Cement is defined in many ways as follows,
Cement, any material that hardens and becomes strongly adhesive after
Manufactured substance consisting of gypsum plaster, or Portland cement.
Portland cement hardens and adheres after being mixed with water.
History of Cement:
• The term “Portland cement” was first used in 1824 by Joseph Aspdin, a British
cement-maker, because of the resemblance between concrete made from his
cement and Portland stone, which was commonly used in buildings in Britain.
• At that time cements were usually made in upright kilns where the raw materials
were spread between layers of coke, which was then burnt.
• The first rotary kilns were introduced about 1880. Portland cement is now almost
universally used for structural concrete.
• Main ingredients used in the manufacture of cement are:
• Clay, shale
– local resources necessary: no market
• Limestone (CaCO3) and Clay are two main raw materials used for manufacturing
Portland cement clinker.
• Clays have various amount of SiO2 and Al2O3.
• In the manufacturing process of Portland cement, clinker consist essentially of
grinding the raw materials, mixing them in appropriate proportion, burning the
raw material in a kiln at a temperature of 1400-1500oC until material partially
fuses into balls known as Clinker and grinding cooled clinker together with a
small amount of gypsum rock.
• The mixture of raw material is burned in a rotary kiln.
The heart of the cement plant
• Largest moving part of any machine.
• inclined, rotates.
• up to 50m long and 5m diam.