Asphalt: The Green Paving Choice
Not only does asphalt provide the smoothest, quiet ride, it also is the most sustainable option for paving. Over the years, the asphalt pavement industry has been a constant innovator in finding ways to make its products more environmentally friendly — from reclaiming old asphalt pavements and rejuvenating their component parts for use in new pavements to the incorporation of recycled materials to the adoption of energy-saving warm-mix asphalt technologies.
As early as 1993, the Environmental Protection Agency and Federal Highway Administration identified asphalt pavement as America's No. 1 recycled product in a report to Congress. It continues to be reclaimed and reused at a greater rate than any other product in the U.S. A wide range of waste materials are now incorporated into asphalt pavements, including ground tire rubber, glass, foundry sand, slag, and even pig manure, but the most widely used are reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS). The use of recycled materials in asphalt pavements saves hundreds of millions of cubic yards of landfill space each year.
NAPA, in partnership with the Federal Highway Administration (FHWA), is quantifying the use of these technologies through industry surveys. According to the latest survey data, during the 2013 construction season more than 67.8 million tons of RAP and nearly 1.65 million tons of RAS were put to use in new pavements in the United States, saving taxpayers more than $2 billion. Also, more than 30 percent of all asphalt produced in the country that year was made using warm-mix asphalt (WMA) technologies.
When reclaimed asphalt pavement and shingles are reprocessed into new pavement mixtures, the liquid asphalt binder in the recycled material is reactivated, reducing the need for virgin asphalt binder. Using reclaimed materials also reduces demands on aggregate resources. Warm-mix asphalt technologies allow asphalt pavements to be produced at lower temperatures, which means reduced energy demands, as well as lower emissions during production and paving.
Compared to previous FHWA/NAPA surveys covering the 2009–2012 construction seasons, the use of these sustainable practices has continued to increase.
In 2013, RAP usage reached about 67.8 million tons, a 21 percent increase from 2009. More than 99 percent of asphalt pavement reclaimed from roads and parking lots was reclaimed for use in new pavements instead of going into landfills. In the survey, 100 percent of producers reported using RAP in their mixes for new construction, pavement preservation, rehabilitation, and other projects.
RAS usage also continued to be strong, reaching to nearly 1.65 million tons in 2012 — a nearly 135 percent increase since 2009. Since 2009, RAS usage has been reported in 41 states. RAS includes both manufacturers' scrap shingles and post-consumer roofing shingles.
Producers were also asked about ground tire rubber, steel and blast furnace slag, and other waste material repurposed into pavements. Although national estimates of usage were not calculated, survey respondents reported using nearly 1.2 million tons of these materials in 2013 in the production of 6.6 million tons of asphalt paving mixtures.
In 2010, FHWA made warm-mix asphalt part of its Every Day Counts initiative to speed the deployment of technologies that can improve highway projects' quality, sustainability, and safety. In 2013, NAPA and FHWA were honored by the Construction Innovation Forum, earning a NOVA Award for their work promoting the uptake of WMA.
In 2013, total WMA tonnage in the U.S. was estimated at about 106.4 million tons, a 23 percent increase from 2012 and a greater than 533 percent increase since 2009. Most WMA in the U.S. was produced using a plant foaming process, which injects a small amount of water into the mix; warm-mix additive technologies accounted for a little more than 13 percent of the WMA tons produced.
The full report and related materials, including a state-by-state breakdown of recycled materials usage, can be downloaded below:
- IS 138 Executive Summary (2 pages)
- IS 138 Full Report (26 pages)
- Appendix A (Survey Forms) (15 pages)
- Appendix B (State-by-State RAP, RAS, WMA Usage) (54 pages)