for plastic lumber remains high
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
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 2x2 up to 12x12 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.”