Scientists have designed a “skin” that senses when concrete structures are damaged

Image: Bittbox via Flickr, reproduced under creative commons.

Concrete is pretty great, isn’t it? It’s strong, it’s cheap, it’s easy to use. Let’s hear it for concrete!

On the downside, though, it’s also prone to cracking – if there are swift changes in temperature, for example, or if it’s bearing too much weight. Cracks in concrete structure are annoying at the best of times, but if said structure is holding, say, nuclear waste, they can also be disastrous.

So a team of scientists from North Carolina State University and the University of Eastern Finland have developed plans for a “skin” that would flag up cracks or damage to the concrete’s surface. Their idea involves installing electrodes at the edges of a structure, then applying electrically conductive copper paint across the concrete. The electrodes would emit a constant, low-level current across the surface of the painted “skin”, monitored by a computer. If the surface was weakened, cracked or damaged, the paint would become less conductive, and the computer would sense a change in the signal. You can even analyse the data to produce a map of the damage.

Here’s a cracked piece of concrete, alongside a computer rendering of the damage:

Image: Aku Seppänen.

So far, the researchers have only tried the method out on small, 1m long pieces of concrete, but they’re hoping to test on bigger areas. Dr Mohammad Pour Ghaz, one of the paper’s co-authors, said the team were keen to show the method could work on “real-world structures”.

 
 
 
 

Podcast: Uber & out

Uber no more. Image: Getty.

Oh, capitalism. You had a good run. But then Transport for London decided to ask Uber to take some responsibility for the safety of its passengers, and thus did what 75 years of Soviet Communism failed to do and overthrew the entire economic system of the Western world. Thanks, Sadiq, thanks a lot.

In the unlikely event you've missed the news, the story so far: TfL has ruled that Uber is not a fit and proper company to operate cabs, and revoked its licence. Uber has three weeks to appeal before its cabs need to get off the road.

To commemorate this sad day, I've dragged Stephen Bush back into the podcasting basement, so we can don black arm bands and debate what all this means – for London, for Uber, for the future (if it has one) of capitalism.

May god have mercy on our souls.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason. 

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