Potholes are an age-old lament, the bane of drivers everywhere. They lead to vehicle damage and add long minutes of desperate headbanging to morning commutes. The traffic and tax burden they cause leave drivers frustrated or angry.
Physicists and engineers at Fermilab have patented a homegrown technology that could increase the lifetime of roads and decrease roadblocks and the billions of dollars currently spent on road repair. The idea involves a new type of asphalt mix, an 18-wheeler and a particle accelerator.
“Accelerator-driven chemistry is a field that is largely untapped,” said Charlie Cooper, general manager at the Illinois Accelerator Research Center at Fermilab. “It’s an advanced manufacturing technique that has hardly been used, and it should allow a lot of things to happen that just haven’t been done.”
Currently roads are made using a hot asphalt mix of aggregate rock and bitumen. Bitumen, a crude oil byproduct, works as a binder to hold gravel together, and it makes up about three percent of the asphalt. This technology hasn’t changed significantly in over 100 years despite its fractures and flaws.
“The asphalt tends to crack,” said Bob Kephart, director of IARC. “Water infiltrates the surface and you get a freeze-thaw. The road breaks up, you get potholes, and this leads to a cycle of repair.”
The method that Cooper and Kephart are developing would work with a new type of asphalt containing a polymer mix that can be cross-linked with an electron beam, which would improve the substance’s material properties. Once the polymer-asphalt mix is applied, a truck carrying a high-power electron accelerator would drive over it, and the electron beam would pass over the surface. This would create stronger roads by increasing the toughness of the material and the range of temperature over which the method works.
Although the initial cost of installing the road would be higher than that of traditional methods — the material is more expensive, and there is the added step of driving over the roads with an electron beam — by improving the lifetime of the roads, the overall cost in the long run may go down.
“If you can increase the lifetime of road by a year, the accelerator, rig and everything is paid off very rapidly,” Cooper said. “There’s a huge amount of money that can be saved based just on the sheer amount of road in the United States.”
Kephart and Cooper have drawn up preliminary designs of both the material and the accelerator. The accelerator, a compact 10-MeV electron accelerator, will employ at least five different new technologies. The team also plans to create a mix that meets the current criteria for roads, taking into consideration qualities such as friction and inertia. They have already found additives that increase the range of temperature over which the road surface can function without cracking when cold or creeping when hot.
Kephart said the idea of using accelerators to treat highways came to him with the realization that they can polymerize materials and can also be mobile. The application extends beyond roadways, with the potential to be used on high school tracks and tennis courts. This particular type of polymerizing accelerator technology could also be used in food, rubber and agriculture, in addition to many other areas.
“Most of technological development associated with accelerators has been driven by the desire to perform scientific measurements,” Kephart said. “Those same accelerators already have a big impact on our economy, our health and much more. I’d like to see the technology we’ve developed here at Fermilab be applied beyond discovery science.”