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road construction

Plastic bottles filled with soda before being labelled are carried on a conveyor belt at Cott’s bottling plant in Toronto.Fernando Morales/The Globe and Mail

Reams of plastic milk jugs and yogurt containers rinsed out by conscientious consumers could find new life on a highway.

The City of Vancouver on Thursday unveiled a warm-mix paving application that uses recycled plastic – the kind collected in the city's blue box program – to make asphalt.

The North American road building sector has been experimenting with warm-mix systems, which mix paving materials at lower temperatures than conventional hot-mix methods, for about a decade, building on methods developed primarily in Germany.

Vancouver says its method is the first to use recycled plastic, adding another green feature to a technology that can significantly reduce energy use and greenhouse gas emissions.

The city expects its warm-mix system to cut gas use by 20 per cent and to provide the same reduction in carbon dioxide emissions. Currently, the system is 3 per cent more expensive than a hot-mix system, but that premium is expected to shrink or disappear as fuel costs continue to rise.

Pilot projects have shown fuel savings in the range of 10 to 15 per cent and increased lifespans for pavement, says Todd Strynadka, technical services manager with Terus Construction, a road construction group that operates in British Columbia and Yukon.

Warm-mix systems also reduce emissions to which workers are exposed. "Safety-wise for the workers, it's a lot better – and they're finding added benefits in terms of longer life of the pavement as well, because you're not heating the material quite as much," Mr. Strynadka said.

Pilot projects suggest warm-mix asphalt lasts longer, but those results are from projects that are less than a decade old, he added.

"The real test is in 20 years to see how much better it has performed."