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| 3.12.1
The Growing Need for and Importance of Waste Minimization
and Recycling |
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Recycling means reintroducing waste material into
the production process, to supplement primary resources.
The use of waste as a raw material saves resources
and primary raw material, reduces air and water pollution,
and extends limited landfill life. Recycled products
can also save financial resources through lower material
costs and lower disposal costs. In some cases, using
recycled products can improve material performance
as well. Consequently, using recycled materials is
a key aspect of more efficient and environmentally
sensitive highway design and construction. [N]
Recycling also saves energy. A quantitative assessment
of environmental impacts on life cycle of highways
found that most energy is consumed in the manufacturing
stage of construction materials, with consumption
of 1,525 tons of oil equivalent (TOE)/functional unit
(1 km and 4 lanes of highway). [N]
Energy consumption in the maintenance and repair stage
was also fairly high among the life cycle stages;
the next highest consumption was for the construction
and demolition stage. Through the whole life cycle
of 20 years, 2,676 TOE of energy/functional unit was
consumed, and this corresponds to SO2, NOx, and CO2
emissions of 62.1 tons, 17.1 tons, and 2,438.5 T-C,
respectively. [N]
The United States spends approximately $13 billion
annually (1999 dollars) on highway construction and
repairs, requiring nearly 350 million tons of both
natural and manufactured construction materials. [N]
Approximately 4.1 billion metric tons of non-hazardous
solid waste materials are generated annually. The
majority of these materials are being landfilled in
many states; however, landfills and access to materials
are increasingly limited by growing environmental
regulations and permitting requirements, restrictive
zoning laws, land uses, and other economic considerations.
Community opposition has restricted the expansion
of and forced the closure of existing landfills, quarries,
and gravel pit operations. The latter has created
localized shortages of construction aggregates and
borrow materials in some areas, further adding incentive
to explore alternatives in order to alleviate such
shortages and to conserve natural resources.
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| 3.12.2
Common Recycling Applications in the U.S. and Europe |
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Research into new and innovative uses of waste
materials is continually advancing. Many highway agencies
and private organizations have completed or are in
the process of completing studies and projects concerning
the feasibility, environmental suitability, and performance
of using recycled products in highway construction.
Reduction of waste material at its source and reuse
of construction waste complement recycling efforts.
Recycled materials are typically used in such applications
as bituminous pavements, Portland cement concrete (PCC)
pavements, road base, embankments and fills, flowable
fills, landscaping, bicycle paths, parking lots, and
appurtenances such as signs, fencing, barriers, traffic
delineators, etc. Some of the most notable uses of
recycled materials in the highway environment over
the last 20 years have included recycled asphalt pavement
(RAP), reclaimed concrete pavement, coal fly ash and
blast furnace slag. A few states and local governments
have passed legislation to promote recycling in road
construction. In some case beneficial use determination
processes (BUDs) evaluate uses though a wide range
of approaches are used; California, Illinois, Massachusetts,
New Jersey and Pennsylvania are working to standardize
the BUD process and create reciprocity. State DOTs
and state environmental protection agencies (State
EPAs) are also trying to balance the desire for increased
use of recycled materials with concerns about potential
environmental impacts of leaching from recycled materials.
FHWA produced a review of the use of recycled
materials in highway construction in the early 90s,
a summary of which is included below. [N]
NCHRP Synthesis of Highway Practice 199, Recycling
and Use of Waste Materials and By-Products in Highway
Construction. [N]
developed a methodology for assessing the suitability
and practicability of specific waste resource materials
in transportation applications, determining appropriate
uses, developing design and construction guidelines,
and evaluating long-term in-service performance and
applied the methodology to a spectrum of waste resource
materials. The project developed a comprehensive CD-database
including material and engineering properties; environmental
information; legislative, regulatory, and litigation
information; history of past use and performance;
references to existing specifications and guidelines;
information on material generation (source, quantity,
existing inventory); and information on ongoing research
and demonstration projects. [N]
Congress has supported development of a Recycled
Materials Resource Center (RMRC) at the University
of New Hampshire to perform research and outreach to
reduce barriers to recycling in a highway environment.
FHWA and RMRC produced a 2001 manual to provide guidance
to assist transportation agencies in the maintenance
of high-quality roads that perform to high engineering
standards over their design life, without future problems,
and to promote cooperative efforts with environmental
agencies to ensure that present and future environmental
problems do not arise when recycled materials are used
in highway infrastructure. Read the Framework
for Evaluating Use of Recycled Materials in the Highway
Environment online. [N] . The
private sector is also developing innovations in processing
and applications.
In 1999, FHWA, AASHTO, and NCHRP sponsored an international
scan tour to Denmark, Sweden, Germany, the Netherlands,
and France to review and document innovative policies,
programs and techniques in Europe and make recommendations
that would lead to the reduction of barriers to recycled
material use. In particular the scanning team sought
applications in highway construction in the ROW (e.g.,
roads, shoulders, medians, bridges, culverts, swales,
appurtenances) though activities associated with highway
construction can also result in use of recycled materials
outside the highway ROW. In Europe, government policies
and regulations such as bans on landfilling, landfill
taxes, and natural aggregate taxes support recycling.
