Much like the exciting world of bioresins, the structural plastic lumber market has made great advancements during the past decade.
But, as in the bioresin industry, economics have prevented structural lumber products from taking hold the way manufacturers hope, even in applications in which the products might be the best-performing option.
Structural lumber's roots, like wood-plastic composites, are in residential deck and railing uses. The structural guys took it a step further, though.
``While the original focus of the industry was on decking, some of us felt that that's well and good, but I'm putting this highly resistant board on top, but have treated-wood framework underneath it,'' said Rich Lampo, a materials engineer with the U.S. Army Corps of Engineers' Engineer Research and Development Center in Champaign, Ill. ``Seems like maybe we're missing the boat here. Why not have an all-plastic structure?''
And so it began.
Picnic tables, trash receptacles, signs, marine pilings, boardwalks, playground equipment and other furniture all have found their way into the mainstream, but still in fairly low volume.
Railroad ties have become a focal point for the industry, though the effort has been hindered by financial problems.
U.S. Plastic Lumber Corp., Polywood Inc. and USPL spin-off Trimax Building Products Inc. all have gone out of business in the past few years. TieTek LLC, the market leader in composite railroad tie industry, opened a second extrusion plant - a 50,000-square-foot facility in Houston in December. But the company has had its own financial misfortune.
TieTek is the only unit of holding firm North American Technologies Group Inc. The company's stock price peaked in the first quarter of 2004 at about $1.20 per share. After a steady stream of disappointing quarters since, shares now are trading around 20 cents.
Despite being made from recycled products, material and engineering costs mean the product costs two or three times more than wood. Even a favorable lifetime cost analysis cannot convince many railroad companies to buy the ties in high volume.
According to a presentation Lampo gave at a composite tie workshop of the American Railway Engineering and Maintenance-of-Way Association, a wooden railroad tie typically costs between $35-$45. Plastic ties range from $75-$125.
``Some people are unwilling or unable to justify the initial cost,'' Lampo said.
Still, composite ties last longer than wood and are cheaper to maintain, and they continue to be a mainstay of the structural lumber industry. Meanwhile, some scientists and engineers have shifted their focus to other applications, such as bridge construction.
In 2003, the world's first all-plastic bridge opened in New Jersey's Wharton State Forest, courtesy of the now-defunct Polywood's innovative technology developed by Piscataway, N.J.-based Rutgers University. The school's Center for Advanced Materials Via Immiscible Polymer Processing is perhaps the epicenter of emerging plastic lumber technology. AMIPP researchers are working to commercialize technology for bone-replacement materials.
Thomas Nosker, principal researcher for AMIPP at Rutgers, said structural lumber manufacturers are spending too much time making simple shapes.
``When you look at steel structures, you see different shapes,'' Nosker said. ``It's not made out of a bunch of rectangles. There are I-beams and T-beams. They are clever about how they fit things together.
``In the beginning, I made a bunch of rectangles. It just wasn't practical. You can't make a lot of money - it's just not structural enough. You can compensate for structure by making a different shape. That's how you start to be able to win the game.''
Nosker said pricing is holding the industry back.
``Let's talk about pricing. A plastic railroad tie weighs about 200 pounds. How much do you have to sell that tie for to make money? That's why the numbers don't work,'' he said. ``Now these bridges are built out of the same stuff, and we can probably get $1-$2 a pound for it,'' Nosker said. ``It's just not smart in my opinion to make too many things shaped like rectangles. It's just not an efficient shape.''
Engineers used extruded plastic I-beams to build a 30-foot arched plastic-lumber bridge near Albany, N.Y., in 2001.
Officials at Worthington, Minn.-based Bedford Technology LLC have been extruding plastic lumber for about 15 years and have been producing structural products for the past five years.
President Brian Larson, also president of the Plastic Lumber Trade Association, said the industry - like so many others working in plastics - continues to work with the architectural community and code officials about establishing specifications for structural plastic lumber. Testing methods are in place, Larson said.
As the industry moves forward, it is only a matter of time before the world takes notice, he said.
``There is a very large market potential out there,'' he said. ``There's a need for it.''