Cement

Cement note(BTech - Civil Engineering Materials)

1. CivilEngineeringMaterials,Er.JayantChaudhary
pg.1
TableofContents
UNIT-5:CEMENT.....................................................................................................................................2
5.1Introdution........................................................................................................................................2
5.2ManufactureofPortlandCement....................................................................................................5
5.3ConstituentsofCement.................................................................................................................11
5.4ClinkerComposition......................................................................................................................11
5.5Hydration,HeatofHydrationandgainofstrengthofcement:.....................................................12
5.6TestonCement.............................................................................................................................16
5.7TypesofCement...........................................................................................................................17

2. CivilEngineeringMaterials,Er.JayantChaudhary
pg.2
UNIT-5:CEMENT
5.1Introdution
Cementisapowderybindermaterialwithadhesionandcohesionproperties,madebycalcining
limeandclay,whenmixedwithwaterthatsets,hardensandadherestoothermaterialstobindthemtogether.
Egyptiansmostlyusedcementingmaterials,obtainedbyburninggypsum(calciumsulfate
dihydrate,CaSO4⋅2H2O)usedintheconstructionofthecitiesofHarappaandMohenjadaro.
Fig:Gypsum
AnanalysisofmortarfromtheGreatPyramidshowedthatitcontained81.5percentcalciumsulphate
andonly9.5percentcarbonate.
TheearlyGreeksandRomansusedcementingmaterialsobtainedbyburninglimestones.
Fig:Limestone
TheGreeksandRomanslaterbecameawareofthefactthatcertainvolcanicashandtuff,whenmixed
withlimeandsandyieldedmortarpossessingsuperiorstrengthandbetterdurabilityinfreshorsalt
water.ThisvolcanictufforashmostlysiliceousinnaturethusacquiredthenamePozzolana.
TheRomans,intheabsenceofnaturalvolcanicash,usedpoweredtilesorpotteryaspozzolana.

3. CivilEngineeringMaterials,Er.JayantChaudhary
pg.3
Fig:VolcanicAsh

4. CivilEngineeringMaterials,Er.JayantChaudhary
pg.4
Fig:VolcanicTuff
InIndia.poweredbricknamedsurkhihasbeenusedinmortar.TheIndianpracticeofthroughmixing
andlongcontinuedrammingoflimemortarwithorwithouttheadditionofSurkhiyieldedstrongand
imperviousmortar.

5. CivilEngineeringMaterials,Er.JayantChaudhary
pg.5
Fig:Surkhi
ItislearntthattheRomansaddedblood,milkandlardtotheirmortarandconcretetoachievebetter
workability.Haemoglobinisapowerfulair-entrainingagentandplasticizer,whichperhapsisyetanother
reasonforthedurabilityofRomanstructures.
ThecementingmaterialmadebyRomansusinglimeandnaturalorartificialPozzolanaretainedits
positionasthechiefbuildingmaterialforallwork,particularly,forhydraulicconstruction.
Moderncement,JosephAspdin:InventedPortlandCementinU.K.in1824.Heusedamixtureof
limestone,clayandwater.Thismixturewasheatedathightemperatures.On21stoct,1824was
grantedapatent.
Fig:PortlandStone
5.2ManufactureofPortlandCement
TherawmaterialsrequiredformanufactureofPortlandcementarecalcareousmaterials,suchaslimestoneor
chalk,andargillaceousmaterialsuchasshaleorclay.
Theprocessofmanufactureofcementconsistsofgrindingtherawmaterials,mixingthemintimatelyincertain
proportionsdependingupontheirpurityandcompositionandburningtheminakilnatatemperatureofabout
1300to1500°C,atwhichtemperature,thematerialsintersandpartiallyfusestoformnodularshapedclinker.
Theclinkeriscooledandgroundtofinepowderwithadditionofabout3to5%ofgypsuminordertoincrease
settingtime.FlyAsh(1%)isalsousedasanadmixturethesedaystoimproveworkabilitybutdoesnotaffectthe
strength.TheproductformedbyusingthisprocedureisPortlandcement.

