In a survey of the use of recycled materials and warm-mix asphalt usage by the U.S. asphalt pavement industry, nearly a quarter of all asphalt mixtures produced in the 2012 construction season used warm-mix asphalt (WMA) technologies.
The survey, conducted by the National Asphalt Pavement Association (NAPA) under contract to the Federal Highway Administration (FHWA), found that the 1,141 U.S. asphalt plants queried produced about 86.7 million tons of WMA during the 2012 construction season. This marks a 416 percent increase in the use of warm mix since the survey was first conducted in 2009.
Because WMA is produced at a lower temperature than traditional asphalt mixes, it uses less energy to produce, reduces emissions, improves worker safety and offers construction benefits. U.S. Secretary of Transportation Anthony Foxx commented in January during the 2014 Transportation Research Board Annual Meeting that the use of WMA is expected to save $3.6 billion in energy costs alone by 2020.
Asphalt pavements also use increasing amounts of recycled materials. The survey found that 68.3 million tons of reclaimed asphalt pavement (RAP) and 1.86 million tons of recycled asphalt shingles (RAS) were used in new asphalt pavement mixes in 2012. For the first time since the start of this survey in 2009, the amount of RAP and RAS used by producers exceeded the amount collected.
The use of RAP and RAS during the 2012 paving season translates to a savings of 21.2 million barrels of liquid asphalt binder, saving taxpayers some $2.2 billion. 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.
Compared to previous surveys, conducted annually since the 2009 construction season, the use of recycled materials has continued to increase.
In 2012, RAS usage reached 1.86 million tons – a 56 percent increase over 2011, and a 165 percent increase since 2009. Since 2009, RAS usage has been reported in 37 states. RAS includes both manufacturer scrap shingles and post-consumer roofing shingles.
RAP usage also continued to climb, increasing to 68.3 million tons in 2012, a nearly 22 percent increase from 2009. More than 99 percent of asphalt pavement reclaimed from roads went back into new roads. In the survey, 98 percent of producers reported using RAP in their mixes.
The 2012 survey also asked for the first time about the use of ground tire rubber, steel and blast furnace slags, and other recycled materials. Although national estimates of these products’ usage were not calculated, more than 1 million tons of other recycled materials was reported as being incorporated into asphalt mixtures.
Published in the March 2014 Edition of American Recycler News