Future Roads May Be Made by Knitting

A green future may rely on knitting. Automologist MAC reports on this exciting discovery. 

If we want to have a clean green future, we need to not only clean up what drives on roads, but also how we build the roads. A team of Swiss boffins thinks they can help by teaching us how to knit roads…

Have you considered that the basic idea of road building hasn’t changed much since Roman times? Ever since the Romans went on their quest of European dominance over 2000 years ago, the ‘art’ of road building has been a somewhat sweaty, grubby business that employs gangs of men displacing great quantities of rock, stone, sand and aggregate into place. About the only ‘improvement’ has been the use of asphalt as a covering to smooth out the surface and thus protect our delicate derrieres from the rigours they may well have endured if it hadn’t been thought about.

To get the materials, you need to quarry great quantities of rock out of hillsides. You just need to take a short drive north from Kuala Lumpur to Ipoh to see the impact that this is having on the pristine hills of the Titiwangsa Mountain range, where vast roadstone quarries pock the hillsides. Nearer Ipoh, the environmentally important limestone inselbergs are being torn down to make cement, creating vast amounts of carbon dioxide emissions in the process. Of course, asphalt is derived from oil.

So, the Swiss Federal Laboratories for Materials Science and Technology have developed a way to use a robotic arm to weave string into a pattern. As the ‘knitting’ takes shape, stones are added and pressed down. The result is the string and stones becoming entangled and creating a surprisingly strong and stable structure. The team actually built a structure a little like the arches at Stonehenge, with the supporting columns tested successfully to withstand over nine tonnes. Apparently, the ideal material for the string is a mixture that includes recycled textiles and polyester, although they hope to be able to do away with the artificial polyester in the future. The process also is suited to reusing used roadstones.

One of the problems with both cement and asphalt as aggregate is that they are supposed to be impervious and shaped for the water to run off into a drain. The trouble is, water often gets caught in small cracks which it quickly expands, particularly in countries that experience cold conditions, resulting in potholes and of course costly repairs. This new “string theory” allows for the roads to be porous and thus allowing rain to easily permeate, resulting in fewer potholes and a lower impact on the local hydrology.

There is of course a long and winding road to travel before knitting a road becomes a commercial reality. The clever boffins over in Switzerland are still testing patterns and materials and carrying out more tests, and they haven’t tested it out in a real-world scenario yet, i.e. on a road with cars and trucks. However, they do believe that just like when your grandmother used to knit you that Christmas sweater, the end result will depend on starting with a good pattern and using the correct wool.

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