Clinkers are often regarded as a staple in the construction industry. They play an integral role in ensuring that every structure that is built with cement is compositionally sound. That said, clinkers are vital for building dependable and long-lasting structures.
To better understand what a clinker actually is and why it’s so important in the first place, let’s go everything you need to know about it:
What is clinker?
Clinker is a type of nodular material that is produced throughout the kilning stage during the cement production process. It is used as a binder in most, if not all, cement products.
Generally, the lumps or nodules of clinker are visually similar to that of pebbles, with the exception that they fall anywhere between three to 25 millimetres in diameter and are dark grey in colour. The binding material is produced by heating both limestone and clay up to the point of liquefaction (which is anywhere between 1400°C and 1500°C) in a rotary kiln. When it is added to gypsum to control the setting properties of cement and reinforce compressive strength and ground finely, clinker produces a higher-grade cement.
When it comes to storage, clinker can be housed in dry conditions for extended periods of time without posing any risk to its quality. Thanks to the ease of storage, the integrity of material quality, and the wide range of benefits that clinker has, it is traded all over the world and utilized by cement manufacturers when their raw material supplies are scarce.
What is a clinker composed of?
Inspecting the composition of clinker can be done in one of two different approaches, namely: mineralogical analysis through the use of petrographic microscopy or x-ray diffraction analysis through chemical analysis. The latter option, more often than not, is chosen because of its ability to accurately determine the composition of clinker, mainly through x-ray fluorescence spectrometry.
A clinker is comprised of four main components, namely:
- Alite: approximately tricalcium silicate (typically about 65 per cent of the total)
- Belite: approximately dicalcium silicate (typically about 15 per cent of the total)
- Aluminate: approximately tricalcium aluminate (typically about seven per cent of the total)
- Ferrite: approximately tetracalcium aluminoferrite (typically about eight per cent of the total)
The various types of clinker
Clinker comes in various types that are suited for a wide array of purposes and can be easily dichotomized according to its material composition. Each type of clinker also varies depending on what type of cement it is produced for as a means to adhere to specific tendencies or properties that are within the cement itself. Here are a few common types of clinker:
- Sulfate-resistant clinker: This type of clinker contains 76 per cent alite, 5 per cent belite, two per cent tricalcium aluminate, 16 per cent tetracalcium aluminoferrite, and one per cent free calcium oxide. It is worth noting, however, that its production has taken a downturn in recent years, so it may be quite scarce.
- Low-heat clinker: On the other hand, low-heat clinker contains 29 per cent, 54 per cent, two per cent tricalcium aluminate and 15 percent tetracalcium aluminoferrite. Just like sulfate-resistant clinker, low-heat clinker is scarce because it is no longer produced as a result of modern alternatives.
- White clinker: White clinker contains 76 per cent alite, 15 per cent belite, seven per cent tricalcium aluminate, no tetracalcium aluminoferrite, and two per cent free lime—but this composition can also vary widely. This particular type of clinker gets its namesake from the fact that it produces white cement, which is essentially used for aesthetic purposes.
Final words
Clinker has been proven to play an essential part in upholding the structural integrity of any structure that is composed of or partly uses concrete.
If you want to reinforce your structures with high-quality examples of clinker, get in touch with BLK Commodities today to see how we can help!