In the general sense, a cement (Latin caementum) is any material with adhesive properties. The term cement is also commonly used to refer more specifically to powdered materials which develop strong adhesive qualities when combined with water. These materials are more properly known as hydraulic cements. Gypsum plaster, common lime, hydraulic limes, natural pozzolana and Portland cements are the more common hydraulic cements, with portland cement being the most important in construction.
History
Hydraulic cement was first invented by the Egyptians, and later reinvented by the Greeks and Babylonians, who made their mortar out of lime, much harder than the Roman mortars. Later, the Romans produced a good cement from pozzolanic ash.
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Production
Portland cement was patented in England by Joseph Aspdin in 1824.
Limestone is mixed with other additives containing iron, alumina and silica in definite proportions. This mixture is finely ground in a raw mill. The resultant raw mix is burned in a rotary kiln (a rotating sloped furnace) at temperatures around 1 400 degrees Celsius to form clinker. The clinker nodules are then ground with about 3 % gypsum to produce cement with a fineness typically of less than 90 micrometres.
Properties
Chemical properties
Tricalcium Silicate,
Dicalcium Silicate,
Tricalcium Aluminate,
Tetracalcium Aluminoferrite,
Gypsum
Geology
In geology, the term is used to refer to the fine-grained minerals which bind the coarser-grained matrix in sedimentary rocks. Such cements are typically composed of calcite, quartz or clay minerals.
Companies in this market
- Texas Industries Inc.
- Eagle Materials Inc.
- Vulcan Materials Co
Another meanings
Cement is also the name of Chuck Mosley's post Faith No More band. Additionally, CEMENT is an acronym for Computer Enhanced Multiple Exposure Numerical Technique in which multiple pictures of the same subject matter are "cemented" together to attain increased picture resolution or for artistic visual lightspaces.
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