Sustainable Construction Using Asphalt Pavement.

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.  For more information on the sustainability of asphalt pavement visit
www.pavegreen.com and www.beyondroads.com

Some specific environmentally friendly applications of asphalt pavement are discussed in detail below:

Porous asphalt pavement used for storm water management

Asphalt Pavements and LEED^® Certification

What is America's most recycled product?

What are the advantages, other than cost, of using hot mix asphalt (HMA) pavement?

What impact does the production and use of HMA have on the environment?

How can asphalt help reduce noise pollution?   

What is Warm Mix Asphalt?

Porous asphalt pavement used for storm water management

Porous asphalt pavements are being used to reduce or eliminate storm water runoff from parking lots and other facilities.  A porous asphalt pavement is constructed over a stone filled reservoir to collect and store storm water and to allow it to infiltrate into the soil between rainfalls.  These designs can reduce pollution and replace expensive detention and treatment facilities.  Porous Pavement systems are rapidly gaining favor with designers and regulators as an economical approach to storm water management for sustainable or low-impact development. As the NPDES permit requirements have become more widely applicable, it has become necessary that developers find more innovative means of compliance.   Porous pavement systems are commonly being used as part of a strategy to obtain Leadership for Energy and Environmental Design (LEED) certification for green building projects.

A porous asphalt pavement design manual, IS-131, is available from the National Asphalt Pavement Association (NAPA)  at   www.hotmix.org/catalog/

While there you'll want to view the information in the porous pavement on-line library

An excellent article, Managing Storm Water with Porous Asphalt”, reprinted from Better Roads magazine, is available from the Asphalt Pavement Alliance at  www.asphaltalliance.com/product_list.asp

Another excellent article, " Porous Asphalt Pavement with Recharge Beds" is available at http://www.forester.net/sw_0305_porous.html

Sample specifications for the asphalt materials for the porous pavement surface and base courses follow:
Porous Asphalt Pavement Base Course (Rev.19OCT, 2007)
Porous Asphalt Pavement Surface Course (Rev.19Oct, 2007)
FHWA Technical Advisory, Open Graded Friction Courses (T 5040.31) (Dec. 26, 1990)

Other information is available at the "International Stormwater Best Management Practices Database"

For more information and articles on stormwater management using porous asphalt view the following PDF’s

Asphalt-the Right Choice for Porous Pavements

Lenexa, Kansas Tries Porous Asphalt on for Size

Thinking Green with Porous Asphalt

Porous Asphalt for Stormwater Management, It's Not Just for Parking Lots Anymore , View a presentation (PDF 8.5 MB) by Gary Thompson, PE, Training Director for the Asphalt Pavement Association of Oregon on the use of porous pavement in street construction.

View Thompson's video of the Porous Pavement Demonstration (3.6MB)

Porous Asphalt Pavement a presentation (PDF 3.9 MB) by Kent Hansen, Director of Engineering, of the National Asphalt Pavement Association on the use of porous pavement for stormwater management..

Asphalt Pavements and LEED^® Certification

Leadership in Energy and Environmental Design (LEED^®) 
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.

Earning LEED^® Certification
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.

How Asphalt Pavements Contribute to Attaining LEED^®Credits
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:      
(Click the links to view the Tables, PDF format)

• 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

What is America's most recycled product?

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 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.

What are the advantages, other than cost, of using hot mix asphalt (HMA) pavement?

 There really are many reasons to 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 the website of the asphalt alliance.

What impact does the production and use of HMA have on the environment?

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.pavegreen.com

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.

To read articles relating to the environmental effects of HMA production, click on the following PDF links:

• 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 very low emissions from silos and truck load out.

For more information on this subject see the following publications of 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

and of 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---"

How can asphalt help reduce noise pollution?

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 the following references:

1) article by Wayne Jones, PE, "Highway Noise Control With HMA", printed in Asphalt Magazine, Fall 2002 This article is available on line at www.asphaltalliance.com/library.asp?MENU=14

2) article by P.S. Kandahl, PE, "Asphalt Pavements Mitigate Tire/Pavement Noise", printed in Hot Mix Asphalt Technology Magazine, March/April 2004

3) NCHRP Synthesis of Highway Practice 268, "Relationship between Pavement Surface Texture and Highway Traffic Noise", R. Wayson, et al, 1998, published by the Transportation Research Board of the National Research Council and available for purchase at http://trb.org/bookstore/

4) Final Report, "Effects of Pavement Type on Traffic Noise Levels", March 2000, Herman and Ambroziak, Ohio University, Ohio Research Institute for Transportation and the Environment, http://webce.ent.ohiou.edu/orite/NA.html

5) Purdue University, Institute for Safe, Quiet and Durable Highways, http://widget.ecn.purdue.edu/~sqdh/

6) Asphalt Alliance website, "Asphalt, the Quiet Pavement", www.asphaltalliance.com/library.asp?MENU=14

What is Warm Mix Asphalt? 

Warm Mix Asphalt (WMA) is a term being used to describe several different, developing  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

You will also be interested in the discussions of Warm Mix Asphalt in the Spring, 2006 issue of Ohio Asphalt magazine and you will want to view the presentations presented at the Ohio "Warm Mix Asphalt Technologies Field Trial/Open House, September 12, 2006.