Cement is generally divided into ordinary Portland cement, Portland cement with mixed materials and special cement. Ordinary Portland Cement: By limestone, clay, iron ore powder in proportion to grind and mix; at this time the mixture is called raw material. Then it is calcined. The general temperature is about 1450 degrees, and the calcined product is called clinker. Then the clinker and gypsum are ground together and mixed proportionally, which is called cement
Portland cement with mixed materials is to add other materials in ordinary Portland cement according to proportion and certain processing procedures to achieve special effects, such as slag cement, pozzolanic Portland cement, fly ash Portland cement, composite Portland cement and so on. The raw materials of these cement are more active or inactive than those of ordinary Portland cement.
Special cement has some differences in material stage and production process; for example, high alumina cement
(aluminate cement) is made of bauxite and limestone, which are calcined to produce clinker and then ground to aluminate cement
Others have some characteristics, such as white cement, which is mainly used for decorative engineering. The materials are pure kaolin, pure quartz sand and pure limestone, which are calcined at the appropriate temperature.