6. CivilEngineeringMaterials,Er.JayantChaudhary
pg.6
TypesofMaterials
Calcareous(CaO) Argillaceous(Al2O3) Siliceous(SiO2)
Limestone Shale Sandstone
Chalk Clay Silica
MarineShells CementRock
CementRock Chalk
BlastFurnaceSlag
Marl
Basicconstituentsofallthematerialsonandinsideearth'ssurfaceare:-
Lime,Silica,Alumina,IronOxide,Magnesia,etc.
RawMaterial
Extraction&
Storage
Correctionof
Proportions
Pulverization
(PowderyForm)
inBallMill
PulverizeClinker
andaddGypsum
Formationof
ClinkerandIts
Cooling
CalcinationinKiln
(Heating)-enables
fusion
Storageand
Packing
Fig:Clinker

7. CivilEngineeringMaterials,Er.JayantChaudhary
pg.7
WetandDryProcess
Therearetwoprocessesknownas“wet”and“dry”processesdependinguponwhetherthemixingand
grindingofrawmaterialsisinwetordryconditions.Withalittlechangeintheaboveprocesswehavethe
semi-dryprocessalsowheretherawmaterialsaregrounddryandthenmixedwithabout10-14percent
ofwaterandfurtherburnttoclinkeringtemperature.
WetProcess
Limestonecollectedfromquarriesshouldfirstcrushtosmallerfragments.
Crushedmaterialsarefedtoballortubemill-mixedwithclaywithadditionoflittlewater–
slurry(35-50%water)-Correctedslurry(testedforchemicalcomposition)isthenfedtorotary
kiln.
Rotarykilnhasthediameterofabout3-8mandlengthof30-200mlinedwithrefractory
material.
Slurrymovesonhotchainsandlossesmoisturecalledflakesandthensubjectingtomove
upanddownandFusingprocesstakesplaceattemperatureofabout1400-1500°C.
Duringthisprocessabout20-30%materialgetsfusedandlime,silicaandaluminaget
recombined.
Thefusedmassturnstonodularformofsizeabout3-20mmknownasclinkerandcollected
inSILOSandweighs1100-1300gm/lt.
ClinkeriscooledandGypsum-2-3%(CaSO4.2H2O)isaddedtopreventfromflash-
settingofcement-increaseinitialsettingtime.
Theballmillandtubemillcontainseveralcompartmentsandproducedefinedfinenessof
cement.
Thematerialisthenfedtopackingunit.

8. CivilEngineeringMaterials,Er.JayantChaudhary
pg.8
Coal/fuelrequiredisabout350Kgfor1-tonproduction.
DryProcess
a.Treatmentofrawmaterials:Crushing,drying,grinding,proportioningandblending(mixing)of
Limestoneandclay.
Breakingofrawmaterialto6-14mmusingcrushers.
Rotarydryingkilnisusedtodrythecrushedmaterials.
GrindingisdoneintwostagesasballmillandtubemillsandstoredinSILOS.
Proportioningandblendingtherawmaterialsindifferentstageswithaddinglowquantity
ofwater-12%.
b.BurningorCalcinations:Well-proportionedpowderedmixtureischargedintorotarykiln.
Thegreenishblackcoloredglasslikelusturematerialcalledclinkerispreparedinthisstage.
Duringthisprocessupto400°Cdehydration(lossofwater)takesplaceinitially.Then
dissociation(theactionofdisconnecting)ofCa&Mgcarbonatesproceedsupto800°Cto
900°CandthenC2S,C3S,C3A,C4AFcompoundformedupto1300°Cto1400°C-Clinker.
c.GrindingoftheClinker:Calcinedhotclinkerisfirstfedintocoolingchamberandthen
Gypsumisaddedandmixtureispulverized.Thengrindingisdoneintwostageascoarsergrinding
andfinergrinding.

9. CivilEngineeringMaterials,Er.JayantChaudhary
pg.9
d.Packingandstorageofcement:Placedfirstintoconcretestoragetanks-SILOSandpacked
intohighdensitypolyethylenebags,juteandpackingclothsof50Kgcapacity.Coal/Fuel
consumptionisabout120Kgfor1-tonproduction.
Itisimportanttonotethatthestrengthpropertiesofcementareconsiderably
influencedbythecoolingrateofclinker.

10. CivilEngineeringMaterials,Er.JayantChaudhary
pg.10
DifferencebetweenDryandWetProcessofmanufacturingofcement
S.N.DryProcess WetProcess
1
Inthisprocesscalcareousmaterialsuchas
limestone(calcium carbonate)and
argillaceousmaterialsuchasclayare
groundseparatelytofinepowderinthe
absenceofwaterandthenaremixed
togetherinthedesiredproportions.A
quantityofwaterabout12percentbyweight
isthenaddedtomaketheblendedmealinto
pellets.
Inthisprocess,rawmaterialsarepulverized
byusingaballmill.Whenthemillrotates,
steelballspulverizetherawmaterialswhich
formslurry(liquidmixture).Theslurryis
thenpassedintostoragetanks,where
correctproportioningisdone.Corrected
slurryisthenfedintorotarykilnforburning.
Propercompositionofrawmaterialscanbe
ensuredbyusingwetprocessthandry
process
2
Inthisprocess,mixingandgrindingofraw
materialsisdoneindrystateonly.
Inthisprocess,mixingandgrindingofraw
materialsisdonebyadding30-50%water
init.
3
Thisprocessisusuallyusedwhenraw
materialsareverystrongandhard.
Thisprocessisusuallyusedwhenraw
materialsaresoftbecausecompletemixing
isnotpossibleunlesswaterisadded.
4
Theheatingisdoneat1300°Cto1400°Cin
kiln.
Theheatingisdoneat1400°Cto1500°Cin
kiln.
5
Lessfuelrequirementsinkiln.Thetotal
consumptionofcoalinthismethodisonly
about100kgwhencomparedtothe
requirementofabout350kgforproducinga
tonofcementinthewetprocess.
Highfuelrequirementsinkiln-fuelneededto
evapourate30%plusslurrywaterhence,it
iscostlierthandryprocess
6
Partlyroundedburntproducti.e.clinkers
forms.
Elongatedburntproductformsafterburnt.
7
Nocontrolonmanufacturinghencemore
wastagemaytakesplace.
Fullycontrolledmanufacturinggive
minimumwastageofmaterials.
8
ifweconsiderfuelconsumptionandtimeof
processthendryprocessisbetter.
Ifweconsiderthequalityandratethenwet
processisbetter
9 Almost,74%ofcementisproduced. Almost,26%ofcementisproduced.

