Production.

• Position: LIFE - CYCLE STUDIES - Brief article

Modern concrete's main ingredient, cement, is most commonly produced using a method invented by Englishman Joseph Aspdin in 1824. His Portland cement (named after the limestone used in St. Paul's Cathedral and Buckingham Palace) mixes a powder of alumina, silica, lim, iron oxide, and magnesium oxide, which is then heated at temperatures up to 1,450 degrees Celsius.

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Heating and grinding the cement materials consumes an average of 4-5 gigajoules of energy per cement ton. The industry as a whole uses at least 8 billion gigajoules each year. Cement production--through cement plants' fossil-based energy consumption, the [CO.sub.2] burned off when limestone is heated, associated vehicle use, and other factors--accounts for about 6 percent of global...