Can we recycle concrete?

CrowdScience

BBC

Science

4.8 • 985 Ratings

🗓️ 12 November 2021

⏱️ 27 minutes

🔗️ Recording | iTunes | RSS

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Summary

Concrete is the most widely used substance on earth after water. It’s quite literally the foundation of the modern world, and no wonder - it’s strong, cheap, and mouldable into nearly any shape.

But these benefits come at a cost: concrete production is responsible for around 8% of global CO2 emissions - that’s around three times more than the aviation industry.

Concrete might not look pretty, but given its carbon footprint, should we be more careful about how we use it? And rather than throwing waste into landfill, could we recycle it instead? That’s what Crowdscience listener Catherine wants to know.

To investigate, Marnie Chesterton and Anand Jagatia learn more about what makes concrete such a brilliant and versatile material. It’s down to the chemistry of how cement dries – which, it turns out, is anything but boring. They find out how the stuff is made, and why that produces so much carbon. And they hear about some ingenious projects to repurpose demolition waste – including creating underwater habitats for marine life, and using 3D printers to turn crushed concrete into street furniture.

With Prof John Provis, Prof Becky Lunn, Chris LaPorta, Sheryl Lee, Dr Edward Randviir and David Lacy

Presented by Marnie Chesterton and Anand Jagatia. Produced by Anand Jagatia for BBC World Service

[Image: Discarded Concrete, Credit: Getty Images]

Transcript

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0:00.0	Take some time for yourself with soothing classical music from the mindful mix, the Science of
0:07.0	Happiness Podcast.
0:08.0	For the last 20 years I've dedicated my career to exploring the science of living a happier more meaningful life and I want
0:14.4	to share that science with you.
0:16.1	And just one thing, deep calm with Michael Mosley.
0:19.4	I want to help you tap in to your hidden relaxation response system and open the door to that
0:25.4	calmer place within. Listen on BBC Sounds. You're listening to Crowd Science from the BBC World Service, the show powered by your curiosity and questions.
0:43.0	I'm Marnie Chesterton, and in the background you can probably hear my fellow presenter,
0:48.0	Annan Jagatir, in his kitchen, creating an underrated and miraculous substance from a few simple ingredients.
0:55.0	Concrete. How's it going, Anand?
0:58.0	Okay, I think that's looking pretty good.
1:01.0	Yeah, quite smooth.
1:02.0	Brilliant. So what I want you to do is pour it into the mold that you should have next to you.
1:07.0	Okay, so it's in the mold and I haven't made any mess, don't tell anyone.
1:12.0	What do I do now?
1:14.6	Okay, and now I want you to watch it set.
1:19.8	Make sure you note down any observations. It says setting time is approximately 12 hours.
1:27.3	And we'll be getting live updates from Anand as the situation progresses. But joking aside, although it might sound
1:34.8	incredibly boring, the science of what's happening inside concrete as it dries is
1:40.4	not just fascinating, it's vital to understanding everything from climate change to the homes
1:45.8	we live in. And the reason we're exploring this topic is because of a question from one of our
1:51.0	listeners. Hi Grad Science, I'm Catherine from the UK.
	...

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