Cement clinker is a nodular material that forms the essential core component of cement. It is produced by heating a mixture of limestone, clay, and other mineral additives in a kiln at high temperatures, typically ranging from 1,450 to 1,550 degrees Celsius (2,642 to 2,822 degrees Fahrenheit). The process of heating the raw materials in a kiln is called “clinkering,” which gives rise to the term “clinker.”
During the clinkering process, the raw materials undergo chemical reactions, resulting in the formation of new compounds, primarily calcium silicates (C3S and C2S), as well as smaller amounts of calcium aluminates (C3A) and calcium sulfates (C3S). These compounds are essential for the hydraulic properties of cement, allowing it to harden and gain strength when mixed with water.
Once the clinkering process is complete, the clinker is then cooled, ground into a fine powder, and combined with gypsum to form Ordinary Portland Cement (OPC) or other specialized cement types. The grinding process increases the surface area of the clinker particles, enhancing its reactivity with water during cement hydration.
Cement clinker is the primary building block of cement and acts as a binder that holds the aggregates (sand, gravel, etc.) together in concrete. Different types of cement can be produced by varying the proportions of raw materials and the clinkering conditions, resulting in various cement grades suitable for different construction applications.