Cement is a powdered hydraulic cementitious building material. After adding water and mixing to form a plastic slurry, it can cement sand, bricks, stones and other building materials. Not only can it harden in the air and increase its strength, but it can also harden in water and increase its strength. Its production process is generally "two grinding and one burning". Several raw materials and fuels are mixed in a certain proportion and then ground into raw materials called raw materials in a mill, which are then calcined in a kiln. The burned materials are called clinker. The clinker is then mixed with an appropriate amount of gypsum and mixed materials and ground into cement in a mill. According to the raw material manufacturing method, it is divided into wet method and dry method (semi-dry method). The wet method is to add water to the raw materials and grind them into raw meal slurry in the mill; the dry method is to dry the raw materials and then grind them into the mill to form raw meal. pink. According to the form of calcining kiln, it can be divided into vertical kiln and rotary kiln. The classification and naming of cement are as follows:
1. According to its use and performance:
(1) General cement: Cement used in general construction projects is called general cement. It is named after the name of the main hydraulic minerals it contains plus the name of the mixed material. It is widely used and has the largest output. Such as: ordinary Portland cement, slag Portland cement, mixed Portland cement, etc. raw cement
(2) Special cement: Special cement is named after its special use. Use it within a specific range to give full play to its characteristics and achieve good results. For example: oil well cement specially used for oil wells, road cement specially used for building roads, etc.
(3) Characteristic cement: named after the main hydraulic mineral name of cement plus the main characteristics of cement. It is not proprietary and can be used whenever needed within the scope of the applicable features. Its mineral composition is diverse, including silicate, aluminate, sulfoaluminate, clinker-free, etc., and of course its properties are also different. Such as: fast-setting Portland cement, low-heat slag Portland cement, expanded sulfoaluminate cement, pozzolana cement, etc.
2. According to the main hydraulic material, it is divided into five types: Portland cement, sulfoaluminate cement, fluoroaluminate cement, pozzolanic cement and other active materials as the main components.
3. According to the technical characteristics of the length of time the cement strength is formed, it is divided into: rapid hardening and ultra-fast hardening.
4. According to the heat of hydration, it is divided into two categories: medium heat and low heat.
5. According to the sulfate resistance performance, it is divided into two categories: sulfate resistance and high sulfate resistance.
6. According to the expansion after hardening, it can be divided into two categories: expansion and self-stress.