A Toronto-based technology transfer company has licensed its process for mixing waste plastics and tires in road paving asphalt, and is pursuing projects to boost the use of waste materials in paving. Polyphalt Inc. has licensed Polymer Asphalt Products of St. Louis to use its process in paving projects in Missouri, Illinois, Iowa, Nebraska, Arkansas, Indiana, Kansas, Tennessee and Kentucky.
John Mead, project development manager, said Polyphalt expects the market to grow for modified asphalt in the next few years as new specifications are introduced.
Mead said his company had spent 15 years researching ways to stabilize polyethylene and rubber tire scrap in asphalt. The breakthrough came in 1991, when scientists at the University of Toronto developed a workable additive combination.
``The problem with much plastic waste materials was that they tended to work their way to the top surface, especially in the summer months when the asphalt got hot. We found a way to stabilize the plastic with chemical additives and patented it,'' Mead said.
He acknowledges the polymer asphalt product costs more than unmodified asphalt, but said it is more flexible, less likely to form ruts or crack and has a higher tolerance for cold weather.
The company has used the material in projects in California, Australia and Ontario. Mead esti-mated that most blends of material used in road paving applications would result in about 6 percent of the pavement by volume being plastic.
Polymer Asphalt Products is associated with Lionmark Construction Co. of St. Louis, a leading asphalt and cement supplier in the Midwest. The company recently completed a blending facility and asphalt terminal on the Mississippi River in St. Louis, where the Polyphalt blends will be made.
In the meantime, a Paris-based company, Alloyed Blend Polymers, has used its Starflex-brand modified asphalt to pave roads near the Oneida Nation Museum in Oneida, Wis.
Like the Polyphalt material, the French asphalt uses primarily low density PE to modify asphalt and make it more flexible while making it more temperature- and wear-resistant.
Oneida Tribal managers say if the use of the material is successful, they could build a plastic bag recycling plant to supply a blending plant for Starflex.
