November 21, 2012

Recycled plastic mixed with asphalt

BRADLEY FEHR

Vancouver city construction crews (above) lay down the asphalt made with recycled plastic on Kingsway.

BRADLEY FEHR

editor

The City of Vancouver is conducting trials of a warm mix asphalt that includes a wax made from recycled plastic bottles.

“It’s a way to use the plastics that are out of the blue bin,” said Peter Judd, the city’s general manager of engineering services.

City construction crews are paving a four-block portion of Kingsway using the new mix during the trial.

The wax makes up about one per cent of the asphalt by weight.

“When you put it in, it makes the asphalt more fluid and workable,” Judd explained.

This is the first field test on a busy thoroughfare, after the product went through rigorous lab testing starting July and subsequent paving of short sections of roads.

Judd said no difference has been found in its performance of this new mix compared to regular asphalt.

A Toronto-based company, GreenMantra, has developed a process to recycle plastic into wax, which is then added to the asphalt mixture.

About 400 kilograms of the wax will be used in the four-block strip.

The use of warm mix asphalt is growing throughout North America.

It requires less energy to make and produces less odour.

The city has been experimenting with different mixes since 2008.

“It doesn’t take as much fuel to mix it up,” said Jack Davidson, president of the B.C. Road Builders and Heavy Construction Association.

“That’s where we want to go as an industry.”

His association represents firms engaged in all aspects of road building, rehabilitation, heavy construction, highway maintenance and the supply of related goods and services.

The city’s own crews are performing the trials and the B.C. Road Builders and member firms aren’t involved in this project.

“If it (the new asphalt mixture) works, it’s the way to go,” Davidson said.

“We’re trying to get the temperature down as it saves green house gas emissions.”

Typically warm mix asphalt carries about a three per cent premium over hot mix asphalt, however, the city believes this premium will drop as it is used more, fuel prices increase and emission standards are factored in.

There is also the potential for additional grinding and re-using cycles for the pavement, as the wax helps prevent the aging of the asphaltic oils.

“Warm mix isn’t new,” Judd said. “The difference is we’re using recycled plastics.”

The plastics have a lower value than other recycled material, so the city is happy to find a use for the material.

While the wax from the recycled bottles is currently made in Ontario, the city is hoping that local companies will start producing the material.

BRADLEY FEHR

Peter Judd with the city shows off plastics from a blue recycling bin and a bag of wax pellets that is made from them.

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