Using Recycled Industrial
Materials in Roadways
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I
Greening the Nation's Infrastructure. THIS
fact sheet discusses the use of industrial materials in roadways and other
infrastructure projects as an alternative to virgin materials and construction
I \ \ products. Industrial materials are the byproducts of industrial processes.
Each year in the United States, industries produce over half a billion tons
of potentially usable materials, such as coal combustion products (CCPs),
construction and demolition (C&D) materials, spent foundry sands, used
tires, and slags. Many have chemical and physical properties that make them
valuable resources when recycled or beneficially reused, but they are often
disposed of as waste. The U.S. Environmental Protection Agency (EPA) is
committed to increasing the recycling of industrial materials as part of its
Resource Conservation Challenge, a national effort to save energy and reduce
greenhouse gas emissions by managing materials more efficiently. Industrial
materials recycling is helping to green the nation's infrastructure by making
roadways more durable, conserving natural resources, decreasing energy use,
and reducing greenhouse gas emissions.
www.epa.gov/industrialmaterials
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Why Use Industrial
Materials in Roadways?
Environmental Benefits
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Since many industrial materials are used to replace non-
renewable virgin materials that must be mined and processed,
using industrial materials conserves natural resources and
reduces the energy use and pollution associated with these
activities. For example, substituting fly ash (a CCPI for portland
cement in concrete saves the energy and greenhouse gas
emissions associated with producing cement. Roads and other
structures made with industrial materials can be more durable.
Maintaining and replacing roads less frequently is good for the
environment because it conserves natural resources and energy.
Economic Benefits
Using industrial materials makes good economic sense for
project owners and contractors. If industrial material use is
planned from the beginning, the total project bid cost can be
lower, allowing the project owner to accomplish more work
with the same budget. Industrial materials are often less
expensive than the virgin materials they replace, and recycling
or reusing materials onsite can reduce material hauling and
disposal costs. Putting industrial materials such as fly ash to
use in infrastructure projects also reduces the need for new
or expanded landfills, saving valuable landfill capacity.
Performance Benefits
Industrial materials offer significant performance enhancement
benefits. For example, steel slag, when used as an aggregate
for asphalt roadway riding surfaces, has a high-friction surface
that makes driving safer. Using fly ash as a partial replacement
for portland cement in concrete enhances the durability and
smoothness of the concrete. Rubber tires used as lightweight
fill material offer outstanding long-term performance benefits
and are less expensive than many alternatives. Asphalt
pavement made with used tires is also more flexible, quieter,
and less prone to cracking than standard asphalt pavement.
Green Design
Organizations are encouraging highway construction and
renovation activities that have a reduced impact on the
environment. The U.S. EPA, the Federal Highway Administration,
and the Maryland State Highway Administration sponsor the
Mid-Atlantic Green Highways Partnership (GHP). The GHP seeks
to incorporate environmental streamlining and stewardship
into all aspects of the highway development lifecycle, including
using industrial materials. Visit www.greenhighways.org
An Overview:
Roadway Applications for
Industrial Materials
Roadways are a central component of the nation's
infrastructure and present a wide array of opportunities for
using industrial materials. This diagram illustrates the most
common roadway applications for industrial materials. Note
that the availability of specific industrial materials can vary
regionally, so visit the Web sites in the "Resources for More
Information" section of this document for information on
identifying suppliers of industrial materials in your region as
well as local C&D materials recyclers.
Recycling Industrial Materials in Concrete Pavements.
This image portrays the use of industrial materials in hot-mix asphalt
pavement (HMA), however, industrial materials have very similar
applications in traditional portland cement concrete
pavement (PCC). Both HMA and PCC pavements
require aggregates, and the list of aggregates
under the "Concrete Retaining Wall" and
"Asphalt Base" applications can be used
in both HMA and PCC roads. PCC roads
can incorporate ground granulated blast
furnace slag and reclaimed concrete
aggregate (BCA) more easily and in
larger volumes than HMA can. See the
American Association of State Highway
and Transportation Officials (AASHTO)
provisional standard MP 16-07 for use of
BCA in hydraulic cement concrete.
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©
Embankment
Topsoil on roadside embankments can be
amended with compost, pulp and paper
byproducts, FGD material, or steel slag, if soil
conditions merit. These industrial materials can
improve the condition of the soil, increase plant
growth, and reduce runoff. Foundry sand, steel
slag, and coal ash are suitable for embankment fill.
(?) Mechanically Stablizied Earth (MSE) Wall
Retaining walls hold back soil and rock and
prevent the erosion of roadside slopes, they are
often made of concrete or modular blocks.
Fly ash and ground granulated blast furnace
slag can be used as partial replacements for
Portland cement in concrete, making the
concrete stronger and more durable.
Concrete aggregates can include bottom ash,
foundry sands, reclaimed concrete, and blast
furnace slag.
Portland cement can contain fly ash, FGD
gypsum, foundry sands, drywall, blast furnace
slag, and steel slag.
Asphalt Surface
Blast furnace slag, steel slag, and boiler slag
can replace virgin aggregate in the asphalt
surface layer.
Always consult your state and
local environmental agencies
to determine approved uses of
industrial materials.
(T) Asphalt Base
Fly ash, bottom ash, foundry sands, and reclaimed
concrete and asphalt can be used as aggregate in
the asphalt base layer.
Ground rubber tires and ground roofing shingles
can be added to the hot asphalt surface and
base mix, increasing the flexibility and durability
of the pavement and reducing the need for costly
virgin asphalt.
