1. A material or a mixture of materials (without aggregate) which, when in a plastic state, possesses adhesive and cohesive proper- ties and hardens in place. Frequently, the term is used incorrectly for concrete, e.g., a “cement” block for concrete block. See also portland cement.
2. A calcined combination of lime- stone and clay, combined with an aggregate that reacts chemically when water is added; after this reaction occurs, the mixture hardens in place as it dries, resulting in a stonelike material. Although the ancient Romans developed a cement that could harden under water (called hydraulic cement), there was little information in modern times on how to produce such a cement until the mid-1700s when experiments in England led to the development of a cement that could set quickly, in or out of water.
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