Week of December 20, 2020

The Material World


Glass is basically melted sand. Modern commercial glass recipes have some other things thrown in, including recycled glass, but it starts with sand, which is mostly silicon dioxide.


Steel is basically iron with a hint of carbon. To get the properties which give steel its advantages over iron, though, the carbon must be added in just the right amount and conditions.


Concrete is basically a mixture of rocks, cement, air, and water. Cement, in turn, is a mixture of lime, silica, alumina, and gypsum, almost all from natural sources like limestone, chalk, coral and shell deposits.


Plastics typically come from oil. Oil is packed with carbon, the basic building block of the polymers in plastic and the great varieties of plastic types which can be synthesized. However, because plastics don’t react chemically with most substances, they also do not decompose or decay easily, causing environmental problems.


Asphalt is combination of a little “asphalt cement,” a viscous petroleum tar-like substance which binds together the aggregate, or gravel and sand of various sizes. This slurry is then usually flattened smooth, as for roads.


Traditionally, bricks are wet clay from the ground heated and dried in a hot kiln. Modern bricks can have different ingredients depending on their purpose, and may contain sand, lime, concrete, aluminum oxide, and fly ash (a coal burning by-product).


Plaster is typically made from lime or gypsum with sand and water and has been used in building and sculpting since antiquity.