Nowadays, it is indispensable in most concrete structures. This is the reason why we’ve put together this informative article on Portland cement in order for you to know everything about it.
What is Portland Cement?
Portland cement constitutes a finely ground powder, formed mainly by calcium silicates and, to a lesser extent, by calcium aluminates.
When mixed with water, it forms a paste that sets and hardens at room temperature.
It is also known as “hydraulic cement”, because it is capable of setting and hardening when mixed with water, because the chemical reaction between the two creates a material with excellent binding properties.
“It is also known as” gray cement.”
It is the type of cement most commonly used in construction. However, in the beginning it was not so due to the complex procedures in order for it to harden made production more expensive. Nevertheless, technological advances have allowed it to be manufactured rapidly and on a global scale.
The history of Portland cement
Do you know when Portland cement was first talked about?
It was in 1824, when Joseph Aspdin and James Parker patented this mixture. It was given the name Portland because, once it had set, it obtained a very similar colour to Portland stone, a limestone quarried on the Portland Channel coast, located in Dorset, in southern England.
Joseph Aspdin’s son, William Aspdin (1815-1864), started the production of Portland cement near London, at a factory in Rotherhithe in 1843. William Aspdin is considered the first modern producer of Portland Cement.
“Both in Germany and in France the production of Portland Cement began in 1850.”
The first Spanish Portland cement was made in Asturias. By 1909, 100.000 tons of Portland cement were produced and in 1940, production reached 400,000 tons.
Uses of Portland Cement
Portland Cement can be used for all kinds of constructions as it is compatible with practically all conventional construction materials. It’s a very versatile and high-quality product.
It is used to make concrete blocks, pavers, bricks, and to build reinforced concrete projects or structures that require a rapid removal of formwork.
“Being so strong and durable has made Portland cement a favorite.”
These are some of its most common uses:
- Stairs, fountains, benches, wastebins, planters and public stairs.
- Columns, telephone poles or streetlights.
- Roads, paths, sport courts.
- Large-scale civil works (piers, tunnels, buildings, bridges, dams.).
- Cement mortar for masonry work.
- Cement grout to fill cracks in concrete works.
One of the greatest examples of the use of Portland cement can be seen in the Parliament of London.
Types of Portland Cement
We are going to identify the 5 types of Portland cement and describe the chemical and physical characteristics of each one of them.
Known as general-purpose cement. It is obtained by mixing plaster with Clinker. It is used in many industrial and civil constructions (floors, structures, houses, etc.).
It is used on most projects, unless construction specifications advise otherwise.
Favorable factor of this type of cement: its initial resistance and shorter casting time.
It is a modified cement, which is very useful in constructions that require a large amount of concrete (for example, a dam) or that require resistance to the attack of sulfates or chlorides (works that are in contact with water, for example, as mentioned above, a dam).
We can also find this cement used to build bridges or concrete pipes.
The Portland type II acquires its resistance slower than the type I, although it ends up matching it. Among its main characteristics, we can highlight its resistance to degradation and corrosion. This means we do not have to worry about the construction’s constant and exhaustive maintenance to extend its useful life.
It offers a very high initial resistance, and increases as the days go by. It takes 7 days to achieve type I resistance and 28 days for type II resistance.
It is used for emergency constructions or prefabricated elements. We could say that it is highly recommended in cases in which we need accelerated resistance.
“It is very similar to Type I Portland Cement, except that the particles are much finer.”
This cement type is known for its low heat of hydration, so it is used in works that do not require much initial resistance.
It is used in large concrete constructions such as tunnels or dams.
It reaches its optimum resistance after 30 days. However, the strengthening procedure continues slowly, without stopping.
It is used in the construction of works or elements that need a strong resistance to alkali and sulfate attack (pipes, slabs, sewers, port infrastructures, etc.).
To achieve this, it is necessary to reduce the amount of tricalcium aluminate is reduced from its composition due to its vulnerability to sulfates.
In our opinion, regardless of the type, Portland cement is synonymous to quality and safety.
Portland Cement Qualities
These are some of the qualities that have made it one of the most used materials in all kinds of building works.
When mixed with water, it reacts chemically until it hardens. It’s capable of curing in humid conditions and at room temperature.
It is as durable as stone. Even through harsh weather conditions such snow or rain, cement can maintain its shape, volume and performance.
Once set, it is practically impossible to break its bond with other materials such as rock, gravel, steel or brick.
If calculated correctly, when building ceilings, walls, cement is an excellent insulator against noise.
Manufacturing phases of Portland Cement
Portland cement is not just made by mixing a group of materials. It requires a process that includes a series of complex stages that we will explain bellow.
1. Obtaining raw materials
There can be no manufacturing process without the raw materials (limestone). These are usually obtained from quarries and then transported to a factory.
2. Classification and preparation of raw materials
At the factory, the size of the limestone and clay is reduced, until it is between 5 and 10 mm.
The crushed limestone and clay are mixed together. This is done by using cement mills or conveyor belts, in order to reduce its size to a diameter of 0.5 mm.
Once we have the homogeneous mixture, we take it to high temperature ovens (about 1450ºC-1600ºC). This heat supply must be uniform and constant.
Whilst in the rotary kiln, the components of the mixture melt and form granules of 1 to 3 cm in diameter, known as clinker.
Due to the high temperatures obtained in phase 4, we must cool the material to be able to work with it.
6. Incorporation of final aggregates and milling
Once the clinker has cooled, we proceed to mix it with the plaster. The mixture is ground and Portland cement is created.
Conclusions on our Portland Cement article
Portland cement was invented in 1824, but throughout history there have been many, many mixtures that have resulted in all kinds of cement.
It is basically just another material used in in concrete constructions, you may know it more as “gray cement”, present in many public architectural elements. That is why we wanted to explain in this article where the concept “Portland” came from.
It offers spectacular qualities (adhesive, durable, insulating, hydraulic, etc.), which make it ideal to use in large projects (bridges, dams …).
Its manufacturing process, despite being fully automated, requires differentiated phases that demand specific temperatures, diameters and materials to achieve the perfect product.
We hope this article has answered your questions!