Highways are in a perpetual process of decay – rain and temperature extremes makes them crack and buckle, and constant traffic inevitably coaxes out axle-jarring potholes.
Back in the 1950s, though, a crack team of American scientists thought they were looking at the end of the era of vulnerable highways. After "extensive tests," according to the below 16mm video "HIGHWAYS OF RUBBER!", they had developed a type of pavement that resisted the pernicious effects of weather and vehicle loads. The secret: a mysterious semi-liquid rubber compound, which they mixed in with other paving materials to create the "necessary resilience to prevent a road from being pounded to pieces."
Have you already guessed that this concept came from the rubber industry? The researchers were in the employ of the U.S. Rubber Company, which in the 1960s became Uniroyal, the maker of "Tiger Paw" tires for muscle cars. Naturally they were enthusiastic about this rubberized pavement, which seemed to hold all the answers to the problems of degradation – the rubber supposedly prevented rain from seeping under the road surface, causing it to break apart, and during extreme heat or frigidness braced it against deformations. It also dried after application in a record time of 20 minutes.
I can find no indication that this miracle product made much headway into the nation's highway system, although it may have been used on an Air Force Base near Miami. But road builders have used the basic idea for several decades, paving roads with rubberized asphalt made from old tires salvaged from the landfill. Arizona, for instance, mixes "crumb rubber" with asphalt and other ingredients to create a pavement has "good performance" as long as 9 years after it's applied, according to a civil-engineering report. Here's what the ground-up crumb-tires look like (most of the steel and non-rubber stuff gets taken out):
(New Mexico State University, Department of Civil Engineering)
Many other states have experimented with rubber-loaded pavement, including California, Arizona, Florida, Washington and Texas. Aside from being a nifty way to recycle tires, the material also is reportedly quieter than normal highway surfaces. So good on you, U.S. Rubber Company lab geeks – you were ahead of your time: