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Demand for Plastic Lumber Remains High

July 09, 2010

by Mike Breslin

According to the United States Environmental Protection Agency (EPA), the recycling rate for polyethylene bags and wraps doubled from 2005 to 2008 going up to 832 billion pounds, growing 28 percent since 2005. “This is very strong growth and it even continued in 2008 when the economy was in a global recession. If you look at recycling of other commodities nationwide, EPA reported that recycling overall went down on a volume basis by about 2.7 percent in 2008, but bag and film recycling continued to grow,” said Keith Christman, managing director of plastic markets for the American Chemistry Council.

Although significant progress has been made over the past few years, it is not nearly enough. When asked “paper or plastic?” at the checkout counter, consumers are faced with a range of complex economic-environmental issues, but have voted overwhelmingly for plastic. “About 95 percent of bags used in the United States are plastic. People have decided they prefer plastic bags and stores have largely decided on giving those out,” said Christman.

Recycling waste plastics into plastic lumber has been doing quite well despite a weak economy. “Even though construction is down, we are seeing that plastic lumber is more a preferred material, especially in environments where customers are looking for long life. Contractors, builders and property owners are looking for better value,” said Brian Larsen, president of the Plastic Lumber Trade Association. Larsen is also president of Bedford Technologies, a major manufacturer of plastic lumber products headquartered in Minnesota.

The name Recycled Plastic Lumber (RPL), is deceptive and has come to encompass a continually expanding array of products beyond plastic and composite plastic substitutes for dimensional wood lumber. Today RPL is a catchall term that can refer to material used for construction, outdoor furniture, playground equipment, curbing, speed bumps, railroad ties and commercial-industrial products, to mention a few of the applications.

In less than 20 years, RPL in the United States grew from virtually nothing to what it is now – an innovative and growing industry that mainly relies on recycled consumer plastics for feedstock. The processes were first developed in Europe and Japan in the early 1970s using post-industrial plastic scrap, the only source of low priced polymers at that time.

In the mid 1990s, a small number of American entrepreneurs and engineers formed the Plastic Lumber Trade Association (PLTA) and began to work to improve the woefully inadequate technical standards for plastic lumber that were impeding adoption by architects, engineers and builders.

The U.S. Army Corps of Engineers also became interested in using green building materials in the 1990s. Working with PLTA and Rutgers University, the Corps’ Construction Engineering Research Laboratory embarked on a long-term research and development effort to explore the optimization and use of RPL products. This culminated in the groundbreaking 1997 study Development and Testing of Plastic Lumber Materials for Construction Applications.

The study found that RPL offers advantages over wood, namely resistance to rot and insects, but that the major barriers to wider adoption were lack of understanding of the property differences between wood, the lack of material specifications and design guidance. The Corps submitted its draft test methods, material specifications and usage-design guidance to the American Society of Testing Materials (ASTM).

Prabhat Krishnaswamy, PhD, is a mechanical-structural research engineer. Today he is vice president of the Engineering Mechanical Corporation of Columbus, but in the 90s he was one of the engineers who worked with PLTA to help establish the ASTM standards (D6108 for Manufactured Recycled Plastic Lumber and Shapes; D6109 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and D6662 Specification for Polyolefin-Based Plastic Lumber Decking Boards). “The Army Corps study was one of the first technical evaluations of plastic lumber which eventually led to the ASTM standards. That triggered the growth. The part of the industry that has really taken off in the marketplace is the wood-plastic composite for decking where sawdust is added to polyethylene.”

How much recycled polymer goes into finished goods varies by manufacturer and is unknown proprietary information, but a key selling point are products where a majority of the material is recycled, or even better, 100 percent recycled. This has unique appeal to green-builders, environmentally conscious government agencies and those seeking LEED accreditation (Leadership in Energy and Environmental Design). “I would say it is a fair statement that most manufacturers use a majority of recycled plastics in their products,” said Larsen.

According to Larsen, plastic-composite residential material such as decking costs from 10 to 20 percent more than wood and higher end commercial products two to three times more. “But that added cost is made up in the durability of the product and savings in labor and maintenance, and the cost to go back and replace or reinstall, especially in municipalities.” This is widely apparent in renovated streetscapes and parks across the country where RPL benches, tables and waste receptacles have significantly replaced wood that was pressure treated with chromated copper arsenate or the less toxic alkaline copper quat.

