Cement

Cement, better known in industry as Portland cement, is a major ingredient in concrete. Mixing Portland cement with different kinds of aggregate - crushed limestone, crushed sandstone, sand and gravel, etc. (see the section on 'aggregate') - and water creates concrete. The Portland cement bonds (or cements) aggregate materials together, making an artificial conglomerate. Everyone notices concrete just about everywhere they go! Often miscalled cement, concrete is a cost effective building material that is durable, resistant to weathering, and nearly impermeable. Concrete, and therefore cement, is the most common construction material in the world.

The term Portland cement comes from Portland stone, a stone used for construction in England. But actually, cement is made by combining limestone (for calcium), shale and/or clay (for alumina and silica), sand (for silica), and iron (Figure 1). A rotating cement kiln (Figure 2, courtesy of LaFargeHolcim) fuses these ingredients at high temperature (1,450 °C, 2,640 °F) making clinker, pea-size to golf-ball-size lumps (Figure 1). Grinding reduces clinker to a fine powder to which small amounts of gypsum are added (Figure 1). Gypsum slows down the reaction when water is mixed with cement, allowing an operator to work it before it sets hard into concrete.

Cement production occurred in Oklahoma even before statehood. Readily available abundant raw materials plus abundant energy sources of natural gas and coal helped to develop the cement industry early in the state. Today there are three cement plants operating in Oklahoma. According to the Portland Cement Association, these have a production capacity of 1.7 million metric tons per year, generating $466.8 million in cement- and concrete-related revenue to the state (2015 figures). Typically, cement manufacture contributes about one third of Oklahoma’s industrial mineral value.

How Concrete is Made from the Portland Cement Association

How to Make Concrete from Irving Materials, Inc.

Cement Making Process (Interactive Animation) from the Portland Cement Association