Recycling asphalt pavement makes both environmental and economic sense. Reclaimed asphalt pavement constitutes a “treasure trove” of pre-processed road-building materials. The use of recycled asphalt pavement has grown widely, reducing the use of virgin materials and helping to preserve landfill space. Highway agencies and taxpayers benefit because recycling stretches tax dollars, allowing more roads to be kept in better condition.
Reclaimed asphalt pavement (RAP) is the term given to removed and/or processed materials containing asphalt and aggregates. These materials are generated when asphalt pavements are removed for construction, resurfacing, or to obtain access to buried utilities. When properly crushed and screened, RAP consists of high- quality, well-graded aggregates coated by asphalt cement.
The HMA industry has been recycling on a large scale since the 1970s Oil Embargo. Research on mix properties and modifications to plant equipment were quickly done in response to the asphalt shortages at that time, and within a few years, recycling became a commonplace practice. Over the years, contractors generally stuck with having one stockpile of recycled material and feeding anywhere from 10 to 25 percent RAP into the mix. This produced significant cost savings, and the industry was content to remain at this level of recycling.
It is time to consider means for increasing RAP content even further. RAP is a resource rich in asphalt and aggregate, and just as we test and process virgin materials, so too should we judge the quality of RAP and process it.