Cement: powdery hydraulic inorganic gelling material. After adding water and stirring, it will become a slurry, which can be hardened in air or in water, and can firmly cement sand, stone and other materials together.
The early lime-volcanic ash mixture is very similar to modern lime-volcanic ash cement . The concrete made with cement and crushed stone not only has higher strength after hardening, but also resists erosion by fresh water or salt water. For a long time, as an important gelling material, it is widely used in civil engineering, water conservancy, national defense and other projects.
Cement is divided into:
(1) General cement: Cement commonly used in general civil construction projects. General cement mainly refers to the six major types of cement specified in GB175-2007, namely Portland cement, ordinary Portland cement, slag Portland cement, pozzolanic portland cement, fly ash portland cement and Portland cement.
(2) Special cement: special purpose cement. Such as: Class G oil well cement, road portland cement.
(3) Characteristic cement: a cement with outstanding performance. Such as: fast hard portland cement, low heat slag portland cement, expanded sulphoaluminate cement, phosphoaluminate cement and phosphate cement.