Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/473140
Technology, was on the trip. "I don't think we're going to change the [U.S.] industry to make it the way they do things in Japan, but one of the things that is well rooted in Japan, and is only beginning here, is the use of rejuvenators." A rejuvenator is an asphalt-like, low-viscosity binding material that interacts with the old binder in the RAP to restore its properties. When Japanese contractors use high-RAP contents in their asphalt mixes, they preheat the RAP then add the reju- venators to the hot RAP to give the rejuvenator time to interact with the RAP binder before mixing with the virgin asphalt and aggregate. According to West, rejuvenators have only been used on an experi- mental scale in the United States. There are a number of companies selling rejuvenators and other materials coming into the market, but most are fairly new. NCAT and other research organizations are evaluating the different rejuvena- tors to see how well they work. If they prove successful with RAP, they could be used with reclaimed asphalt shingles as well. An education session at NAPA's annual convention in January cov- ered the information gathered from the trip to Japan. Anyone who was unable to attend the convention will be able to find information about the trip in a publication that should be available this summer. NCAT is also working on a RAP project for the Virginia DOT at its test track in Alabama. The project involves doing a bit of stabilization to 100-percent RAP and using it as a base material. "There are a number of differ- ent ways to stabilize it, but Virginia decided on foamed asphalt stabi- lization," West says. "For the test track experiments, we ran the RAP through a small portable plant and add about 2 percent of the foamed asphalt along with approximately 1 percent of Portland cement. That material was then hauled to the paving site and placed cold, but paved with conventional paving equipment and rolled with regular rollers. The material behaves a lot like hot-mix asphalt in pavement response, and it is a pretty low-cost material where there is an excess supply of RAP. The test track sec- tion is proving that it is a very reli- able option where there are excess quantities of RAP, which is com- mon in large metropolitan areas. That's a trend that is catching on in Virginia." Porous asphalt Porous asphalt is a type of perme- able pavement, which is becoming more popular in areas where help is needed with water drainage. Though similar in appearance, porous asphalt EquipmentWorld.com | March 2015 59 A section of the NCAT test track is paved with asphalt containing 45 percent RAP. Porous asphalt is a full-depth permeable pavement that has become popular in areas where water runoff is an issue.