Transcript CE 5102: Introduction - Michigan Technological University

Cement Production
Portland Cement
By definition —
a hydraulic cement
produced by pulverizing
clinker consisting
essentially of hydraulic
calcium silicates, usually
containing one or more of
the forms of calcium
sulfate as an interground
addition
Source: PCA, 2003
Raw Materials Necessary for
Portland Cement Manufacture
Must Provide the Following
Calcium
Silica
Alumina
Iron
Calcium
Iron
Silica
Alumina
Sulfate
Alkali waste
Aragonite
Calcite
Cement-kiln
dust
Cement rock
Chalk
Clay
Fuller’s earth
Limestone
Marble
Marl
Seashells
Shale
Slag
Blast-furnace
flue dust
Clay
Iron ore
Mill scale
Ore washings
Pyrite cinders
Shale
Calcium silicate
Cement rock
Clay
Fly ash
Fuller’s earth
Limestone
Loess
Marl
Ore washings
Quartzite
Rice-hull ash
Sand
Sandstone
Shale
Slag
Traprock
Aluminum-ore
refuse
Bauxite
Cement rock
Clay
Copper slag
Fly ash
Fuller’s earth
Granodiorite
Limestone
Loess
Ore washings
Shale
Slag
Staurolite
Anhydrite
Calcium
sulfate
Gypsum
Source: PCA, 2003
Traditional Manufacture of
Portland Cement
Source: PCA, 2003
1. Stone is first reduced to 125 mm (5 in.)
size, then to 20 mm (3/4 in.), and stored.
2. Raw materials are ground to powder and blended.
or
Source: PCA, 2003
2. Raw materials are ground, mixed with water to form slurry,
and blended.
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
PyroProcessing
Source: PCA, 2003
4. Clinker is ground with gypsum into portland cement and
shipped.
Source: PCA, 2003
Clinker
Source: PCA, 2003
Gypsum
Grinding
Clinker is ground with
gypsum (calcium sulfate) to
produce portland cement
Fine grinding is necessary
for high early strength
– 85-95% -325 mesh (45
microns)
– ~ 7 trillion particles per
pound
Gypsum absorbs water and
prevents setting of C3A
during shipment
Source: van Oss and Padovani, 2002
Process 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 Phases
Alite or 3CaO•SiO2 or C3S
– Hydrates & hardens quickly
– High early strength
– Higher heat of hydration
(setting)
Belite or 2CaO• SiO2 or C2S
– Hydrates & hardens slower
than alite
– Gives off less heat
– High late strength (> 7 days)
Modern cements are
manufactured to be higher in
alite for early strength
Clinker Phases
Aluminate or 3CaO• Al2O3
or C3A
– Very high heat of hydration
– Some contribution to early
strength
– Low C3A for sulfate
resistance
Ferrite or 4CaO• Al2O3 •
Fe2O3 or C4AF
– Little contribution to strength
– Lowers clinkering
temperature
– Controls the color of cement
Microscopic Images of Clinker
Microscopic Images of Clinker
Alite
Microscopic Images of Clinker
Belite
Microscopic Images of Clinker
Aluminate
Microscopic Images of Clinker
Ferrite
Types of Portland Cement
ASTM C 150 (AASHTO M 85)
I
II
III
IV
V
Normal
Moderate sulfate resistance
High early strength
Low heat of hydration
High sulfate resistance
Source: Mindess, Young, and Darwin, 2004
Source: Mindess, Young, and Darwin, 2004
Source: Mindess, Young, and Darwin, 2004
Source: Mindess, Young, and Darwin, 2004