This first article in a two-part series on recycler/stabilizers discusses their value in asphalt applications. A subsequent article will take a look at their growing use in soil stabilization, as well as discuss selection criteria for matching these machines to the application.
Reclaimer/stabilizers provide a solution to a nagging infrastructure problem. Many asphalt roads are deteriorating, and the "farm-to-market" roads are carrying loads they were never designed to handle.
Many times, road repair will be done by milling off the top layer of asphalt and replacing it with an overlay. While this can be a quick fix in certain circumstances, it does nothing to correct structural problems.
This is where reclaimer/stabilizers come in. Reclaimer/stabilizers allow the use of Full Depth Reclamation (FDR) to upgrade these surfaces. The FDR process solves many of the problems associated with reconstruction. "With a full-blown reconstruction, there can be disruption to the municipal environment and the traffic flow," says Dave Dennison, product manager - soil products, BOMAG Americas. "With reclamation, you can get in and out of there faster."
"FDR is a great tool because you can take that old road, pulverize it, blend it with cement or some other additive, widen it and you have a pretty good template to start with," says Chuck Valentine, owner of Vancouver, WA-based Valentine Resurfacing, which has been tackling FDR projects for close to 15 years. "Every instance where a county or city uses the FDR process, I can't think of one situation where they haven't had their eyes opened and said this is a really great tool."
One reason is it provides a more permanent solution to road repairs. "FDR is going to take a little more time [than mill and fill], but it is going to fix a lot more problems," says Tom Johnson, Mid-State Reclamation and Trucking, Lakeville, MN. "When you do a mill and fill, you have done nothing to take the pothole out, get rid of the crack or homogenize the mix."
John Edwards, Site-Prep of NC, Monroe, NC, adds, "If you are getting to the point where you see roads where more than 15% requires patching, it is not economically feasible to go out and patch it and overlay it. You are going to be back within a year to patch adjoining sections."
On average, a mill and fill job may last three to five years, he notes, while FDR can increase the lifespan to 15 to 20 years. "When you look at it with a life-cycle analysis, it just makes sense to do FDR," he says.
Lower material costs
Mid-State Reclamation and Trucking has been involved in FDR since 1992. "I was the first contractor in Minnesota to put a machine into service for FDR," says Johnson. "Now I have six machines and there are probably 20 machines in the state.
"FDR is one of the easiest ways to widen a road," he continues. "If the road was 22 ft. and there is room for the shoulders, we can just incorporate the shoulders and all of the mix together and put back a 24-ft. lane."
Compare this to full reconstruction, which is an expensive and time-consuming process. "We used to build the roads from the bottom up. But we don't have that kind of money, so we have to figure out how to do it from the top down," says Johnson.
By recycling the material already in place, FDR offers many economic and environmental benefits. "RAP, along with all other aggregate, has gotten to be an extremely expensive commodity," says Edwards. "Coupled with liquid asphalt prices that are bouncing between $400 and $500 a ton right now, there has never been a better time to promote FDR."
Greta Wilt, Ray Hensley Inc., Springfield, OH, agrees, noting, "I see a better market for FDR as fuel and raw material prices keep increasing." Her company started doing FDR in the early '90s. "When you use FDR, you reuse everything that you have ever put on that road. The asphalt is ground up and reused in place. You are saving landfill cost and virgin aggregate cost."