Clinker

Clinker – Definition
Clinker is a solid, dark-gray nodular  material produced as an intermediate product in the manufacture of Portland cement.
It is formed by heating a precise mixture of limestone (calcium carbonate) and clay (silica, alumina, and iron oxide) in a rotary kiln at temperatures between 1400°C and 1500°C.

When cooled and ground with a small amount of gypsum, it becomes cement.

Main Characteristics
Appearance: dark gray, granular, marble-sized nodules.

Composition: mainly tricalcium silicate (C₃S), dicalcium silicate (C₂S), tricalcium aluminate (C₃A), and ferrite (C₄AF).

Density: around 3.15 g/cm³.

Moisture sensitivity: stable under dry conditions, non-reactive until ground.