Cement Production. Portland Cement By definition — a hydraulic cement produced by pulverizing...
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Transcript of Cement Production. Portland Cement By definition — a hydraulic cement produced by pulverizing...
Cement ProductionCement Production
Portland CementPortland Cement
By definition — By definition — a hydraulic cement a hydraulic cement produced by pulverizing produced by pulverizing clinker consisting clinker consisting essentially of hydraulic essentially of hydraulic calcium silicates, usually calcium silicates, usually containing one or more of containing one or more of the forms of calcium the forms of calcium sulfatesulfate as an interground additionas an interground addition
Source: PCA, 2003
Raw Materials Necessary for Raw Materials Necessary for Portland Cement Manufacture Portland Cement Manufacture
Must Provide the FollowingMust Provide the FollowingCalciumCalcium
SilicaSilica
AluminaAlumina
IronIron
Calcium Calcium IronIron Silica Silica AluminaAlumina SulfatSulfatee
Alkali wasteAlkali waste
AragoniteAragonite
CalciteCalcite
Cement-kiln Cement-kiln dustdust
Cement rockCement rock
ChalkChalk
ClayClay
Fuller’s earthFuller’s earth
LimestoneLimestone
MarbleMarble
MarlMarl
SeashellsSeashells
ShaleShale
SlagSlag
Blast-furnace Blast-furnace flue dustflue dust
ClayClay
Iron oreIron ore
Mill scaleMill scale
Ore washingsOre washings
Pyrite cindersPyrite cinders
ShaleShale
Calcium silicateCalcium silicate
Cement rockCement rock
ClayClay
Fly ashFly ash
Fuller’s earthFuller’s earth
LimestoneLimestone
LoessLoess
MarlMarl
Ore washingsOre washings
QuartziteQuartzite
Rice-hull ashRice-hull ash
SandSand
SandstoneSandstone
ShaleShale
SlagSlag
TraprockTraprock
Aluminum-ore Aluminum-ore refuserefuse
BauxiteBauxite
Cement rockCement rock
ClayClay
Copper slagCopper slag
FlyFly ashash
Fuller’s earthFuller’s earth
GranodioriteGranodiorite
LimestoneLimestone
LoessLoess
Ore washingsOre washings
ShaleShale
SlagSlag
StauroliteStaurolite
AnhydriteAnhydrite
Calcium Calcium sulfatesulfate
GypsumGypsum
Source: PCA, 2003
Traditional Manufacture of Traditional Manufacture of Portland CementPortland Cement
1. Stone is first reduced to 125 mm (5 in.) size, then to 20 mm (3/4 in.), and stored.
Source: PCA, 2003
2. Raw materials are ground to powder and blended.
or
2. Raw materials are ground, mixed with water to form slurry, and blended.
Source: PCA, 2003
3. Burning changes raw mix chemically into cement clinker.
Source: PCA, 2003
Source: Mindess, Young, and Darwin, 2004
Source: Mindess, Young, & Darwin, 2004
3. Burning changes raw mix chemically into clinker. Note four stage preheater, flash furnaces, and shorter kiln.
Source: PCA, 2003
Pyro- Pyro- ProcessingProcessing
Source: PCA, 2003
4. Clinker is ground with gypsum into portland cement and shipped.
Source: PCA, 2003
ClinkerClinker Gypsum
Source: PCA, 2003
GrindingGrindingClinker is ground with Clinker is ground with gypsum (calcium sulfate) to gypsum (calcium sulfate) to produce portland cementproduce portland cement
Fine grinding is necessary Fine grinding is necessary for high early strengthfor high early strength– 85-95% -325 mesh (45 85-95% -325 mesh (45
microns)microns)
– ~ 7 trillion particles per ~ 7 trillion particles per poundpound
Gypsum absorbs water and Gypsum absorbs water and prevents setting of Cprevents setting of C33A A
during shipmentduring shipment
Source: van Oss and Padovani, 2002
Process of Clinker ProductionProcess of Clinker Production
Source: PCA, 2003
Source: PCA, 2003
Source: PCA, 2003
Source: Taylor, 1997
Source: MacLaren and White, 2003
Source: MacLaren and White, 2003
Clinker PhasesClinker Phases
Alite Alite oror 3CaO•SiO 3CaO•SiO22 oror C C33SS– Hydrates & hardens quicklyHydrates & hardens quickly– High early strengthHigh early strength– Higher heat of hydration (setting)Higher heat of hydration (setting)
Belite Belite oror 2CaO• SiO 2CaO• SiO22 oror C C22SS– Hydrates & hardens slower than Hydrates & hardens slower than
alitealite– Gives off less heatGives off less heat– High late strength (> 7 days)High late strength (> 7 days)
Modern cements are Modern cements are manufactured to be higher in manufactured to be higher in alite for early strengthalite for early strength
Clinker PhasesClinker PhasesAluminate Aluminate oror 3CaO• Al 3CaO• Al22OO33
oror C C33AA– Very high heat of hydrationVery high heat of hydration– Some contribution to early Some contribution to early
strengthstrength
– Low CLow C33A for sulfate A for sulfate
resistanceresistance
FerriteFerrite oror 4CaO4CaO• • AlAl22OO3 3 • •
FeFe22OO33 oror CC44AFAF– Little contribution to strengthLittle contribution to strength– Lowers clinkering Lowers clinkering
temperaturetemperature– Controls the color of cementControls the color of cement
Microscopic Images of ClinkerMicroscopic Images of Clinker
Microscopic Images of ClinkerMicroscopic Images of Clinker
Alite
Microscopic Images of ClinkerMicroscopic Images of Clinker
Belite
Microscopic Images of ClinkerMicroscopic Images of Clinker
Aluminate
Microscopic Images of ClinkerMicroscopic Images of Clinker
Ferrite
Types of Portland CementTypes of Portland Cement
II NormalNormalIIII Moderate sulfate resistanceModerate sulfate resistanceIIIIII High early strengthHigh early strengthIVIV Low heat of hydrationLow heat of hydrationVV High sulfate resistanceHigh sulfate resistance
ASTM C 150 (AASHTO M 85)
Source: Mindess, Young, and Darwin, 2004
Source: Mindess, Young, and Darwin, 2004
Source: Mindess, Young, and Darwin, 2004
Source: Mindess, Young, and Darwin, 2004