ClL/Cll) Granular Base and Sub-Base
A variety of industrial materials can be used as
granular base and sub-base, including:
Bottom ash
Foundry sand
Beclaimed concrete and asphalt
Glass
Boofing shingles
Blastfurnace slag
Steel slag
Scrap tires
Fly ash can also be used as mineral filler in asphalt
base, granular base, and sub-base.
Subgrade (Original Soil)
Fly ash can be used to improve the structure and
stability of the subgrade upon which the road will
be built.
Structural Fill
Structural fill supports and relieves pressure from
retaining walls.
« Shredded scrap tires are particularly well suited
for fill applications, they are lightweight, drain
well, and resist frost penetration.
Fly ash, reclaimed asphalt pavement, concrete,
crushed glass, and foundry sand can also be
used as backfill for retaining walls.
Vegetated Swale
One environmentally-friendly way to provide
adequate drainage for roadways is through
vegetated swales, which can help improve water
quality.
Scrap tires, reclaimed concrete or asphalt,
glass cullet, and blast furnace slag can be used
in place of traditional drainage materials, such
as virgin sand or gravel.
The Center for Environmental
Excellence by AASHTO
The Center for Environmental Excellence
(GEE) by the American Association of
State Highway and Transportation
Officials (AASHTO) is a one-stop
resource for transportation officials
seeking environmental information.
The comprehensive Web site includes
tools, information, and case studies on
recycling and waste management.
See: http://environment.transportation.org
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Case Stud
San Francisco Bay Bridge
Reconstruction Maximizes the
Use of Fly Ash in Concrete Mix
Ongoing construction of the new east span of the San Francisco Oakland Bay
Bridge is taking advantage of the unique properties of fly ash and ground
granulated blast furnace slag to enhance the durability and strength of the
concrete used. The California Department of Transportation (Caltrans) started
the new span in 2002 to replace the old, seismically vulnerable span that was
damaged in a 1989 earthquake and subsequently repaired. The chemical and
physical properties of fly ash concrete help mitigate the corrosive effects of
seawater and salt fog and the structural requirements of an earthquake zone.
The high-salt zones of the bridge will use a concrete mix containing 50% fly
ash, which prevents cracking as the cement hardens, a common problem in
a salt-water environment. The round fly ash particles also improve flow and
workability in the mix. The fly ash concrete used is also denser and stronger
than traditional concrete and can better carry heavy loads. Caltrans will use
over 30 concrete mix designs in the new bridge, some containing more than
50% fly ash. In addition, ground granulated blast furnace slag was used in
pier columns to improve durability and workability and reduce bleeding. In
2006, Caltrans received an award for Innovation from EPA's Coal Combustion
Products Partnership (C2P2), in part based on its work on the new Bay Bridge.
Did You Know?
The American Association of State
Highway Transportation Officials
(AASHTO) has developed standards
for using recycled industrial materials
in cement and concrete. AASHTO M
295 and AASHTO M 302 are standard
specifications for using fly ash and
ground granulated blast furnace slag
in cement and concrete in roadways.
Contact your state or local environmental
agency for more information about
approved uses of industrial materials in
your region. You can also contact your
state Department of Transportation to
determine whether they have developed
specifications for using industrial materials
in roadways. See the AASHTO Web site
at: bookstore.transportation.org See
also the American Society for Testing
Materials at: www.astm.org.
WHAT CAN YOU
SAVE TODAY
4L>
RESOURCE CONSERVATION
CHALLENGE
Environmental
Protection Agency
EPA-530-F-08-024
www.epa.gov
July 2009
Resources for More Information
EPA's Industrial Materials Recycling Homepage:
Provides an overview of industrial materials, their
benefits, and opportunities for reuse and recycling:
www.epa.gov/industrialmaterials
EPA's Comprehensive Procurement Guidelines:
Includes information about construction and
transportation products containing recycled
content: www.epa.gov/cpg
Construction Industry Compliance
Assistance (CICA) Center: Contains a C&D
materials State Besource Locator, where you can
find state environmental agency Web sites:
www.cicacenter.org
The Federal Highway Administration (FHWAj
Office of Pavement Technology's Recycling
Web page: Provides information about current
projects and activities, research and references,
publications, and policies pertaining to the use
of recycled materials: www.fhwa.dot.gov/
pavement/recycling
The Recycled Materials Resource Center
(RMRC): The BMBC's mission includes
systematically testing, evaluating, developing
appropriate guidelines for and demonstrating
environmentally acceptable increased use
of recycled materials in transportation
infrastructure construction and maintenance.
This Web site provides information on
recycling and reusing industrial materials in
roadways: www.recycledmaterials.org
User Guidelines for Byproducts and Secondary
Materials Use in Pavement Construction:
Provides information and general guidance
on engineering evaluation requirements,
environmental issues, and economic considerations
for determining the suitability of using recycled
materials in highway applications: www.
recycledmaterials.org/tools/uguidelines/index.asp
Industrial Resources Council (IRC): Contains
information about industrial materials and their
applications. The IBC is composed of industry
trade associations representing coal combustion
products, foundry sands, iron and steel slag,
wood and pulp materials, rubber materials,
and construction and demolition materials:
www.industrialresourcescouncil.org
Mid-Atlantic Green Highway Partnership:
Seeks to incorporate environmental
sustainability into all surface-transportation
infrastructure, including using industrial materials:
www.greenhighways.org
) Recycled/Recyclable Printed on paper that contains at least 50% post consumer fiber.
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