Cement, How It Is Produced
Cement, or Portland cement, is defined as "a hydraulic cement, obtained by burning a mixture of lime and clay to form a clinker, then pulverizing the clinker into powder. The greenish gray powder is composed primarily of calcium silicates, calcium aluminates, and calcium ferrites. When mixed with water (Hydrated), it solidifies to an artificial rock, similar to Portland stone." A Portland Stone is a yellow limestone from the Isle of Portland, in Great Britain.
Historically, cement can be traced back to the early Roman Empire, and contributed to the building of the great structures of the Roman Empire. By varying the amounts and types of the same basic ingredients, cement with various properties may be obtained. By further varying the ingredients, even more differing cements are manufactured.
*"Cement manufacturing is the basic processing of selected and prepared mineral raw materials to produce the synthetic mineral mixture (clinker) that can be ground to a powder having the specific chemical composition and physical properties of cement." Cement manufacture, like many other manufacturing processes, begins at the mine, where the raw materials like limestone, silica, aluminates, feric minerals and others are obtained. Some typical materials used for calcium carbonate in cement manufacturing are limestone, chalks, marbles, marls, and oyster shell. Some typical materials used for alumina in the cement manufacturing are shale, clay, slags, fly ash, bauxite, alumina process waste, and granite. Some typical materials used for silica in cement manufacturing are sand, clay, claystone, shale, slag, and fly ash. Some typical materials used for iron in cement manufacturing are iron ores, blast furnace flue dusts, pyrite clinker, mill scale, and fly ash.
First, Type 1 cement is general cement for general use, typically the type used in construction.
Type 2 cement is still a general cement, but it has resistance to sulfates and heat of hydration.
Type 3 cement is for high strength properties in the early stages of the cement's life. I.e., immediately after curing.
Type 4 cement is used where very low heats of hydration are desired.
And Type 5 cement is used where a very high sulfate resistance is required.
In the United States, the American Society of Testing Materials, the American Association of State Highway Officials, the American Concrete Institute, the US Corps of Engineers are generally the primary driving force of the cement quality and technology standards and specifications.
Concrete is a mixture of gravel, sand and cement. Concrete is NOT cement, but it is made with cement.
* - Industrial Minerals and Rocks 4th Edition
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