Cement is a finely ground powder, which, when mixed with water, forms a hardening paste of calcium silicate hydrates and calcium aluminum hydrates. Cement is used in mortars (to bind together bricks or stones) and concrete (bulk rock-like building material made from cement, aggregate, sand, and water). Most of the cement produced is used for making concrete.
Of the types of cement produced, Portland cement is most commonly used for concrete production. By modifying the raw material mix and, to some degree, the temperatures in the manufacturing process, slight compositional variations can be achieved to produce Portland cements with slightly different properties. In the U.S., the different varieties of Portland cement are described in the American Society for Testing and Materials (ASTM) Specification C-150-07 .
Portland cements are usually gray in color, but a more expensive white Portland cement can be obtained by processing raw materials with low contents of iron and transition elements. In addition, small volumes of specialty cements are also manufactured including blended cement (Portland cement mixed together with blast furnace slag or other pozzolan materials), pozzolan-lime cement, masonry cement, and aluminous cement .
Since Portland cement accounts for approximately 95% of the U.S. cement industry's total production , the costs and trends of this industrial sector can be adequately captured by describing the market processes associated with production, distribution, and use of Portland cement. In the remainder of this chapter, "cement" is synonymous with "Portland cement."
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