10 November 2020
The real big step towards what we know as modern cement today, and thereby leading to what we use as modern concrete, was the invention of Portland Cement. This compound is generally what modern builders and concreters use today.
Portland Cement
In 1824, a man by the name of Joseph Aspdin built upon (no pun intended) John Smeaton’s formula (read the previous article regarding Mr Smeaton and the Eddington Lighthouse). The method actually resembles Smeaton’s quite closely, also using clay and limestone that is first fired into clinkers (bricks of the material) and then ground down into a fine powder.
Mr Aspdin combined limestone with clay to form the clinkers and added a small amount of gypsum (a material found in plaster and chalk etc). This gave the powder a paler colour and the name of the formula (ie Portland) was derived from the original quarry that some of the original materials were sourced from.
Today there are more variations on the formula that allow workers and contractors to vary their method depending on the location and purpose of the concreting required, however the basic formula contains four main ingredients (ignore the sciency talk for a bit we just want to get it right for those who care)….
Dicalcium silicate (2CaO · SiO2)
Tricalcium silicate (3CaO · SiO2)
Calcium aluminoferrite (4CaO · Al2O3Fe2O3)
Tricalcium aluminate (3CaO · Al2O3)
We know, our heads hurt to, but it’s these four simple ingrediants that give concrete it’s rigidness and strength, but also allow it to be formed in a slurry with water to make it malleable enough to work, pour and mould into any shape you want.
Another big change was the availability of the material as one of the benefits of modern technology as man settle into the industrialised age was that this could all be done on an industrialised and mass produced level. Mining of the raw material was still very much man powered but aided with the use of machines, and the use of explosives made getting access to materials quicker. The transport of the raw materials also proved faster with rail networks which could then be sent to manufacturing plants. Larger and improved furnaces could fire the clinkers and the machines could be used to ground down the cement to a more fine and consistent powder in less time. Mixing with machines also made it more consistent and allowed larger batches as well.
While Mr Aspdin did setup his own plant to mass produce the material, the uptake of the new formula was originally slow, and never really reached mass popularity in his lifetime. In England however, the man helped supply concrete for building the Thames River Tunnel, a massive project for the time. After his death, it would be used to build London’s sewer system in starting in 1859.
The formula was eventually exported to the United States of America in 1868 and after peak exportation all most twenty years later, America started producing their own. Before much longer, the formula and methodology for making concrete would rely on the Portland method worldwide wherever the materials were available.
Concrete Today
Looking around, it is hard not to see concrete everywhere. Most buildings, whether you can see it or not, rely on concrete. Foundations, driveways, footpaths all contain concrete thanks to a long history of human trial and error.
Although there were many breakthroughs in regards to it’s formula, it’s use continued to change and improve as technology and ideas allowed better building techniques and management.
In 1849 a guy by the name of Joseph Monier came up with the idea of reinforced concrete. This used steel rods or shafts, or sometimes beams to create an even stronger structure.
In 1854 the first home in England was built with concrete, identifying a mark where it became both affordable and manageable by common builders and access to the general public.
In 1889 the first reinforced bridge made out of concrete was built, proving that it could be used to span lengths and gaps, whereas in 1891 the first street made completely of concrete was poured, vastly improving the old pavered and cobbled streets at the time. I can’t imagine how smooth that must have felt to the local populace at the time.
In 1902 the first apartment complex created mostly from reinforced concrete was built in Paris, wheras two years later the first high-rise building was built in America.
Not a building method, but a vastly great technologicall improvement happened in 1913, A company in America decided to mass produce and mix the concrete, delivering ready-mixed loads. This meant that it didn’t have to be mixed on site.
An aesthetic advancement was made in 1915 where the ability to colour concrete was invented, allowing users to step away from what many believe is a droll grey finish.
1936 saw the building of the Hoover Dam which still is regarded as one of the great Concrete feats in history.
While concrete technology seems to always improve, the formula still hasn’t varied much from the same original Portland Formula. These days, new technologies look at more aesthetic ways the concrete can be presented once the final product is produced. Polished concrete, while very popular today, was only invented in 1999 and builders use a number of ways to produce different textures and finishers to their work.
In 2016, a complete building was made using a 3D printer and concrete as it’s source material. Obviously this is not the small 3D printers you and I know of but a marvellous achievement and an indication of what might be possible into the future.
The Future?
I don’t think many people can guess what will happen with the use of concrete in the future. It’s availability and price combined with its benefits, it’s strength and malleability, and it’s ease of use mean that it will likely be available and the preferred building method for a long time.
Either way, we hope you have enjoyed reading a quick history of the history of concrete and can appreciate what man kind and civilization have gone through to get where we are today. As concreters, this is a question we sometimes get asked and we hope now that you will be able to even impress your local concreting contractor with all your new knowledge.
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