Cement: powder hydraulic inorganic cementitious material. It can harden in air or better in water, and can firmly bond sand, stone and other materials together. The word cement developed from the Latin caementum and means gravel and rubble. The mixture of early lime and pozzolan is very similar to modern lime pozzolan cement. The concrete made of cemented crushed stone has not only high strength after hardening, but also can resist the erosion of fresh water or saline water. For a long time, as an important cementitious material, it has been widely used in civil engineering, water conservancy, national defense and other projects.
