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”.


You thought London was bad? Rents in the commuter belt are soaring, too

Grays, Essex: the best bang for your buck. Image: Getty.

In Harlow, Essex, there are nine flathunters for every spare room going. Demand has risen by 350 per cent over the past two years. Everyone, it seems, wants to live in Harlow. 

This somewhat surprising information – and the dismal image it conjures up of dead-eyed renters wandering the streets, queuing up for viewings – comes from researchers at, who monitored listings and searches on their lettings and flat-share site throughout April to find out where demand is increasing. The answer, it turns out, is in London's commuter towns: savvy renters sick of London's prices and tiny rooms are heading into the Home Counties in search of a better life. 

But their savviness is catching up with them. On average, the rents in the satellite towns monitored by the site (all an hour or less from London by train) increased by 9 per cent over the past two years. Compared to the cool 10 per cent rise in London in a single year, that doesn't sound too bad. But in Benfleet, Essex, average rents increased by 21 per cent in the past year. In six out of the 24 satellite towns surveyed, in fact, rents are increasing faster than in central London. 

Of course, there are drawbacks, that go well beyond the reduction in your proximity to an all-night Tesco Metro. In many of these commuter towns, savings on rent are outweighed by the sheer cost of travelling along commuter train lines, where most ticket prices have far outstripped the rate of inflation over the past 10 years.

In Swindon, for example, an annual season ticket will set you back £8,200. If we're working with average rents, the amount you'd pay for housing plus transport would be £2,840 more a year than you'd need to rent in London and use a zone 1-3 travelcard. The best savings can be found in Grays, Essex, where monthly rents are a mere £440 and an annual travelcard only £2,236. 

As housing and travelling prices rise, it won't be long until even that pied-à-terre in Harlow ceases to be a cheaper alternative. As the site's director, Matt Hutchinson, notes, the trendlines show that the housing crisis is gradually swallowing a large chunk of the south of England: 

What we're seeing is the housing crisis rippling out along the train lines from London. In many cases that means increased competition and rising rents.

At the moment there are still towns and cities offering a good balance between journey time and cheaper rents but, unless we address the need for more affordable homes, particularly in the South East, that won't be the case for long.

You hear that? Let's build more houses, or, failing that, relocate to Manchester.