Cement Production Portland Cement By definition a hydraulic
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 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
Pyro. Processing
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 C 3 A 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: Mac. Laren and White, 2003
Source: Mac. Laren and White, 2003
Clinker Phases Alite or 3 Ca. O • Si. O 2 or C 3 S – Hydrates & hardens quickly – High early strength – Higher heat of hydration (setting) Belite or 2 Ca. O • Si. O 2 or C 2 S – 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 3 Ca. O • Al 2 O 3 or C 3 A – Very high heat of hydration – Some contribution to early strength – Low C 3 A for sulfate resistance Ferrite or 4 Ca. O • Al 2 O 3 • Fe 2 O 3 or C 4 AF – 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 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
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