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| CromaConcept/Pixabay |
When we look around the modern built environment, we see steel, glass, ceramics and whatnot but under all the visible glitter of construction, a wonder mixture ensures stability, durability and even the very existence of structures - concrete. Often dismissed as boring, ugly and inert, the grey sludge oozing out of mixers is actually a surprising, dynamic and incredibly complex mixture, and we need to talk about it more often, feels Ed Conway.
A building material made from a mixture of cement, broken stone or gravel, sand, and water, which can be spread or poured into moulds where it transforms into a mass resembling stone on hardening.
Even now, scientists don't fully understand what's going on inside concrete when it's setting. In chemistry labs this remains hotly-debated territory. Also surprisingly, it keeps on curing (concrete takes 28 days of curing to reach full strength) long after it's apparently set.
Many great dams around the world are still curing nearly a century after being built.
We are not the first folks to be building mega structures with concrete. The Romans had their own form of concrete and there's enough evidence to suggest that our ancestors used a form of cement 10,000 yrs ago.
After the Roman Empire bit the dust, the recipe for concrete was forgotten. Come 15th century, an old manuscript by Vitruvius reappeared with hints of this building recipe, fuelling a race to "re-invent" concrete anew.
A hell of a lot of it. Each minute, construction blokes around the world pour out the equivalent of more than 200,000 bathtubs of concrete and thus, every year we use enough concrete to cover the entire landmass of England.
Alarmingly, cement, the soul of concrete is responsible for roughly 7% of all global emissions, which is more than aviation and deforestation combined.
To reduce carbon footprint, there's a growing focus on cement tech these days, as it happens to be one of the trickiest obstacles on the path to getting carbon emissions down to net zero by the year 2050.