A number of special cements are now available to the concrete construction industry. Each type serves a specific function in terms of application, performance and durability. Although each may be used by itself to answer a special construction need, some may be used with other standard or special types to achieve special esthetic or functional objectives. The following descriptions of various special cements deal only with the basic characteristics of the cements and their applications. Air-entraining cements are useful where careful control is not practical of air entraining concrete is not practical, air entraining cements are useful to insure that at least a significant portion of the required air content will be obtained. Blended hydraulic cements come in three kinds: portland blast-furnace slag cement, portland pozzolan cement, and slag cement. These cements resist sea attack and/or to replace portland cement in the mix for economy. Natural cements are made by finely grinding calcined argillaceous limestone. It is used for making masonry motors because of the higher water retention. Masonry cements are mostly mixtures of portland cement, air-entraining additives and finely ground supplemental materials. They are formulated primarily for their ability to impart to masonry mortars workability, water retention an plasticity. White cement is made much like portland cement except white cement has a lower iron and manganese content. Is usually used for mixing with color for color concrete. Buff colored cements usually depend on certain raw materials for the color of the cement. Regulated-set cement is a hydraulic cement related to portland cement but containing an additional rapid-setting, rapid-strength producing ingredient. Except for the regulated-set and early strength properties, which are of significance during the first few hors in particular, test show the physical characteristics of concrete made with regulated-set cement to be similar to comparable mixes made with standard portland cement.