Asphalt Recycling Section
Better Roads Staff
Working in a down-cutting mode, the RX-900 feeds RAP directly into a Roadtec RT-500 mixing trailer. The mill’s conveyor places the RAP onto a JCI double-deck screen that measures 5 feet by 14 feet in size. Fully 100 percent of the material is screened to 1.25 inches minus. Oversize RAP runs through a Telsmith impact crusher aboard the mixing trailer. A return circuit runs RAP from the crusher back over the screen.
Material that passes the screen drops onto the 42-inch-wide belt with a weigh bridge on it. The weigh bridge sends a signal to the blending computer that adjusts the flow of emulsion – at a rate of 2 percent – to the pugmill mixer located in front of the machine. After a full mixing cycle, the rejuvenated RAP is discharged onto the roadway in a windrow. Roadtec says the belt scale system provides accuracy to within plus or minus 1 percent.
The construction team used Central Utah Testing and Inspection for mix design. The solventless emulsion used came from Ergon Asphalt and Emulsions.
With a windrow pickup machine, Frehner picked up the recycled asphalt and paved it back down with a Blaw Knox paver working 18 feet wide. Compaction followed, with two double-drum rollers and a pneumatic tired machine. “It turned out to be a really great project,” says Coughlin.
Once Coughlin finished the in-place recycling, the company adapted the Roadtec RT 500 mixing trailer for central plant operations. “Basically we added a mini-hopper and a couple of more belts so we could feed it with our wheel loader,” says Coughlin. The cold recycling plant added lime slurry and solventless emulsion to the RAP – in the same amounts as for the in-place recycling. Belly-dump trucks hauled the material back to the road, and Frehner paved and compacted it. Following compaction, Frehner applied a fog seal to the recycled mat. Construction started in early April and was complete by early May.
It’s a low-volume road, Thornock says. “We should see a 20-year design life,” he notes. “The only caution is that we still don’t have a great base under the road. So the cracks can reappear, and the key for us is to treat those cracks faster than we did in the past. That was the main culprit before; the cracks were not treated quickly enough.”
Take the Stockpile to the Jobsite
Traditionally, contractors applying surface treatments on pavements require multiple pavers, which often act as haul trucks for more than 70 percent of the job. The truck-and-paver rigs must make multiple trips between the off-site material stockpile and the jobsite to reload with material.
But now Bergkamp Inc., Salina, KS, has introduced the Mobile Stockpile, a fully-mobile material transfer trailer that increases the time pavers spend on paving instead of hauling. The unit reduces costs, simplifies job management and minimizes overweight truck citation risks. It eliminates the need to find off-site stockpiles — one of the biggest challenges that pavement preservation contractors face.
Standard trucks bring aggregate and emulsion directly from the supplier and load the Mobile Stockpile, which is located on the jobsite. Then, truck-mounted slurry seal or microsurfacing pavers can easily connect to it and be fully replenished with material on-site in less than 10 minutes.
Because this static stockpile is on site, multiple long-distance trips are eliminated. That way, fewer pavers can do more work in less time. The results: better allocation of workers, fewer pavers per job, less paver idle time and reduced fuel costs.
By using standard dump trucks to load the Mobile Stockpile with aggregate, and tankers for emulsion, contractors avoid the risk of receiving overweight citations due to overloaded pavers driving to the jobsite from an off-site stockpile location. Water is replenished via a tanker or hydrant through the Mobile Stockpile’s 50-foot hose reel transfer. The unit is designed to use a minimal footprint, taking just one lane-width of roadway for an entire static stockpile operation. The Mobile Stockpile is compatible with most equipment manufacturers’ slurry seal and microsurfacing pavers.
MORE FROM Featured Articles
- Sydney uses water curtains to alert drivers to stop (VIDEO)479 Views
- Rand Paul introduces bill to fund emergency transportation projects475 Views
- Tesla Model S earns top ratings from Consumer Reports428 Views
- Big four cellphone companies jointly launch anti-texting campaign261 Views
- Acceptance of connected vehicles depends on cost, LaHood says257 Views