11. CivilEngineeringMaterials,Er.JayantChaudhary
pg.11
5.3ConstituentsofCement
Constituents/IngredientsofCementandTheirRole
S.N.Constituents Functions AverageComposition
1 Lime(CaO)
ControlStrength&Soundness.IfLime
decreases,Strength&settingtime
decreases.
60-65(63%)
2 Silica(SiO2)
Givesstrength.IfIncrease,itincreases
slowsetting.
17-25(20%)
3 Alumina(Al2O3)
Responsibleforquicksetting,ifinexcess
itlowersthestrength
3-8(6%)
4 IronOxide(Fe2O3)
Givescolour&helpsinfusionofdifferent
ingredients.Rendersthehighlysiliceous
materialseasiertoburn.Ifinexcess,a
hardclinker,difficulttoground.
0.5-6(3%)
5 Magnesia(MgO)
Impartscolour&hardness.Ifinexcess,
causescracksinmortar&concreteand
leadstounsoundness
0.5-4(2%)
6
Soda+Potash
(Na2O/K2O+H2O),
Alkalies
Residues,causesefflorescenceand
cracking.
0.5-1(1%)
7
Sulphur Trioxide
(SO3)
Makescementunsound 1-2(1.5%)
5.4ClinkerComposition
WhenRawMaterialsfusesinKiln,theresultantcompoundsproducedareBoquecompound
Forhighstrengthdevelopmentpropercooling:-1200°C(15min)-500°C(10min)-Ambient
Temperature
S.N.Principalmineralcompounds Formula NameSymbol
1 Tricalciumsilicate 3CaO.SiO2 Alite C3S
2 Dicalciumsilicate 2CaO.SiO2 BeliteC2S
3 Tricalciumaluminate 3CaO.Al2O3 CeliteC3A
4 Tetracalciumaluminoferrite 3CaO.Al2O3.Fe2O3FeliteC4AF
Besidesthesemajorcompounds,alkaies(Soda&Potash),Calciumsulphate(gypsum)arealso
present
1.Tricalciumsilicate,C3S-25-50%(Average=40%)
Itprovidesbestcementingproperty,Verygoodbindingqualityanditsformedwhencementis
wellburnt.
Itprovidesearlystrengthandisresponsiblefor7daysstrength.
Thestrengthofcementinfirst28daysisduetoC3S.
Itenablesclinkereasytogrind&increaseresistancetofreezingandthawing.

