Portland cement

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Sample of old Portland cement.

Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of most construction materials, such as concrete or mortar. It can also be used as a desiccant, though its effectiveness varies.

Properties

Chemical

Portland cement reacts with water forming various hydrates that harden into a solid mass. The reaction process is fairly complex.

Physical

Portland cement is a white-gray to slight bluish-gray solid fine powder. It is insoluble in water and all solvents, but will react with the former to form a very hard solid mass. It has an average density of 1.506 g/cm3[1], with a specific or (relative) density of 3.15[2].

Availability

Portland cement is sold by most construction and home improvement stores, usually in large bags.

Preparation

Since the production process is extremely energy intensive and is cheaply available in bulk, Portland cement is best purchased rather than made.

Projects

  • Construct stuff
  • Dry solvents (not very effective)
  • Immobilize toxic wastes

Handling

Safety

Portland cement is caustic, and contact with naked skin will cause strong dehydration and even chemical burns. Cement powder is a strong irritant and exposure may harm the eyes, nose and lungs. As it made directly from mineral sources, with no purification, Portland cement may contain hexavalent chromium which is carcinogenic and due to its fine form, it will also have lots of crystalline silica which is also hazardous to health. Traces of heavy metals, like lead and cadmium may also be present, depending on the manufacturer and mineral source of raw materials.

Objects made of cement/concrete must never be heated with a strong flame, as they will spall violently, sending sharp pieces flying in air which may cause serious injuries. As such, both Portland cement and concrete are unsuitable for making ovens and kilns, and instead refractory cement must always be used.

Storage

Portland cement is best stored in dry places, away from any moisture, preferably in sealed bags.

Disposal

Portland cement should be mixed with water (as well as sand) and left to cure, before disposal. As the final product is just plain concrete, which is generally not dangerous to environment, it can be dumped almost anywhere.

References

  1. http://www.rfcafe.com/references/general/density-building-materials.htm
  2. http://www.aso-cement.jp/en/products/product_ordinary.html

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