Monday, December 31, 2012

Paving Streets With Recycled Plastic

In Vancouver, they’re using a new kind of material on their roads. Not only is it made partially from recycled material, it also takes a lot less energy to install.
As long as we need roads--and we will, for the foreseeable future, even if we all switch to bikes and electric cars--we might as well find clean and efficient ways to pave them.

Vancouver is experimenting with one way to do that. In a new trial program, the Canadian city is using an asphalt mix that contains a wax derived from plastic trash like milk jugs and shampoo bottles.

The city is using this wax, along with other materials, in what’s called a “warm mix” paving process. When using a warm mix, asphalt can be produced and transported at lower temperatures (about 250° F instead of about 320° F for a traditional “hot mix”). That translates into energy savings and lower emissions at the plants that produce the asphalt and the trucks that deliver it to paving sites. City representatives say it takes 20% less gas to heat warm mix asphalt.

The warm mix process was developed in Europe in the 1990s and has also been adopted in parts of North America. Vancouver has now made this process more efficient by incorporating old plastic trash into the mix.

"We have been trialing warm mix since 2008 with different kinds of additives designed to reduce the viscosity to make placement easier at lower temperatures,” Karyn Magnusson, a city engineer, told Gizmag. “We have now paved three sections of Vancouver roads with this latest trial.”

The recycled plastic wax is made by a Toronto-based company called GreenMantra Technologies. It only comprises about 1% of the mix by weight, but it’s still better to use old plastic in asphalt than letting it sit in the landfill--or swim in the ocean. The recycled plastic also may help prevent the aging of the asphalt, making it easier to reuse. If the recent tests work out, the city hopes to use the recycled plastic mix exclusively in the future.

This is all part of Vancouver’s ambitious plan to be the “greenest” city in the world by 2020. It already made Co.Exist’s list of smartest cities in North America, so it’s well on its way.

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