12. CivilEngineeringMaterials,Er.JayantChaudhary
pg.12
Generateshighheatofhydrationandincreasesolubilityofcementinwater.
Highheatofhydration=500J/gm
2.Dicalciumsilicate,C2S-25-40%(average=32%)
Ithydratesandhardensslowlyandtakeslongtimetoaddtostrengththatislaterstrength.
(ultimatestrength)
Itenablesclinkerhardtogrind&decreaseresistancetofreezingandthawing.
Generateslowheatofhydrationanddecreasessolubilityofcementinwater.
Itimpartschemicalresistance.
Highheatofhydration=260J/gm
3.Tricalciumaluminate,C3A-5-11%(average=10.5%)
Itreactsimmediatelywithwaterandisresponsibleforflashset(initialset).
Itisthefirstcompoundtoreactwithwater.
Therapidityofactionisregulatedbytheadditionof2-3%ofgypsumatthetimeofgrinding
cement.
Itdecreasessettingtime,henceincreasedshrinkageandcracking
itweakensresistancetosulphateattack.
Volumechangeincreaseandhencecracking.
Highheatofhydrationincreaseandlowersultimatestrength.
Highheatofhydration=865J/gm
4.Tetracalciumaluminoferrite,C4AF-8-14%(average=9%)
Responsibleforflashsetbutgenerateslessheat
Poorestcementingvalue.
Ifincreases,itdecreasesstrength
ThehydratesofC4AFshowacomparativelyhigherresistancetotheattackofsulphatesthan
thehydratesofcalciumaluminate,C3A.
Highheatofhydration=420J/gm
HighPercentageofC3SandlowC2Sresult:
Rapidhardening
Highearlystrengthandhighheatgeneration
Lessresistancetochemicalattack
LowPercentageofC3SandhighC2S
result:
Slowhardening
Muchmoreultimatestrengthwithlessheatgeneration
Greaterresistancetochemicalattack
5.5Hydration,HeatofHydrationandgainofstrengthofcement:
HydrationofCement
Anhydrouscementdoesnotbindfineandcoarseaggregate.Itacquiresadhesiveproperty
onlywhenmixedwithwater.Thechemicalreactionsthattakeplacebetweencementand
waterisreferredashydrationofcement.
Thequality,quantity,continuity,stabilityandtherateofformationofthehydrationproducts
areimportant.

13. CivilEngineeringMaterials,Er.JayantChaudhary
pg.13
Thehydrationofcementcanbevisualisedintwoways.Thefirstis“throughsolution”
mechanism.Inthisthecementcompoundsdissolvetoproduceasupersaturatedsolution
fromwhichdifferenthydratedproductsgetprecipitated.Thesecondpossibilityisthatwater
attackscementcompoundsinthesolidstateconvertingthecompoundsintohydrated
productsstartingfromthesurfaceandproceedingtotheinteriorofthecompoundswithtime.It
isprobablethatboth“throughsolution”and“solidstate”typesofmechanismmayoccurduring
thecourseofreactionsbetweencementandwater.
Whenwaterisaddedtocement,eachofthecompoundsundergoeshydrationand
contributestothefinalconcreteproduct.Onlythecalciumsilicatescontributetostrength.
Tricalciumsilicateisresponsibleformostoftheearlystrength(first7days).Dicalciumsilicate,
whichreactsmoreslowly,contributesonlytotheultimatestrengthatlatertimes.
TheproductC–S–H(C3S2H3)gelrepresentsthecalciumsilicatehydratealsoknownas
tobermoritegelwhichisthegelstructure.TheC–S–Hphasemakesup50–60%ofthe
volumeofsolidsinacompletelyhyderatedPortlandcementpasteandis,therefore,the
mostimportantindeterminingthepropertiesofthepaste.
Thegelmustbesaturatedwithwaterifhydrationistocontinue.Thecalciumhydroxide
crystalsformedintheprocessdissolveinwaterprovidinghydroxyl(OH–)ions,whichare
importantfortheprotectionofreinforcementinconcrete.Ashydrationproceeds,thetwo
crystaltypesbecomemoreheavilyinterlockedincreasingthestrength,thoughthemain
cementingactionisprovidedbythegelwhichoccupiestwo-thirdsofthetotalmassof
hydrate.
TheCa(OH)2liberatedduringthesilicatephasecrystallizesintheavailablefreespace.
Thecalciumhydroxidecrystalsalsoknownasportlanditeconsistsof20-25%volumeof
thesolidsinthehydratedpaste.Thelackofdurabilityofconcrete,isonaccountofthe
presenceofcalciumhydroxide.Thecalciumhydroxidealsoreactswithsulphatespresentin
soilsorwatertoformcalciumsulphatewhichfurtherreactswithC3Aandcausedeterioration
ofconcrete.Thisisknownassulphateattack.ToreducethequantityofCa(OH)2in
concreteandtoovercomeitsbadeffectsbyconvertingitintocementitiousproduct
isanadvancementinconcretetechnology.Theuseofblendingmaterialssuchasfly
ash,silicafumeandsuchotherpozzolanicmaterialsarethestepstoovercomebad
effectofCa(OH)2inconcrete.TheonlyadvantageisthatCa(OH)2,beingalkalineinnature
maintainpHvaluearound13intheconcretewhichresiststhecorrosionofreinforcements.
IthasbeenfoundthathydrationofC3Sproduceslessercalciumsilicatehydrateand
moreCa(OH)2ascomparedtothehydrationofC2S.SinceCa(OH)2issolubleinwater
andleachesoutmakingtheconcreteporous,particularlyinhydraulicstructures,a
cementwithsmallpercentageofC3SandmoreC2Sisrecommendedforusein
hydraulicstructures.
ThetricalciumaluminateHydrate,C3Ah6totricalciumsilicateacceleratedthehydration
process,reducedsettingtimeandimprovedthecompressivestrength.
Itisparticularlyimportanttonotethatthesetting(thechangeofcementpastefrom
plastictostiffsolidstate)andhardening(gainofstrengthwithhydration)isa

