Cement Production and History Quiz

Cement Overview

• Cement is a crystalline compound composed of calcium silicates and other calcium compounds possessing hydraulic properties.

Cement History

• Lime and clay have been used as cementing materials for centuries.
• Romans are credited with developing hydraulic cement, a significant advancement.
• The Romans used a pozzolan-lime cement by mixing volcanic ash from Mt. Vesuvius with lime (a method that is still used).
• The Pantheon in Rome is an example of Roman cement construction.
• Joseph Aspdin, from England, invented Portland cement in 1824.

Types of Cement

• Hydraulic cements set and harden in the presence of water by hydration of component minerals.
• Pozzolanic cements develop hydraulic properties when interacting with hydrated lime. These are siliceous materials.
• Hydraulic lime is used in specialized mortars, made from calcined clay rich limestones.
• Natural cements, sometimes called Roman cements, are made from argillaceous limestones (e.g. limestone and clay), inferior to Portland cement.

Portland Cement

• An artificial cement produced by mixing clinker with gypsum (in a 95:5 ratio).
• Portland-limestone cements: Ground limestone is added as a filler to Portland cement in amounts ranging from 6% to 35%.
• Blended cements: A mixture of Portland cement with one or more supplementary cementitious materials (like pozzolanic additives).
• Pozzolan-lime cements are original Roman cements, with a small quantity of production in the United States.
• Masonry cement: Portland cement with additives to improve plasticity.
• Aluminous cement: Made from limestone and bauxite; used in refractory applications (e.g., in furnace bricks) where fast hardening is needed.

Raw Materials for Cement Production

• Key chemical compounds in cement clinker: Lime (CaO), Silica (SiO2), Alumina (Al2O3), and Iron Oxide (Fe2O3).
• Raw materials: Limestone, marl, chalk (sources of calcium carbonate); Clay, shale, sand, iron ore, bauxite, diatomite (sources of argillaceous materials); Fly ash, bottom ash, foundry sand, metallurgical slags (waste material substitutes).
• Fly ash is a byproduct of coal combustion.

Clinker Compounds in Type I Portland Cement

• Key components and their abbreviations are outlined in the document.

Limestone Sources

• Limestone, marble, chalk, marl, coral, aragonite, oyster/clam shells, travertine, and tuff are sources of CaCO3 (calcium carbonate).
• Most industrial quality limestone is biological in origin and is composed of CaCO3 and MgCO3.
• Ideal cement rocks contain 77-78% CaCO3, 1.4% SiO2, 2.5% Al2O3, and 1.75% Fe2O3. Limestone with lower CaCO3 and higher alkalis/magnesia needs blending

Sources of Argillaceous Minerals

• Clay and shale provide alumina and silica, and iron ore provides iron.
• Other sources for silica and alumina include loess, silt, sandstone, volcanic ash, diaspore, diatomite, and bauxite.

Marketing

• Wide distribution of cement plants lowers costs for consumers.
• Other factors include delivered cost, quality, consistency, technical assistance, and sales relationships.

Cement Production

• Worldwide production data and capacity are provided.

Cement Mining Methods

• Limestone mining methods vary, typical methods include bench mining (using explosives) and underground mining (e.g., room and pillar mining) for limestone.
• Marl and chalk frequently do not require blasting.

Cement Processing

• A detailed description of cement processing steps, including quarrying, blending, proportioning and fine grinding, kilning, cooling and clinker storage and finishing grinding, and shipping systems is detailed in a flow chart.

Cement Uses

• Cement is the primary material in the manufacture of concrete and mortar.
• Current uses include buildings, transportation, waterworks, and agriculture.

Concrete Substitutes

• Materials competing with cement in the construction industry include alumina, asphalt, clay bricks, fiberglass, glass, steel, and stone/wood.
• Some materials (such as fly ash and ground granulated furnace slags) are used as partial substitutes for cement in concrete applications.

Resources

• Despite the potential for material depletion in individual companies, cement raw materials (especially limestone) are abundant geographically and shortages are unlikely in the future.