SINCE THE Romans began doing it with great panache more than 2,000 years ago, road-building has been something of a sweaty and grubby business, involving heaving great quantities of rocks and stones into place and, in more recent times, covering the surface with asphalt or concrete. Now a group of Swiss researchers think they have come up with a more elegant solution. Strange as it may seem, this involves knitting.
Martin Arraigada and Saeed Abbasion of the Swiss Federal Laboratories for Materials Science and Technology use a robotic arm to lay out string in a series of elaborate patterns. As the knitting takes shape, layers of stones are added and tamped down. The string entangles the stones, keeping them in place. The result is a structure that is surprisingly stable and strong. In one experiment a section of pavement put together in this way withstood a load of half a tonne. The encapsulated stones hardly moved at all.