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: Taylor, 1997

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