The use of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) in new road mixes can help road owners conserve raw materials and reduce overall asphalt mixture costs during construction.
To better gauge how widespread the use of these recycled materials are in new mixes, the National Asphalt Pavement Association (NAPA) in partnership with the Federal Highway Administration (FHWA) conducted a survey of asphalt mixture producers across the United States on tons produced, along with a survey of state asphalt pavement associations (SAPAs) regarding total tons of asphalt pavement mixture produced in their state for the 2019 construction season. These results were compiled in the association’s September 2020 report, “Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage 2019.”
Asphalt mixture producers from 48 states, Guam, and the District of Columbia completed the survey. In total, 212 companies and 1,101 production plants shared their insights.
According to the survey, more than 94 percent of asphalt mixture reclaimed from old asphalt pavements was put back to use in new pavements in 2019. The remaining 6 percent was used in other civil engineering applications, such as for unbound aggregate bases. This fact makes “asphalt mixture producers … the country’s most diligent recyclers,” according to the NAPA report.
In 2019, companies reported accepting 97 million tons of RAP. The survey found that the overwhelming majority of RAP is used in hot-mix asphalt (HMA) or warm-mix asphalt (WMA) mixtures, which NAPA says is the most optimal use of the material.
From 2018 to 2019, the survey found that the amount of RAP used in HMA or WMA mixtures increased from 82.2 million tons to 89.2 million tons. The use of 89.2 million tons of RAP in 2019 represented a nearly 59.3 percent increase from the total estimated tons of RAP used in 2009, which was the first year NAPA conducted its annual survey. As reference, total asphalt mixture tonnage has increased only 17.7 percent since 2009.
The survey also showed that the average percentage of RAP used in asphalt mixtures remained at 21.1 percent nationwide from 2018 to 2019. The states with the highest average estimated percentage of RAP used in 2019 included Ohio (32 percent); Florida (31 percent); Maryland (30 percent); Michigan (29 percent); and Utah and Virginia (28 percent). The states with the lowest average estimated percentage of RAP used in 2019 included Arizona (9 percent); Arkansas and Pennsylvania (13 percent); and California, Kentucky, Massachusetts and Texas (16 percent).
In 2019, more RAP was received by asphalt mix producers than was used, resulting in stockpiles. For 2019, 93.9 percent of producers reported having stockpiled RAP, which was down 0.6 percent from 2018. The estimated amount of RAP stockpiled, however, increased to 138.04 million tons across the U.S. This represented a 20 percent increase from the 110.31 million tons of RAP estimated to be stockpiled from the prior year’s period. The reported RAP stockpiled in 2019 represented about 1.5 years of inventory at 2019 utilization levels, NAPA notes.
Finally, the average percentage of RAP mixtures incorporating softer binders was 18 percent during 2019, which was down from 20 percent in the 2018 survey. However, NAPA notes that this data is highly dependent upon the companies responding to the survey, and not necessarily reflective of statewide percentages. The percentage of RAP mixtures incorporating recycling agents remained at 4 percent from 2018 to 2019.
Regarding RAS and other recycling findings, the report offered the following highlights:
• The total estimated tons of RAS used in asphalt mixtures decreased 12.5 percent to an estimated 921,000 tons in 2019. This reversed the increase in the use of RAS reported during the 2018 construction season, with utilization roughly 53 percent below the 2014 peak level of reported usage.
• The total estimated amount of RAS stockpiled nationwide at the end of the 2019 construction season was about 1.14 million tons, a 16.5 percent decrease from 2018.
• RAS usage during the 2019 construction season is estimated to have reduced the need for 184,200 tons (more than 1 million barrels) of asphalt binder and about 460,000 tons of aggregate with a total estimated value of more than $103 million.
• Reclaiming 611,000 tons of unprocessed RAS for future use saved about 370,000 cubic yards of landfill space, and more than $33 million in gate fees for disposal in landfills.
• The use of softer binders and recycling agents with mixtures incorporating RAP and RAS was reported nationwide. There was little correlation between the level of RAP and RAS used and the use of softer binders and/or recycling agents.
• Other recycled materials commonly reported as being used in asphalt mixtures during the 2019 construction season were recycled tire rubber, blast furnace slag, steel slag, cellulose fibers and fly ash.
• Nearly 1.3 million tons of other recycled materials were reported as being used in nearly 8.3 million tons of asphalt mixtures by 52 companies in 24 states during the 2019 construction season.
The full “Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage 2019” report is available online.
