Applications and Innovations
Better Roads Staff
‘Re-Made in America’
a Statement of Liberty
From two locations in 2000, Liberty Tire Recycling now operates 33 facilities across North America capable of producing more than 250 million tons of crumb rubber for uses ranging from welcome mats and weightlifting plates to railroad ties and highway asphalt.
What began 11 years ago as a scrap tire collection service to solve a solid-waste problem remains the starting point in a process, says Doug Carlson, vice president of asphalt products for the Pittsburgh-based company.
Liberty has contracts to collect scrap tires from leading big-box tire retailers. The tires are taken to a Liberty facility, where they are run through shredding machines, removing the steel via magnets and the fiber and fluff via vacuum or air-blown systems. “You end up with a pure scrap tire rubber particle that’s about the size of ground coffee,” says Carlson, “and that is packaged and shipped to the contractors, where they can add it to an asphalt product for a mix in accordance with the state’s specs.”
The crumb rubber is shipped in a bulk bag, or “a super sack” as Liberty calls it: “It will vary in weight depending on the size of the rubber that’s in it, anywhere from 1,800 pounds to 2,200 pounds, but generally it’s about a ton.”
What does that translate to on the road? “It depends on the type of mix,” says Carlson. “The rubber content in an asphalt mix can vary from 10 pounds per ton all the way up to 30 pounds per ton of mix, so one super sack can go a long way in production of hot mix.” At one to three tires per ton of hot mix, “that translates anywhere from 800 to 2,000 tires per lane-mile of roadway.”
Company Makes A Flexible Argument
Calling it “The Road to Sustainability,” Liberty Tire Recycling pitches rubberized asphalt by educating on its benefits:
Cracking and rutting resistance: Superior elasticity reduces the occurrence of cracking caused by vertical or horizontal movements beneath the overlay as a result of traffic loads, temperature fluctuations and shifting earth.
Skid resistance: In wet conditions, decreased splash and spray combine with better traction for a safer traveling environment.
Maintenance cost reduction: While in most cases using the same equipment as traditional asphalt application on roadways, longer-lasting properties reduce long-term maintenance costs.
Noise reduction: By upwards of 5 decibels, a quieter traveling surface meets the increasing requirements of public-complaint-conscious agencies.
Here’s A Clean Spec For You
Among the challenges encountered when Ontario’s rural County of Grey started laying rubberized hot-mix asphalt 20 years ago was the picking up of freshly-laid material by the compactors.
Then county transportation and public safety director, Gary Shaw, made an adjustment that today is written into every tender put out for county rubberized pavement work. It reads: Ivory liquid soap must be used with the water solution of the rollers in order to reduce the pickup of asphalt on the roller tires and drums.
No word whether Shaw, having just ended a 45-year career with the County of Grey, is the next Ivory Guy.
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