Such technology is being developed by scientists at the Swiss Federal Laboratories for Materials Science and Technology (Empa). The specialists are trying to eliminate the use of asphalt and bitumen to reduce environmental damage and meet the demands of a carbon-free economy.
The scientists used gravel as the main material for a road surface with string that held together pillars reaching a height of 80 cm. In pressure testing, they were shown to withstand loads equal to 20 tonnes.
The scientists used the same string that is widely used in Switzerland to wrap waste paper. And to make up for a lack of durability, a robotic arm was deployed to stack layers of gravel and string in a pre-programmed pattern.
Asphalt used in road construction is made up of stones bound together with bituminous binding material. But the scientists reasoned that string could be used instead. This will reduce air pollution and eliminate the use of petroleum products.
Five layers of gravel and string were used in the experiment and a load test revealed that the experimental road material was able to withstand pressures equal to half a tonne. The team’s next goal is to carry out dynamic load testing with rolling pressure as well as studying different patterns and mesh widths and their effects on the stability of the pavement.