14. CivilEngineeringMaterials,Er.JayantChaudhary
pg.14
chemicalreaction,whereinwaterplaysanimportantrole,andisnotjustamatterof
dryingout.Intact,settingandhardeningstopassoonastheconcretebecomesdry.
RateandHeatofHydration
Theprocessbywhichcement,aggregatesandwatermixandformanewsubstanceisa
chemicalprocesswhichhasitsownuniquepropertiesandproducts.Themainproductofthe
bindingofcementandwaterisheat,whichisgivenoffduringthehardeningoftheconcrete.
Thisisknownastheheatofhydration.
Whenheatofhydrationistakenintoconsiderationwhiledesigningandpouringconcrete,it
canbemanagedproperlyduringthecuringandhardeningprocess.However,ifthedesigners
donotallowfortheheat,itcancauseissueswithcrackingandpossiblyevencompromisethe
structuralintegrityoftheconcrete.Itisextremelyimportanttoknowaboutheatofhydration
anditseffectsonconcretefromthetimeitispouredandthroughoutitslifetime.
ThereactionofcompoundC3Awithwaterisveryfastandisresponsibleforflashsettingof
cement(stiffeningwithoutstrengthdevelopment)andthusitwillpreventthehydrationofC3S
andC2S.However,calciumsulphate(CaSO4)presentintheclinkerdissolvesimmediatelyin
waterandformsinsolublecalciumsulphoaluminate.ItdepositsonthesurfaceofC3Aforming
acolloidalmembraneandconsequentlyretardsthehydrationofC3A.
ThehydratesofC4AFshowacomparativelyhigherresistancetotheattackofsulphatesthan
thehydratesofcalciumaluminate,C3A.
ThehardeningofC3ScanbesaidtobecatalyzedbyC3AandC3Sbecomessolely
responsibleforgainofstrengthupto28daysbygrowthandinterlockingofC-S-Hgel.The
increaseinstrengthatlaterageisduetohydrationofC2S.
Therateofheatevolutionofthecompoundsifequalamountofeachis
consideredwillbeinthefollowingorder:C3A>C3S>C4AF>C2S
Therateofhydrationisincreasedbyanincreaseinfinenessofcement.However,totalheat
evolvedisthesame.Therateofhydrationoftheprincipalcompoundswillbeinthefollowing
order:C4AF>C3A>C3S>C2S
WaterRequirementforHydration
Aboutanaverage23percent(24percentC3S,21percentC2S)ofwaterbyweightofcementis
requiredforcompletehydrationofPortlandcement.Thiswatercombineschemicallywiththe
cementcompoundsandisknownasboundwater.Somequantityofwater,about15percent

15. CivilEngineeringMaterials,Er.JayantChaudhary
pg.15
byweightofcement,isrequiredtofillthecementgelporesandisknownasgelwater.
Therefore,atotalof38percentofwaterbyweightofcementisrequiredtocompletethe
chemicalreaction.Thegeneralbeliefthatawater/cementratiolessthan0.38shouldnotbe
usedinconcretebecausefortheprocessofhydration,thegelporesshouldsaturated-isnot
valid.Thisisbecauseasevenifexcesswaterispresent,completehydrationofcementnever
takesplaceduetodepositionofhydrationproducts.Asamatteroffactwater/cementratioless
than0.38isverycommonforhighstrengthconcretes.Ifexcesswaterispresent,itwillleadto
capillarycavities.
SulphateAttack
Sulphateattackonconcreteisachemicalbreakdownmechanismwheresulphateionsattack
componentsofthecementpaste.
Thecompoundsresponsibleforsulphateattackonconcretearewater-solublesulphate-
containingsalts,suchasalkali-earth(calcium,magnesium)andalkali(sodium,potassium)
sulphatesthatarecapableofchemicallyreactingwithcomponentsofconcrete.
Solidsulphatesdonotattacktheconcreteseverelybutwhenthechemicalsarein
solution,theyfindentryintoporousconcreteandreactwiththehydratedcement
products.Ofallthesulphates,magnesiumsulphatecausesmaximumdamageto
concrete.Acharacteristicwhitishappearanceistheindicationofsulphateattack.
Thetermsulphateattackdenoteanincreaseinthevolumeofcementpasteinconcrete
ormortarduetothechemicalactionbetweentheproductsofhydrationofcement
andsolutioncontainingsulphates.Inthehardenedconcrete,calciumaluminatehydrate
(C-A-H)canreactwithsulphatesaltfromoutside.Theproductofreactioniscalcium
sulphoaluminate,formingwithintheframeworkofhydratedcementpaste.Becauseofthe
increaseinvolumeofthesolidphasewhichcangoupto227percent,agradual
disintegrationofconcretetakesplace.
Sulphates
[Ma,Ca,etc]
Hydration
SourcesofSulphates
Mostsoilscontainsomesulphateintheformofcalcium,sodium,potassiumand
magnesium.
Theyoccurinsoilorgroundwater.Becauseofsolubilityofcalciumsulphateislow,
groundwaterscontainmoreofothersulphatesandlessofcalciumsulphate.
Ammoniumsulphateisfrequentlypresentinagriculturalsoilandwaterfromtheuseof
fertilizersorfromsewageandindustrialeffluents.Decayoforganicmattersinmarshy
land,shallowlakesoftenleadstotheformationofH2S,whichcanbetransformedinto
sulphuricacidbybacterialaction.
Waterusedinconcretecoolingtowerscanalsobeapotentialsourceofsulphate
attackonconcrete.Thereforesulphateattackisacommonoccurrenceinnaturalor
industrialsituations.