Over the past decade there have been tremendous technological advancements in RPL. Although recycled plastics are used, fillers such as sawdust, colorants and stabilizers are added as well as reinforcing materials such as fiberglass and natural fibers like jute, kenaf and flax. Reinforcing materials provide rigidity and strength and can constitute from 20 to 25 percent of total RPL weight.

Because RPL does not contain toxic chemicals, it is a viable alternative to treated wood, especially in environmentally sensitive wetland areas. There are mechanical property differences between plastic lumber and wood, but with appropriate design considerations, durable, low-maintenance structures can be built. While innovative designs can be competitive on a first-cost basis, RPL structures built from plastic lumber are clear winners on a life-cycle basis.

“It’s more than durability, especially for residential applications. The driving factor is that you don’t have to stain or paint it every few years. Today, if you go to a Home Depot or Lowe’s and pick up composite lumber decking, you are getting a top quality product. All the early generation materials had too much wood flour and other problems, but they have been fixed,” Krishnaswamy noted.

When it comes to brute strength, RPL is making impressive progress. Krishnaswamy was involved in testing a 30-foot arch-truss bridge in Albany, New York constructed of laminated and solid members made from approximately 70,000 recycled milk jugs. Designed to carry highway loading, a fully loaded dump truck weighing almost 32,000 pounds was used to test the bridge. The maximum deflection was only 1.2 inches. The test data is being used to develop further standards for structural RPL designs.

Bedford Technologies manufactures reinforced RPL made of 100 percent recycled high density polyethylene combined with fiberglass, colorants and ultraviolet stabilizers. This combination provides better strength and rigidity for more demanding applications. With over 35 profiles, 15 color options and the ability to manufacture custom shapes and sizes, Bedford claims its products can meet most any need and offer advantages over composite plastic-wood lumber.

Founded in the early 1990s, Bedford has developed a wide variety of commercial-industrial markets. “Our markets associated with manufacturers of outdoor furniture, playground sets, agricultural related equipment and the marine industry are actually going quite well,” Larsen noted.

In fresh water and ocean marine environments, Bedford RPL is used for piers, dock decking and as fendering material in canal locks. “We make a really wide variety of dimensional RPL, from 2×2 up to 12×12 inches,” said Larsen. The larger sizes can be used for piles that can be set in hydraulic cement and are strong enough to be pile driven, or used as cross members.

RPL is ideally suited to marine applications despite costing two to three times as much as treated wood. That is because durability and low maintenance costs are prime considerations, especially for corrosive salt water environments. Equipment and labor costs associated with building and maintaining marine infrastructure are also typically higher than in conventional construction.

“Most of the recycled polymers we use are PE grade with limited recycled PVC. Typically we get our raw material from municipal recycling centers, usually bottle-grade. We buy bales and sometimes ground. We buy in a lot of different forms,” said Larsen.

Even with the growth in recycled plastics over the past several years, in 2008 only 10.9 percent of HDPE (high density polyethylene) and 14 percent of LDPE/LLDPE (low density polyethylene and linear low density polyethylene) was recovered. Obviously, there is tremendous potential for recovery of materials that can go into RPL and a steady demand for durable, low maintenance, green building products. Beside the fact that RPL is heavier than wood, no special training or tools are required to build with it.

“Through the economy downturn there have been some RPL manufacturers that have gone out of business, but that’s true in most industries at this point. There’s been some consolidation. Nevertheless, it’s still a very positive outlook. There are still good markets and good things going on in the industry,” Larsen said.

Alan Robbins, the founding president of PLTA, became a casualty of the late 2008 perfect storm of high commodity prices, a crash in construction and the credit freeze. He was founder and president of The Plastic Lumber Company, which began in 1989 as one of the earliest American extruders of structural RPL for the commercial market. Robbins, one of the early leaders in the industry, contributed to the establishment of the ASTM standards, and developed the markets for the playground, park and recreation industry by designing some of its first products.

Due to defaults by several of his major customers during the economic crisis, Robbins was forced to liquidate Plastic Lumber in June of last year and sell off extrusion equipment. A month later he established Bright Idea Shops LLC as a fabricator of RPL products. “I still have faith in the business. The whole principle of using recycled bottles and making it into product is a very feasible business. I see some nice things going on in the structural arena where these material systems are going for long term durability, good aesthetics and cosmetics looks. I think it’s a great way to go.”