Definition

Clinker is the basic input in the production of all the cement types CEM I to CEM V. Clinker is a pebbly rock-like substance that is made by heating limestone and other raw materials to a very high temperature in a kiln. Though limestone is the main material necessary for the production of clinker, other substances are involved, too.

Limestone	83%
Sand	5%
Gypsum	4%
Shale	3%
Clay	3%
Iron material	1%
Other	1%

Storage

Clinker, if stored in dry conditions, can be kept for several months without appreciable loss of quality. Because of this, and because it can easily be handled by ordinary mineral handling equipment, clinker is traded internationally in large quantities.

Typical Composition

Element	Typical Content
Lime Saturation Factor	93.00 – 98.00
Silica Module	2.10 – 2.60
Alumina Module	1.05 – 1.30
C3S	58.00 – 65.00%
C2S	11.00 – 16.00%
C3A	4.00 – 7.50%
C4AF	11.00 – 16.00%
SO3	0.30 – 0.95%
MgO	1.00 – 2.00%
Insoluble Residue	Max. 2
Loss On Ignition	Max. 5
Free Lime	Max. 1.90
Alkali Equivalent	0.65 – 0.85%