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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Annual Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2009–2012

One of the shared goals of the Federal Highway Administration (FHWA) and the National Asphalt Pavement Association (NAPA) is to support and promote sustainable practices such as pavement recycling and warm-mix asphalt (WMA). The use of recycled materials, primarily reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS), in asphalt pavements reduces the amount of new materials required to produce asphalt mixes and material going to landfills. This is vital to the mission of environmental stewardship and extending the service life of the nation’s infrastructure while lowering overall costs. WMA technologies have been introduced to reduce the mixing and compacting temperatures for asphalt mixtures as a means of reducing emissions. Additional benefits include improved compaction of asphalt mixtures leading to improved pavement performance. As part of FHWA’s Every Day Counts initiative, WMA was chosen for accelerated deployment in federal-aid highway, state department of transportation (DOT), and local road projects. It is important for the industry to track the deployment of these technologies, which reduce costs, energy, waste, emissions, and the amount of new materials required for road construction. FHWA has established two survey mechanisms for tracking the use of recycled materials and WMA in asphalt pavements. The first survey tracks state DOT usage and the other tracks industry usage. These have established a baseline of RAP, RAS, and WMA usage and tracked the growth of the use of these sustainable practices in the highway industry since 2009. The objective of this survey is to quantify the use of recycled materials, and WMA produced by the asphalt pavement industry. Survey results show significant growth in the use of RAP, RAS, and WMA technologies from 2009 through 2012. The asphalt industry remains the country’s number-one recycler by recycling asphalt pavements at a rate of over 99 percent and almost all (98 percent) contractors/branches report using RAP in 2012. The amount of RAP used in asphalt mixtures has increased by 22 percent, from 56 million tons in 2009 to 68.3 million tons in 2012. Assuming 5 percent liquid asphalt in RAP, this represents over 3.4 million tons (19 million barrels) of asphalt binder conserved during 2012. The estimated savings at $600 per ton for asphalt binder is $2.04 billion. Use of both manufacturers’ scrap and post-consumer asphalt shingles used in asphalt mixes increased 165 percent from 2009 to nearly 1.9 million tons 2012. Assuming a conservative asphalt content of 20 percent for the RAS, this represents about 380,000 tons (2.1 million barrels) of asphalt binder conserved. The estimated savings at $600 per ton for asphalt binder is $228 million. For 2012 contractors were asked about their use of other recycled materials in asphalt mixtures. Contractors in 13 states reported using steel and blast furnace slag in asphalt mixtures. Ground tire rubber (GTR) was reported as being used in asphalt mixtures in nine states. Other recycled materials used to a lesser degree include fly ash, bottom ash, foundry slag, cellulose fiber, and glass. Due to the low response rate on other recycled materials no attempt was made to estimate the total quantities of other recycled materials used. In 2012, WMA was over 24 percent of the total asphalt mixture market. WMA use increased by nearly 26 percent from 2011 to 2012, and about 416 percent since 2009. Plant foaming is used most often in producing WMA, with over 88 percent of the market. WMA additives accounted for about 12 percent of the market.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; References; Tables;
  • Pagination: 28p

Subject/Index Terms

Filing Info

  • Accession Number: 01516367
  • Record Type: Publication
  • Report/Paper Numbers: IS-138
  • Contract Numbers: DTFH61-13-P-00074
  • Files: TRIS, ATRI, USDOT
  • Created Date: Feb 28 2014 1:32PM