A growing concern in the development community is for construction that exhibits good environmental stewardship. That is, practices that conserve resources in a manner that allow growth and development to be sustained for the long-term without degrading the environment. Asphalt pavements are economical, efficient and contribute to sustainability in many different ways.
Read the NAPA report: Black and Green: Sustainable Asphalt, Now and Tomorrow (Digital Version)
Read the Joint NAPA/EAPA publication: The Asphalt Paving Industry: A Global Perspective
Read the "Carbon Footprint" analysis by Brian Prowell, Ph.D. in the Iowa Asphalt Report, Green Issue
Read the "Cleaner Water with Asphalt Pavements" report
Take the free Sustainability and Paving Online Training Course, brought to you by Pavia Systems
Some specific environmentally friendly applications of asphalt pavement are discussed in detail below:
Developed by the U.S. Green Building Council, the Leadership in Energy and Environmental Design (LEED) Green Building Rating System™ is the nationally accepted benchmark for the design, construction, and operation of high performance green buildings. LEEDpromotes a whole-building approach to sustainability by recognizing performance in five key areas of human and environmental health: sustainable site development, water savings, energy efficiency, materials selection, and indoor environmental quality. Visit www.usgbc.org for more information on the LEED certification process.
To earn certification a building project must meet certain prerequisites and performance benchmarks ("credits") within each category. Projects are awarded Certified, Silver, Gold, or Platinum certification depending on the number of credits they achieve.
Asphalt pavements contribute to LEED credits in a variety of ways. Asphalt pavements are 100% recyclable. They are used and reused with each cycle of road paving. As such, credits associated with recycling and waste management are attainable. Pervious asphalt mixtures have been used in Ohio for over a generation. Research in the 1970s by the Franklin Institute launched porous (pervious) asphalt pavements, a strategy that both reduces quantity and improves quality of stormwater runoff. Credits can be attained for porous pavement use under categories for stormwater management (both quantity and quality), and heat island reduction. In recent times, coating materials have been introduced to the industry. These allow designers to express their creativity and ingenuity while at the same time improving pavement reflectance and capturing credit for heat island reduction. From conventional, to porous, to pattern-stamped, asphalt pavements provide flexibility and options to architects and engineers designing sustainable pavements.
Tables have been developed to show for the different LEED programs the potential credits attainable by using asphalt pavements. Each table provides the rating category, credit description, available points, and a discussion of the applicability/contribution that asphalt pavements have in attaining credits. This information has been provided for the following LEED programs:
LEED-NC Green Building Rating System For New Construction & Major Renovations Version 2.2
LEED-EB Green Building Rating System For Existing Buildings Upgrades, Operations and Maintenance Version 2
LEED for Schools For New Construction and Major Renovations April 2007 Version
LEED For Neighborhood Development PILOT VERSION Updated June 2007
LEED For Homes Program Version 1.11a January 2007
LEED For Retail – New Construction and Major Renovations Pilot Version 2 April 2007
It’s reclaimed asphalt pavement (RAP). In Ohio the asphalt industry recycles millions of tons of RAP into new asphalt pavement every year, the largest tonnage of any industry. And, asphalt's 80% recycling rate is higher than for any other material. Because this recycling is beneficial and economical, it happens without government mandates or subsidies. For more information on recycling, see the Flexible Pavements of Ohio Statement on Recycling, view the NCAT brochure, Reclaimed Asphalt Pavement FAQs, view the NAPA brochure "Take the RAP" and view the article from the Fall Issue of Ohio Asphalt on "The Case for Using Reclaimed Asphalt Pavement"
For more suggestions on ways to save money in your paving program, read the NAPA Special Report 191.
There really are manyto prefer an HMA pavement including: smoothness, quiet, stage construction, ease of maintenance, speed of construction, least user delay cost, ease of repair of utility cuts, no cure time, recyclability and now, that technology exists to design HMA mixtures to reliably perform under any conditions of load and environment, there is no longer any reason to consider anything else. For more information on
these issues, visit http://www.asphaltroads.org/
In many respects Hot Mix Asphalt (HMA) is the environmentally friendly paving material. First, HMA materials are 100% recyclable. Virtually all of the reclaimed Asphalt Pavement (RAP) that is removed from existing streets and highways is recycled into new HMA. Because this recycling of HMA is economical, it occurs without the need for government mandates or subsidies.
The use of Asphalt pavement can result in environmentally friendly, sustainable development as well. For more information on this subject visit the Asphalt Education Partnership website www.beyondroads.com and www.asphaltroads.org/Environment
HMA also has been shown to consume less energy than other materials and systems. A study done by the Asphalt Institute indicated that a comparably designed HMA pavement required only about half the total energy to construct as a comparable portland cement concrete pavement.
Improvements in technology have been steadily reducing the airborne emissions from the production and placement of HMA. Dust from the drying of aggregates is the major emission and is now almost totally captured and recycled. Other emissions are primarily combustion products from the burning of fuel to heat the aggregates and fumes from hot asphalt itself. Fuel burners are now much more efficient, resulting in very complete combustion. Studies to date by the government and industry have shown emissions levels to be very low. Nevertheless, the industry continues to develop improved technology for reducing emissions and minimizing exposure.
Articles relating to the environmental effects of HMA production:
US EPA says no HMA plant has potential to be a major source of hazardous air pollutants -HMAT, 2002.
Clearing the Air - HMAT 2001
Tests Show Low Emissions
From the Asphalt Institute:
PR-1, Environmental Applications for Hot Mix Asphalt;
RR-75-1A, Asphalt Hot Mix Emission Study;
RR-80-1, Exposure of Paving Workers to Asphalt Emissions;
IS-173, Energy Requirements for Roadway Pavements
From the National Asphalt Paving Association:
SR-166, Evaluation of Stack Emissions from HMA Facility Operations;
IS-123, PS-23, Special Report #134, Study of Paving Asphalt Fumes; and,
press release ; "Asphalt Pavement is the surprise leader in recycling---"
Highway noise is becoming a social issue with which transportation departments have to deal. Most state DOT's will build noise walls under certain circumstances in accord with federal regulations. However, in recent cases in Michigan, Pennsylvania and Arizona affected residents have demanded a change in pavement surface from concrete to quieter asphalt. The United Kingdom purposely surfaces its freeways with asphalt to reduce noise.
Many studies over the years have shown that sound produced at the tire-pavement interface with asphalt pavements lacks the level of annoying frequencies commonly generated from concrete pavement surfaces. Special asphalt surfaces, such as open-graded friction course (OGFC) and stone matrix asphalt (SMA) reduce highway noise at the source even further.
Visit the interactive pavement noise website at http://www.quietpavement.com/home.html
For more information on the issue of reducing tire/pavement noise, see visit Asphalt Additional Resources for Environment.
Warm Mix Asphalt (WMA) is a term being used to describe several different technologies that are being used to produce hot-mix asphalt (HMA) paving mixtures at significantly lower mixture and placement temperatures. Potential advantages of these technologies include: lower energy consumption; lower fumes, odors and emissions; easier placement and less aging of the binder from exposure to heat. For a complete description of this developing technology visit www.warmmixasphalt.org or the FHWA site http://www.fhwa.dot.gov/pavement/asphalt/wma.cfm
Foamed asphalt WMA is approved under ODOT specifications(Item 402.04) and is being widely used in Ohio. See the ODOT Technical Update on Foamed Warm Mix Asphalt.