Surprising facts about concrete

Modern house

Concrete is the material that will continually surprise and amaze you. You might think of it as the stuff that makes pillars to hold up raised highways (and it is, of course) but it’s also used in such ornate ways that you can find luxurious concrete basins in Australia, as well as bathtubs, tables, seating and much more.

Here are some surprising things about concrete that you might not have known before.

Fact 1: when reinforced, it resists both fire and water

The elements of fire and water may come as opposites, but reinforced concrete is built to withstand them all. It’s virtually impervious to fire, neither succumbing to being set on fire, nor releasing any toxic fumes when it comes into contact with the extreme heat of fire. When you’ve seen the main structure of buildings still standing even when everything else within has been burnt out, that’s thanks to the concrete.

Equally, it possesses natural resistance to water that is then enhanced with special mixes and the uses of sealant. That means it can be used below ground in damp conditions just as well as it can for grand overground structures.

Fact 2: it has been in use since ancient times

The exact makeup of concrete hasn’t been the same over its entire history, but the material has been used as an essential element of construction since ancient Rome. The Romans used a mixture of volcanic ash, lime, and water, which together they named “pozzolana.” There are writings discovered from Roman engineers such as Vitruvius which outline the production of four distinct types distinguished by colour: grey, red, white, black.

The fact that concrete has endured as a go-to material through the ages just demonstrates how fundamentally fantastic it is. Where we have departed from some materials and methods completely as time marches on, concrete remains a stalwart ally.

Fact 3: It was used as a precursor to radar

As radar was still being perfected and applied in the United Kingdom during the early days of World War 2, the key instrument in detecting incoming aircraft on the southern coast of England were huge parabolic acoustic mirrors made from concrete. These were known colloquially as “listening ears” and were dotted along the coastline as an early warning system. As part of the early radar family, concrete was therefore a component in decisive technology that helped to defeat the axis powers.

Fact 4: concrete and cement are different things

Some people wrongly believe that the terms concrete and cement are essentially interchangeable terms. In fact, cement is a constituent ingredient of a mixture that is known as concrete. Therefore, concrete is the broader term, referring to a mixture of about 65 percent aggregates, 20 percent water, and then 15 percent cement. The cement acts as a hardening agent when the material is placed, which then binds together the aggregates and other ingredients.

So, if you ever hear people calling the pavement cement, for instance, know that it is in fact only part cement, and the correct name for the material is concrete.

Fact 5: you’ll find the world’s largest concrete structure in China

At the time of writing, the world’s largest structure made from concrete is the Three Gorges Dam in China’s Hubei Province. The dam straddles the mighty Yangtze River, and while it was finally constructed between 1994 and 2006, the history of the dam goes back to the pre-war period where the Nationalist government under Chiang Kai Shek began exploring the possibility of building a dam in the area to help prevent flooding.

The dam now can generate up to 22,500 MW of electricity, and the main reservoir holds the same amount of water as Lake Superior.