16. CivilEngineeringMaterials,Er.JayantChaudhary
pg.16
5.6TestonCement
Testingofcementcanbebroughtundertwocategories:
(a)Fieldtesting
(b)Laboratorytesting.
FieldTesting
Itissufficienttosubjectthecementtofieldtestswhenitisusedforminorworks.Thefollowingare
thefieldtests:
Openthebagandtakeagoodlookatthecement.Thereshouldnotbeanyvisiblelumps.
Thecolourofthecementshouldnormallybegreenishgrey.
Thrustyourhandintothecementbag.Itmustgiveyouacoolfeeling.Thereshouldnotbe
anylumpinside.
Takeapinchofcementandfeel-betweenthefingers.Itshouldgiveasmoothandnota
grittyfeeling.
Takeahandfulofcementandthrowitonabucketfullofwater,theparticlesshouldfloatfor
sometimebeforetheysink.
Athinpasteofcementshouldfeelstickybetweenfingers.
Thefollowingtestsareusuallyconductedinthelaboratory.
(a)Finenesstest.
(bConsistencytest
(c)Settingtimetest.
(d)Soundnesstest.
(e)Strengthtest.
(f)Heatofhydrationtest.
(g)Chemicaltest.

17. CivilEngineeringMaterials,Er.JayantChaudhary
pg.17
5.7TypesofCement
1.OrdinaryPortlandCement(OPC)
Thecommon3gradesare:-OPC33,OPC43,OPC53
3daysstrength=50%(1/2)of28daystrength.
7daysstrength=67%(2/3)of28daystrength.
Fineness=2250cm
2
/gm
Initialsettingtime>=30minandFinalSettingtime<=10hr(600min)
soundnesstestnotgreaterthan10mm(LeChateliermethod)andByautoclavetestmethod,
percent,Max0.8
OPC33:
33gradecementmeansthatthecompressivestrengthofthecementafter28daysis
33N/mm
2
whentestedasperIndianStandardsunderstandardconditions.Thisgradeof
cementisusedforgeneralconstructionworkundernormalenvironmentalcondition.Itmaynot
besuitableforconcretegradeaboveM20.
Rarelyusednowadays.AsmostofthemshiftedtoPPC.
OPC43:
43gradecementmeansthatthecompressivestrengthofthecementafter28daysis43
N/mm
2
whentested.
Thisgradeofcementisusedforplainconcreteworkandplasteringworks.Itissuitableto
makeconcretemixuptoM30.
43GradeOPCCementiscommonlyusedforplasteringworks,Non-RCCstructures,pathways
etc.alsousedtomakeprecastitems,suchastiles,blocks,pipes,etc.
Unlessaprojectrequiresveryhighstrengthcement,theuseof43GradeOPCisgenerally
recommendedingeneralcivilconstructionworksuchasresidential,commercialandindustrial
structures.ItisusedinRCCworks,preferablywherethegradeofconcreteisuptoM-30.
ThebestcementinIndiaforplasteringlow-riseresidentialbuildingsisOPC43,whereasthe
finestcementforplasteringhigh-risestructuresisOPC53.
Fininishingofalltypesofbuilding,bridges,culverts,Road,waterretainingstructures,etc.
OPC53
53gradecementmeansthatthecompressivestrengthofthecementafter28daysis53
N/mm
2
whentested.53gradecementhasafastsettingtimeascomparedto43gradecement.
Thisgradeofcementisnotusedforordinaryworks.Itismostlyusedforstructuralpurposesas
inreinforcedcementconcrete.
UsedinBeam,Column,Footin,Slab,Bridge,railway,
53GradeOPCprovideshighstrengthanddurabilitytostructuresbecauseofitsoptimum
particlesizedistributionandsuperiorcrystallizedstructure.

