A shared goal of the Federal Highway Administration (FHWA) and the National Asphalt Pavement Association (NAPA) is to support and promote sustainable practices, such as the use of recycled materials and warm-mix asphalt (WMA). The use of recycled materials, primarily reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS), in asphalt pavements conserves raw materials and reduces overall asphalt mixture costs, as well as reduces the stream of material going into landfills.
WMA technologies have been introduced to reduce production and compaction temperatures for asphalt mixtures, which reduces the energy needed and emissions associated with mixture production. Additional benefits include improved low-temperature compaction of asphalt mixtures leading to improved pavement performance, as well as a longer paving season. WMA was chosen for accelerated deployment in federal-aid highway, state department of transportation, and local road projects as part of FHWA’s 2010 Every Day Counts initiative.
The objective of this survey, first conducted for the 2009 and 2010 construction seasons, is to quantify recycled materials used and WMA produced annually by the asphalt pavement industry to document the deployment of these technologies to understand where they are being used and where they are underutilized. Results show significant growth in the use of RAP, RAS, and WMA technologies since 2009, although the rate of year-over-year growth has generally slowed since 2013.
The asphalt industry remains the country’s most diligent recycler with more than 99 percent of reclaimed asphalt pavement being put back to use. The average percentage of RAP used in asphalt mixtures has increased from 15.6 percent in 2009 to 20.5 percent in 2016. In 2016, the estimated RAP tonnage used in asphalt mixtures was 76.9 million tons. This represents more than 3.8 million tons (21.5 million barrels) of asphalt binder conserved, along with the replacement of some 73 million tons of virgin aggregate.
Similarly, the use of RAS in asphalt pavement mixtures has increased from 701,000 tons in 2009 to an estimated 1.39 million tons in 2016; however, the use of RAS declined significantly (27.9 percent) from 2015 to 2016.
The combined savings of asphalt binder and aggregate from using RAP and RAS in asphalt mixtures is estimated at more than $2.1 billion.
More than 768,000 tons of other recycled materials were reported as being incorporated into nearly 6.5 million tons of asphalt pavement mixtures during the 2016 construction season, including ground tire rubber, blast furnace slag, steel slag, and cellulose fibers.
The estimated total production of WMA for the 2016 construction season was 116.8 million tons. This was a decline of 2.5 percent from the estimated 119.8 million tons of WMA in 2015, due largely to a 10.2 million ton decrease in DOT tonnage for the year, but is still a greater than 595 percent increase from the estimated 16.8 million tons in the 2009 construction season. WMA made up 31.2 percent of the total estimated asphalt mixture market in 2016. Production Plant foaming, representing nearly 77 percent of the market, is the most commonly used warm-mix technology; chemical additive technologies accounted for a little more than 21 percent of the market.