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How 220,000 milk jugs became a bridge made entirely of recycled plastic.
By Tess Taylor
The Metropolis Observed
May 2003
While officials in New York City have been scratching their heads about
what to do with the tons of plastic collected by the municipal recycling
effort--going so far as to eliminate the glass-and-plastic program last
summer--two materials researchers and an entrepreneur in nearby Edison,
New Jersey, have found a least a few neat uses for your discarded bleach
bottles and milk jugs.
Their most recent example? A 30,000-pound bridge. When the tourist season
begins this spring, park rangers and hikers alike will begin crossing the
Mullica River through the Pine Barrens in New Jersey's Wharton State Forest
on a one-lane plank bridge made entirely of plastic.
Rutgers University professors Tom Nosker and Richard Renfree developed the
bridge with McLaren Engineering Group and ex-Fortune 500 accountant
Jim Kerstein. It is the latest in a series of suprisingly efficient
uses they've found for old soda bottles, shampoo bottles, and yogurt containers.
For several years now Kerstein's company, Polywood, has been melting and
molding recovered plastic into boardwalks, railroad ties, marine pilings,
and decking material. But only recently have they developed a mixture hard
enough for load-bearing uses. The secret to their new success: Styrofoam.
In Polywood's Edison warehouse, in a room that smells faintly of burnt kettles,
a few workers mix different grades of shredded plastics with polystyrene
coffee cups, packing peanuts, and take-out containers. A series of machines
heats, cools, and then extrudes the unlikely mixture into two-by-fours,
bench planks, and telephone poles. "We've found that when you heat
these materials up, their polymers wrap around each other and form one extremely
durable fiber," Kerstein says. "We've finally hit on
a very good stiff blend."
"I know plastic might not be exactly intuitive," says Frank Peluso,
a section chief in the New Jersey Department of Environmental Protection's
Office of Recycling and Market Development, which funded the bridge.
"But the material is structurally sound. The bridge can carry up to
thirty-six tons." Peluso says plastic is also an environmentally sensible
choice because lumber used for outdoor functions like bridges, marine pilings,
or park benches typically is treated with arsenic and creosote to prevent
its decay. "The toxic stuff leaches out into its surroundings, and
then the wood rots anyway," Kerstein says. As it ages, wood also releases
carbon dioxide into the environment, whereas plastic lumber does not. "It
actually traps carbon, so we're keeping the air cleaner too," Renfree
says.
Kerstein says that, despite the faint smell, Polywood's manufacturing process
is nontoxic. And the products, which have about a 50-year life span, can
themselves be reprocessed. "We actually just run our scrap through
machines here," Kerstein says, patting a bin of plastic shreds, "so
we don't even make any waste."
Because their durability makes them cost-effective, Polywood's decking,
piling, and boardwalk materials are slowly but surely creeping into parks
and onto railroad tracks across the country. Now Kerstein hopes to find
new markets for the I-beams. "I bet we could make some really cool
stuff with these," he says, kicking one gently. Even plastic skyscrapers?
"The sky's the limit," Kerstein grins.
Kerstein says the key to making a successful recycled product is to think
broadly. "I think in the beginning people thought, Take an old plastic
cup and make a new plastic cup. But that doesn't work. This is really a
better use of the material. It doesn't pollute when we make it, and we can
remake it several times in a row. And it really keeps significant amounts
of materials out of the landfills. I mean, the bridge alone is probably
220,000 milk jugs."
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