18. CivilEngineeringMaterials,Er.JayantChaudhary
pg.18
2.RapidHardeningCement(RHC)
Itisalsoknownashighearlystrengthcement.Developsstrengthrapidly.
HighlimecontentforthisC3Sisincreased,C2Sisdecreased+finergrinding.
Fineness=3250cm
2
/gm.Thisfactorhelpsquickerandcompletehydrationofcementparticle
duringsetting.
Theexpansionofcementislimitedto10mm.
Rapidhardeningcementdevelopsattheageofthreedays,thesamestrengthasthatis
expectedtodevelopinOPCat7days.
Initialsettingtime=30min&Finalsettingtime=10hr(600min)
1daycompressivestrength=16N/mm
2
3daycompressivestrength=27.5N/mm
2
Theextrafineness,however,maybeoftenthecauseofdevelopmentofcracks.Givesmuch
heatofhydrationsonotusedinmassconcreteconstruction
RHCisnotusedinthinRCCmember.
RHCisusedsothatstengthisgainedbeforewaterisfreezeincoldestclimate.
Uses:-Pre-fabricatedconcretework,fastremovalofformwork,roadrepairworksandcold
weatherconcretetopreventfromfrostaction.
3.ExtraRapidHardeningCement(ERHC)
Itisalsoknownascalciumchloridecement
RHC+2%CaCl2
Thenormaladditionofcalciumchlorideshouldnotexceed2percentbyweightoftherapid
hardeningcement.
Thestrengthofextrarapidhardeningcementisabout25percenthigherthanthatofrapid
hardeningcementatoneortwodaysand10–20percenthigherat7days.
Uses:-Roadrepairs,incoldcountries,forfastremovalofshutter.
Mixing+Transporting+Placingofconcreteshouldbewithin10min.
Accelerator=CalciumChloride
4.HighAluminaCement(HAC)
Bauxite+limestone+ironoxide+increasefineness+hightemperature
ItissimilartoRHCbutC3Aisabsent.
Initialsettingtime=3.5hr-4hr&Finalsettingtime=5-6hr
1daycompressivestrength=30N/mm
2
Uses:-Roadrepairs,incoldcountries,forfastremovalofshutter,refractorycement(hear
resistant),highchemicalresistance(nosulphateattack)

19. CivilEngineeringMaterials,Er.JayantChaudhary
pg.19
5.SulphateResistingCement(SRC)
ItissimilartoOPCbutC3Aisdecreased+finergrinding
Fineness=2250cm
2
/gm.
Theexpansionofcementislimitedto10mm.
Initialsettingtime≤30min&Finalsettingtime≥10hr(600min)
Usedwhenclimatetemperature<40°C
Uses:-Liningofsewers,canals,incoastalareas,inseawaters,Marineconstruction,
foundationandbasements,fabricationofpipes
ThiscementcanbeusedasanalternativetoordinaryPortlandcementorPortlandpozzolana
cementorPortlandslagcementundernormalconditions.
5.SuperSulphatedPortlandCement(SSPC)
80-85%granulatedslag+10-15%CaSO4+5%ClinkerOPC+Finergrinding
WaterresistanceofconcretesfromsupersulphatePortlandcementsishigherthanthatof
commonPortlandcementsbecauseoftheabsenceoffreecalciumoxidehydratewhereas
concretesfromPortlandcementcarryalargeamountoffreecalciumoxidehydratewhichmay
washoutandthusweakenthem
Ithaslowheatofhydrationandisresistanttochemicalattacksandinparticulartosulphates.
Fineness=4000cm
2
/gm.
Theexpansionofcementislimitedto5mm.
Initialsettingtime≤30min&Finalsettingtime≥10hr(600min)
Usedwhenclimatetemperature<40°C
Uses:-Liningofsewers,canals,incoastalareas,inseawaters,Marineconstruction,
foundationandbasements,fabricationofpipes
Thiscementshouldnotbeusedinconstructionsexposedtofrequentfreezing-and-thawingor
moistening-and-dryingconditions
6.PortlandSlagCement(PSC)
Portlandcementclinker+granulatedblastfurnaceslag+gypsum
Thechemicalrequirements,initialandfinalsettingtimes,compressivestrengthofPortland
slagcementaresameasthatofOPCcement.
Fineness=2250cm
2
/gm
Initialsettingtime>=30minandFinalSettingtime<=10hr(600min)
soundnesstestnotgreaterthan10mm(LeChateliermethod)andByautoclavetestmethod,
percent,Max0.8
Highchemicalresistance(sulphateresistance),lowheatofhydration,lowrateofstrength
developmentthanOPCcement.
Uses:-Marineworks,Massconcretework
7.LowHeatCement(LHC)
LowcontentsofC3AandC3SandmorecontentsofC2S.
Fineness=3200cm
2
/gm
Initialsettingtime=1hrandFinalSettingtime=10hr(600min)
soundnesstestnotgreaterthan10mm(LeChateliermethod)andByautoclavetestmethod,
percent,Max0.8