Generally, clear and unambiguous engineering and environmental
test methods and performance standards help to reduce
uncertainty and allow recycled materials to compete
with natural materials. Where tests and standards do
not exist, governments often support recycling by sharing
risk.
In the U.S. there are widespread needs for clear
engineering and environmental test methods and performance
standards. The owner or contractor generally assumes
risk. The States, academia and the private sector are
conducting significant research. In the U.S. some recycled
materials like RAP, coal fly ash and blast furnace
slag are widely used in a true free market situation
because of their excellent performance and competitive
costs. Other materials are used more locally in response
to more specific local market forces. There is little
federal government involvement, except for construction
procurement guidelines for materials like coal fly
ash. Rather, the situation is driven at the state level.
For example, the State of Pennsylvania has adopted
legislation to promote recycling in the highway environment.
RMRC's Report
for the International Scan Tour on Recycling Techniques,
is available on-line. [N]
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| 3.12.3
General Recommendations for DOTs with Regard to Recycling
and Waste Management |
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The International Scan Tour Report generated a number
of recommendations for AASHTO's Standing Committee
on the Environment and Subcommittee on Materials that
are pertinent to recommended practices for state DOTs:
[N]
- Include a recycling strategy in the sustainability
aspect of strategic plans and long range research
priorities.
- Create a framework to consider the use of recycled
materials in project planning, alternatives analysis,
and mitigation analysis.
- Encourage long term materials supply plans and
recycled materials availability plans.
- Develop clear engineering and environmental guidelines
at the State and Federal level that are available
for suppliers and decision-makers.
- Develop courses on recycling.
- Evaluate contractors with respect to use of recycled
materials or environmental protection during contract
performance reviews.
- Develop and implement the use of warranty and
performance based specifications. [N]
The following practices are also recommended to
facilitate environmental stewardship in materials
management: [N]
Materials should be used in the most effective way
possible.
- Structures should have long lives.
- Materials should be recyclable.
- Consumption of energy in the construction development
should be optimized.
- Alternatives for conventional resources should
be considered.
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| 3.12.4
Life Cycle Cost-Benefit Analysis |
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The most recent TRB research needs meeting called
for an expansion of life cycle analysis to reduce
waste, prevent pollution, and encourage recycling.
[N]
FHWA's Highway Economic Requirements System (HERS)
is an example of a tool that supports tradeoffs between
preservation and improvement projects. The HERS application
is based on the Highway Performance Monitoring System
(HPMS) database, and is intended to replace HPMS as
the source of biennial federal needs studies submitted
to Congress. The HERS algorithms address both highway
capacity and pavement preservation needs. Thus, state
application of HERS or HERS/ST are uniquely suited
to asset management studies that are more comprehensive
than those addressed by individual management systems
(e.g., pavement management and congestion management)
and can explore tradeoffs between system preservation
and system improvement or expansion.
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| 3.12.5
Areas for Recycling Applications |
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Areas for recycling applications in maintenance,
many of which are applicable for other parts of the
organization, are described in detail in Section 10.13.
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| 3.12.6
Specifications for Recycled Materials in Transportation
Applications |
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Available AASHTO or DOT specifications for the recycled
materials covered in ensuing sections are included
as web links within those sections, and more specifications
are being developed all the time. The Recycled Materials
Resource Center (RMRC) has a project underway to Develop
and Prepare Specifications for Recycled Materials
in Transportation Applications. Participants in the
project―Caltrans, FDOT, Illinois DOT, Mass Highway,
Michigan DOT, Mn/DOT, NHDOT, NJDOT, NYSDOT, NCDOT,
Ohio DOT, PennDOT, TxDOT, and WisDOT― identified
the recycled materials of greatest interest to DOTs
and assisted in the development of specifications.
Six material/application combinations are underway.
The first of these, a specification for glass cullet
use as an aggregate base course, was published in
2001 (M-318-01). This past year, a second specification, "M-319-02,
Reclaimed Concrete Aggregate for Unbound Soil-Aggregate
Base Course," was published in the 22nd edition
of the AASHTO's Standard Specifications for Transportation
Materials and Methods of Sampling and Testing.
A third specification, "Use of Recycled Concrete
as an Aggregate Substitute in PCC Pavements," is
under review by the AASHTO Technical Section. A specification
for coal fly ash in embankments has been tabled by
the Technical Section, while a draft specification
for reclaimed asphalt pavement as an aggregate in
asphalt concrete has been prepared for submission
to the Technical Section. The last specification on
the use of roofing shingle scrap as an aggregate for
asphalt concrete is in preparation.
See also:
As of February, 2004, specifications under development
via RMRC projects include the projects listed in the
Appendix. RMRC keeps an updated list at their RMRC
Resources and Specifications site. [N]
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to Section 3.13 » |
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View
Table 11: FHWA Summary of Known Uses in Waste Applications 