Serious Materials Rocks
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A version of this article appears in the July/August 2008
issue of Home Energy Magazine.
July 01, 2008
Gypsum. It’s not just for Twinkies. The mineral, a semi hydrous form of calcium sulfate, with many uses from Plaster of Paris to Chinese Medicine and even Twinkies, is mined all over the world. It’s most popular use is in the most prevalent of the building materials, sheetrock, or drywall. Invented in 1917, when energy was cheap, sheetrock is like other energy-intense concoctions of its time, a miracle invention that revolutionized home-building, making it much easier than prevailing practices. But its manufacture owes a full 25% to 50% of its costs to energy. It joins its sister materials glass, steel, and cement in being a major part of the problem of greenhouse gases. To make sheetrock, gypsum is heated in large natural gas kilns to about 300°F (coughing lots of C02 into the sky), and then dried (again, using natural gas). Additives are mixed in such as fiberglass and mold repellants, and then paper backing is placed on one side of the dry plaster, as well as the manufacturer’s stamp. Considering its prevalence in the building industries, and the building industries’ prevalence in worldwide energy consumption, the evolution of drywall could play a major role ...
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