Term: Cement clinker
– Composition and preparation:
– Portland clinker consists of four minerals: alite, belite, tricalcium aluminate, and calcium aluminoferrite.
– Raw materials for clinker-making are usually limestone mixed with clay or silicon dioxide.
– The second raw materials used can include clay, shale, sand, iron ore, bauxite, fly ash, and slag.
– Clinker is produced by heating raw materials in a rotary kiln at high temperatures.
– Special cements require limiting tricalcium aluminate formation.
– Uses:
– Portland cement clinker is ground to a fine powder and used as a binder in various cement products.
– It can be combined with other materials to produce different types of cement following specific standards.
– Clinker is an ingredient in artificial rock compositions like pulhamite.
– It can be stored for several months without quality loss and is traded internationally.
– Manufacturers grind clinker as an addition to their own clinker at cement plants.
– Clinker grinding aids:
– Gypsum is added to prevent flash settings and aids in grinding.
– Organic compounds like triethanolamine are used as grinding aids.
– Other additives such as ethylene glycol and oleic acid can also be used.
– Clinker minerals hydration:
– Clinker minerals react with water to form hydrates and set as concrete.
– Hydration of cement paste requires water and continues to develop strength.
– Water is essential for hardening, and desiccation must be prevented to avoid cracks.
– Traditional methods like wet burlap or curing compounds are used to prevent desiccation.
– Contribution to global warming:
– Cement production contributed about 8% of global carbon emissions in 2018.
– Most emissions in the manufacturing process are from clinker production.
Cement clinker is a solid material produced in the manufacture of portland cement as an intermediary product. Clinker occurs as lumps or nodules, usually 3 millimetres (0.12 in) to 25 millimetres (0.98 in) in diameter. It is produced by sintering (fusing together without melting to the point of liquefaction) limestone and aluminosilicate materials such as clay during the cement kiln stage.
