TORONTO — RECYCLED milk bottles are being used to reinforce asphalt in Ontario roads. Not all roads, just an experimental stretch. Plastic roads are not a new idea, but using recycled plastic in roads is.
``The big oil companies already sell a speciality polymer for modifying asphalt,'' notes Anthony Redpath, a chemist at the Ontario Centre for Materials Research. He says the difference between the existing material and the recycled stuff is price.
``Those purpose-made polymers cost $1.50 a pound or more,'' says Mr. Redpath. ``Making it from scrap costs about 20 cents a pound.''
Asphalt made with elastomers - a type of polymer - is used to upgrade gravel roads, giving them a hard surface. There are also roads partially made from recycled tires.
Backing up, why would anybody want a plastic road? Because they don't get ruts in summer or become brittle and chip in the winter. Plastic prevents potholes by tying the asphalt together and making it more flexible in summer and stronger in winter.
Roads take a beating from heavy loads, especially from heavy trucks and buses. A recent study by Metropolitan Toronto Roads Department shows that while heavy vehicles are 7 per cent of traffic volume, they cause 93 per cent of road damage.
``If there were no buses or trucks you wouldn't have road damage,'' says Keith MacInnis, of McAshphalt Industries, a large Canadian paving firm. ``But because this is the real world, we need plastics to reinforce roads.''
Airport runways and taxiways take the full weight of a loaded jumbo jet. While most runways are concrete, plastic is being used on taxiways in Europe.
An experimental section of Highway 401 around Toronto - the busiest highway in Canada - is paved with asphalt reinforced with plastic.
``It has been there for three years,'' says Redpath. ``The official results aren't in but so far the road built with recycled plastic has worn as well as the competition'' reinforced with new polymer plastic.
The road made from recycled plastic is one of many ideas spun from the Ontario Centre for Materials Research. Redpath says his group is also looking for new uses for old tires. One is using tires as a reinforcement for garbage pails or garden furniture made of plastic.
And when they are thrown away, maybe they will come back as a road.