In 1979, Minnesota began mixing ground-up scrap tires into two asphalt test roads; years later, FHWA said both experimental sections were still performing well

Each year, millions of tires reach the end of their usable life. Once they can no longer be safely used on vehicles, they become difficult to dispose of properly. But what if one could use some of that rubber in building roads? This is something that was attempted in Minnesota many years ago, when they added crumbled tire rubber into asphalt to see if it would help with winter road performance. It was an interesting way of giving tires a new lease on life under cars’ wheels.

The state's Department of Transportation put to the test two sections of asphalt made using a procedure called PlusRide. Years after the Minnesota experiment began in 1979, the Federal Highway Administration (FHWA) reviewed the PlusRide sections and found that the pavement had performed well structurally, although it did not provide the expected de-icing benefits. However, the pavement did not provide the expected ice-removal advantages that researchers hoped to achieve through the use of recycled rubber. This case is, thus, a good example to learn about road engineering because a recycled product can be used in a pavement but still not make it economically beneficial.