
AccordingtotheEgyptianspecificationstheinitialsettingtimemustnotbeless
than45minutesforalltypesofcementexceptthelowheatcement,forwhichthe
initialsettingtimemustnotbeless60minutes.Thefinalsettingtimemustbeshorter
than10hoursforalltypesofcement.
4.2.1.3DensityofCement
Thepurposeofthistestistodeterminethedensityofcementbyidentifyingthe
weightandunitvolumeofthematerialbyusingtheLeChatelierdensitybottle.The
determinationofthecementdensityisessentialforconcretemixdesignandtocontrol
itsquality.ThistestfollowsspecificationsoftheAmericanSocietyforTesting
andMaterials,ASTMC188-84.
TheLeChatelierdeviceisastandardroundbottle.Itsshapeanddimensionsare
showninFigure4.3.Thisbottlemusthavealltherequireddimensions,lengths,and
uniformdegradationandaccuracy.
TheglassthatisusedintheLeChatelierbottlemustbeofhighqualityandfree
fromanydefects.Itshouldnotinteractwithchemicalsandhavehighresistanceto
heatandappropriatethicknesstohaveahighresistancetocrushing.Measurements
startatthebottle’sneckandgofromzeroto1mLandfrom18to24mLwithaccuracy
to0.1mL.Eachbottlemusthaveanumbertodistinguishitfromanyother.
Writeonthebottlethestandardtemperatureandthecapacityinmillimetersoverthe
highestpointofgrading.
Processedsamplecementweighingabout64gtothenearest0.05gmustbe
tested.
Fillthebottlewithkerosenefreefromwaterandoilwhosedensityisatleast62
API.Uptopointgradationsbetweenzeroand1mL,drytheinnersurfaceofthe
bottleatthehighestlevelofkeroseneifnecessary,anduserubberonthesurfaceof
thetableusedforthetestwhenfillingthebottle.
Thebottle,whichisfilledwithkerosene,isplacedinawaterbathandthefirst
readingtokerosenelevelisrecorded.Torecordthefirstreadingcorrectlyinstallthe
bottleinthewaterbathvertically.Putacementsampleweighing64gwithaccuracy
to0.05ginsidethebottlewithsmallbatchesatthesametemperatureofkerosene,
takingintoaccountwhenputtingthecementinsidethebottletoavoidcementdropping
outoritsadhesionontheinternalsurfacesofthebottleatthehighestlevel.The
bottlecanbeplacedonthevibratingmachinewhenputtingthecementinsidethe
bottletoexpeditetheprocessandpreventadhesionofgranulatedcementwiththe
internalsurfacesofthebottle.
Afterlayingthecementinsidethebottle,putacaponthebottlemouthandthen
spindiagonallyonthesurfacesoastoexpeltheairbetweenthegranulesofcement,
andcontinuemovingthebottleuntiltheemergenceofairbubblesstopsfromthe
kerosenesurfaceinsidethebottle.
Putthebottleinthewaterbathandthentakethefinalreading,andrecordthe
readingatthelowersurfaceofkerosenesoastoavoidtheimpactofsurfacetension.
Forthefirstandfinalreadings,makesurethatthebottleisplacedinawaterbath
withconstanttemperatureforaperiodnottoexceedthedifferenceintemperature
betweenthefirstandfinalreadingsofabout0.2°
C.
Thedifferencebetweenthefirstandfinalreadingisthevolumeofthemoving
liquidbythecementsample.
Thevolumeofthemovingliquid=finalreading–firstreading
4.2.1.4DefineCementFinenessbyUsingBlaineApparatus
Thistestisusedtodeterminethesurfaceareabycomparingthetestsamplewiththe
specificreference.Thegreatersurfaceareaincreasesthespeedofconcretehardening
andobtainsearlystrength.Thistestdeterminestheacceptanceofthecement.
TherearemanyteststodefinecementfinenessandoneisaBlaineapparatusas
statedinmanycodessuchastheEgyptiancode.
Thistestdependsoncalculatingthesurfaceareabycomparingthesampletestand
thereferencesampleusingaBlaineapparatustodeterminethetimerequiredtopass
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