Portland Cement Type I It is also called Ordinary Portland Cement, used in all structural projects which do not require exposure to sulphuric acid or underground water. It is also the most-used cement in the present market. Portland Cement Type II With less heat of hydration compared with Portland Cement Type I as well as low alkali content and moderate sulphur resistance, the product is used in large-size structures and able to prevent cracks and erosions caused by sea water, salt, and alkali. The general uses are described below： Underground foundation project: Basement of high-rise buildings, tunnels, and underpasses. Mass concrete project: Bridges, dams, reservoirs, and valve foundation structure. Projects that are subject to erosion by sea water and sea wind: Wharfs, moles, sinkers, and other harbor project. Clinker In the manufacture of Portland cement, clinker occurs as lumps or nodules, usually 3 millimetres (0.12 in) to 25 millimetres (0.98 in) in diameter, produced by sintering (fused together without melting to the point of liquefaction) limestone and alumino-silicate materials such as clay during the cement kiln stage. Ground granulated blast-furnace slag The ground granulated blast-furnace slag (GGBFS) of our company is mainly used in harbor constructions, underground structures, civil water conservancies, roads, bridges, and high-rise buildings, etc. Gypsum The main component is calcium sulfate and can be divided into natural gypsum and chemical gypsum. We are now exporting natural gypsum. Silica Sand Silica sand is mixed with clay and other materials to make bricks. It is the main material in most concrete mixtures, and is frequently used as filler in many other aggregate paving products. Foundry sand has a high silica content, which is good for use in hot mix asphalt and Portland cement.