From building rubble to plastic waste to discarded face masks, scientists are constantly investigating new alternative materials to help reduce the environmental impact of road construction. One of the most recently explored possibilities comes from researchers in Switzerland who are investigating how roads could be reinforced with simple materials and recycled after use.
Carried out by researchers at the Swiss Federal Laboratories for Materials Science, a new study demonstrates how patterns of string, carefully laid by a robot, can be used to bind asphalt together and thus replace environmentally unfriendly bitumen which is extracted from crude oil and generates harmful gases during production and use.
As part of the new study, the scientists laid a rubber mat on the bottom of a test box to simulate the deformable bed beneath the pavement. They then layered stacks of gravel and string on top of one another, with a robotic arm setting out the string in a pre-programmed pattern. Five layers of gravel and thread were formed inside the box for mechanical tests.
To examine its durability, the researchers then performed load tests which demonstrated that the subsurface road, made of gravel and string, was able to withstand the pressure of half a tonne of weight without the stones moving much. The team also used computer modeling to track the movement of the stones and the stretching force of the thread.
The team was careful to note that while the current form of the material isn’t yet ready for use on roads, these early experiments are a good indication of the method’s potential to help build more sustainable roads. Next, the team plans to carry out tests that more closely simulate the real-world conditions of roads, as well as see how different thread patterns perform in test conditions.
“We want to find out how a recyclable pavement could be produced in the future,” says team member Dr. Martin Arraigada. “To do this, we are using digitalized construction methods in road construction for the first time.”
Image source: Swiss Federal Laboratories for Materials Science