20. CivilEngineeringMaterials,Er.JayantChaudhary
pg.20
Slowrateofhardening,slowstrengthdevelopment,preventshrinkageandcrackingdecrease.
Theheatofhydrationshouldnotbemorethan272and314J/gattheendof7and28days
respectively.
TherateofdevelopmentofstrengthisslowbuttheultimatestrengthissameasthatofOPC.
Tomeetthisrequirement,specificsurfaceofcement,finenessisincreasedtoabout3200
cm
2
/g.
Uses:-Massconcretingworks,hightemperatureplaces,Dam,etc.
8.PortlandPozzolanaCement(PPC)
Portlandcement+pozzolanicmaterials+finergrinding.
Pozzolana(siliceousmaterial)+Lime(Ca(OH)2)=Pozzolana-limecompound(cementitious).
Lowrateofstrengthdevelopment,decreaseinearlystength,lowheatofhydration,chemical
resistance,Offergreaterresistancetoexpansion,aggressivewater.
Fineness=3000cm
2
/gm
Initialsettingtime=30minandFinalSettingtime=10hr(600min)
soundnesstestnotgreaterthan10mm(LeChateliermethod)andByautoclavetestmethod,
percent,Max0.8
Thedryingshrinkageshouldnotbemorethan0.15%
Uses:-Ithaslowheatevolutionandisusedintheplacesofmassconcretesuchasdams
andinplacesofhightemperature.Massconcretingworks,marineworks.
9.QuickSettingCement
ThiscementisfinerthanOPCandGypsumisnotused.
Gypsumfreecement.Thequantityofgypsumisreducedandsmallpercentageofaluminium
sulphate(Al2(SO4)3)isadded.
Initialsettingtime=5minandFinalSettingtime=30min.
Rapidhardeningcementdevelopshigherrateofgainofstrengthwhilequicksettingcement
setsquicklyonlyanditsrateofgainofstrengthissimilartoordinaryPortlandcement.
Itisusedwhenconcreteistobelaidunderwaterorinrunningwater.
Itisusedmostlyinunderwaterconstructionwherepumpingisinvolved.Useofquicksetting
cementinsuchconditionsreducesthepumpingtimeandmakesiteconomical.
Quicksettingcementmayalsofinditsuseinsometypicalgroutingoperations.
10.AirEntrainingCement
Vinsolresinorvegetablefatsandoilsandfattyacidsorotherairentrainigagentareground
withOPC.
Air-entrainingadmixturesfacilitatethedevelopmentofasystemofmicroscopicairbubbles
withinconcreteduringmixing.
Itisbeneficialtouseairentrainedconcretewhenplacingconcreteinareaswithfreeze-thaw
conditions.Freeze-thawconditionsoccurwhenthetemperatureofanenvironmentfluctuates
betweenabovefreezingtemperaturesandbelowfreezingtemperaturesandprotectsfrom
cracksanddamageofconcrete.
12.WhiteCementandColouredCement
Whitecement=Frompurewhitelimestone(chalk)+clay(freefromoxidesofiron)
Sodiumaluminofluorideisaddedduringburninginclinkerwhichactsasacatalystinplaceof
iron.
Colouredcement=whitecement+5-10%colouredpigment
Itdriesquickly.Hassuperioraestheticvalue,Floorfinish,plasterwork,ornamentalworketc.

21. CivilEngineeringMaterials,Er.JayantChaudhary
pg.21
13.WaterRepellantCement(HydrophobicCement)
OPCclinker+0.1%Oleicacidorstearicacid.
Theseacidsformathin(monomolecular)filmaroundthecementparticleswhichpreventthe
entryofatmosphericmoisture.
Thespecificsurfaceofhydrophobiccementshouldnotbelessthan350m
2
/kg.
Theweakpointsofhydrophobiccementareitssmallstrengthgainduringtheinitialperiod
becauseofthehydrophobicfilmsoncementgrainswhichpreventtheinteractionwithwater,
butits28-daystrengthisequaltothatofordinaryPortlandcement.
Uses:-Inbasements,watertightstructure.
STORAGEOFCEMENT
Portlandcementiskeptinsacksof0.035m
3
(50kg)capacityforlocaluse.Thesearestoredfor
shortperiodoftimeinairtightroomavoidingmoistureanddampness,atsomedistancefromwalls
andatsomeheightfromfloors.Thestackshouldbecoveredwithsuitablecoveringstoavoid
circulationofairthroughthestackandnotmorethantenbagsshouldbestackedoneoveranother.