If you’ve never heard of Portland cement, you might be surprised to learn that it’s one of the most important materials ever produced by human beings, created and patented by Joseph Aspdin in 1824.
Aspdin heated limestone cement powder mixed with clay in a furnace, and ground up the resulting clinker into powder. He named the substance “Portland cement” due of the similaritit holds when set to Portland stone, a kind of rock excavated on the Isle of Portland in the UK. The Aspdin cement business continued through Aspdin’s son William, popular as it was for its powerful heating. To this day, Portland cement is the most commonly used throughout the world.
Portland Cement Industry
Cement is typically produced by two processes:
The second process is basically the same, except for the fact that in the wet process the raw material is mixed with water before they are put into the kiln. All though there is little difference in efficiency between the two processes, the wet process has the disadvantage of CO2 emissions and fuel consumption to evaporate the water. Most of the cement making process produced is done so using the preferred dry process.
There are five stages involved in the manufacture of cement using a dry process, which is discussed below.
Crushing and Grinding: The raw materials such as limestone and clay, which is obtained from the mine, is crushed to a fine powder form.
The proportion of raw materials: The raw materials are crushed and mixed in the correct proportions to form what is called “raw food” or “kiln feed”.
The crude feed in r is heated in rotary kilns: The “raw food” is introduced at the higher end of the rotary kiln with a conveyor and heated to about 1400-1500 degrees Celsius.
Formation of clinker: The new substance that emerges from the kiln is known as the ‘clinker’.
Grinding clinker with gypsum: The cement clinker is normally ground inside a ball mill to form a fine powder. A small amount of gypsum used in the milling process is to control the setting properties of concrete when mixed with water. The end product of this process is called “Portland Cement”.
Cement then is produced so finely that it almost completely passes through a 0.075mm sieve. The cement is then packaged and transported to various construction projects and suppliers across the country. For Concrete Pumping, visit a site like https://www.monstermixconcrete.co.uk/concrete-pumping/
Variations of Portland Cement
Aside from the above methods producing “general purpose” Portland cement used for construction purposes, there are other uses. Other modifications of Portland cement are also produced in so as to meet differing construction goals / needs.
Sulfate-Resisting Portland Cement: The presence of sulphate can cause concrete to get damaged and crack, expanding the concrete. The use of sulfate-resisting Portland cement is to prevent sulfates from entering the surface thereby increasing longevity.
White Portland Cement: This cement type intended for use in architectural purposes in which there is a need for white concrete. It differs from grey cement and is produced by controlling the use of ferrites.
Quick-Hardening Portland Cement: Similar to conventional Portland cement, except that it consists of more finely ground particles to facilitate a rapid reaction with water. It is used when there is a need for rapid strength and/or structure.
Low Heat Portland Cement Hydration: This type of cement takes much longer to grow in strength than other types of cement and would be used in structures such as dams. It is produced by special request for large projects.