Driving on a road littered with potholes can be a bit like trying to navigate an obstacle course. While the obstructions seem like they should be easy to mend, methods to fill the holes are costly, tedious and often only possible to carry out in the summer seasons.
But a group of students in Ohio has proposed a quick fix for the nasty urban problem. The Case Western Reserve University undergraduates have developed a non-Newtonian, silly putty-like fluid that conforms to the confines of potholes but hardens under the pressure of cars and bicycles, allowing for an effective (albeit temporary) solution to the problem.
While Newtonian fluids maintain their liquid state regardless of disturbances, non-Newtonian fluids are much more variable. The viscosity, or resistance, of these substances changes based on the forces or stresses applied to them.
The engineering students specifically chose a shear-thickening substance—when a stress is applied, such as a car’s tire, the substance hardens. The special properties of the material cause it to flow under low pressure but thicken and lock under high pressure.
"The harder you push on it, the higher the viscosity gets,” Michael Graham, a chemical engineer at the University of Wisconsin, Madison, explains to ScienceNOW. “If you push it really rapidly, the particles in the corn starch don't have time to rearrange and get around one another and they jam up.”
The group developed a powdered mixture that’s stored in waterproof bags made out of a strong Kevlar-like fiber. To create a pothole patch, city employees simply add water, seal the bag and place it in the hole. The holes would then be covered with a black adhesive fabric so as not to alarm drivers.
Unlike the current repair method—a lengthy process in which holes are packed with asphalt—the students’ method requires no specialized personnel, expensive equipment or even training. City employees can carry the fluid in the trunks of their cars and drop it in potholes as they become apparent.
The bags can be used for weeks at a time and can even be removed, stored and reused at a later time.
Although they have been tested on a number of potholes in Cleveland and have successfully withstood high amounts of traffic, the materials must still be examined under real-life winter conditions.
The students plan to patent the device and say they are in talks with a number of companies to develop the product further.