Biomimetic materials: re-thinking how we build stuff

Published at: 13 June 2016

Spider-silk towers? 100-storey wooden skyscrapers? Eggshell toilets? Nature is changing how we build and sometimes it can all seem a little sci-fi

Looking at the upwardly growing skyline of the world’s major cities, it’s easy to identify the two materials best-loved by civil engineers: steel and concrete. Since the dawn of the Industrial Revolution, large amounts of energy have been expended on these two materials, and they represent a far greater burden on our total carbon footprint than most people realise. In addition to being energy-intensive, steel and concrete are heavy.

If we consider instead the building blocks of the natural world, we see materials that are lightweight and that are produced with relatively low energy input under ambient temperature and pressure conditions. The building blocks of nature are completely recyclable, and a relatively small number of building blocks can be put together in a wide variety of ways to make materials for very different functions Dr Michelle Oyen explores these building blocks and look at examples in nature of how we might rethink how we build our future cities.

“As engineers,” Oyen says, “we throw energy at problems to make things technologically better, but we don’t necessarily think about the consequences of what all of that energy input is doing.” The concrete industry, for example, produces 5% of global CO2 emissions. The beauty of the materials that Oyen and colleagues are developing is that they can be produced in gentle, low-energy conditions.

“For the last 10 years we’ve been trying to figure these things out. We’ve probably still a few more years to go and then maybe the following decade will be taking all the things we’ve learned and being able to apply them to making new materials.” One such solution is a little more gory: bricks built from sand and blood.

"Animal blood is one of the most prolific waste materials in the world," says Jack Munro of his award-winning proposal, a 2012 graduate of University of Westminster in London. "The blood drained from animal carcasses is generally thrown away or incinerated despite being a potentially useful product."

A single cow, Munro argues in his report, can produce about eight gallons of blood after it’s been slaughtered. Munro collected blood from four cows for his early tests, adding an antibacterial agent to stave off fungal growth and mixing it with sand. Then, he poured the mixture into a simple formwork and baked it at a fairly low temperature—only 160 degrees. He found that after only an hour of baking, the blood proteins coagulate to form a strong insoluble mass, bonding with the sand. He experimented with making glue first, then moved on to bricks.

Some of the world’s leading architectural institutions, like the University of Cambridge’s architecture department, are currently working on genetically modifying plants to make super-wood for building. “We’re looking at what’s in plants that give rise to properties that are beneficial for building bigger buildings: strength, resistance to rot, durability,” says senior lecturer, Michal Ramage.

It won’t be long before we have spider-silk towers or 100-storey wooden skyscrapers. The options are as diverse as the boundless multiplicity of nature and we’ve only scratched the surface. In the words of that great intellectual William Wordsworth “Come forth into the light of things, let Nature be your teacher.”

Read the full story here.

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