On Route 101 in Candia-Auburn stretch, the rubber is the road
CANDIA - For commuters, the repaving of Route 101 through Auburn and Candia over the past year has been a pain in the bumper.
But to folks at the state Department of Transportation, the $13.4 million, 7.2-mile project, which is nearing completion, is paved with innovation and ingenuity.
Eric Thibodeau, pavement management chief in DOT's materials and research bureau, said the project "really showcases recycled materials and what we can do with them."
"It's not business as usual anymore," he said. "We're looking at different things and trying to be cost-effective as much as possible."
Forty percent of the new road's surface consists of what transportation geeks call "RAP" - recycled asphalt pavement - that was ground off the existing road, processed and then used to repave the same stretch.
On a typical road project, the RAP content is about 22 percent.
The work also generated 10,000 tons of excess RAP; DOT already has used half of that to repave Chester Road in Candia.
The 101 project is a sort of real-world experiment for the DOT, which used different paving mixes on three separate road sections.
About three miles are paved with what DOT calls an ARGG - asphalt rubber gap graded - mix, which contains RAP and recycled rubber from about 35,000 scrap tires.
"It's where the rubber is the road," quipped Ron Simbari, director of marketing for All States Materials Group.
His company blended "crumb" rubber from the tires with liquid asphalt that contractor Pike Industries used to make the ARGG mix.
Another 3.5-mile stretch is paved with "high-polymer modified asphalt," designed to increase durability and resist cracking. And DOT used its conventional asphalt mix on about eight-tenths of a mile.
That conventional asphalt typically lasts eight to 10 years, Thibodeau said. "After that, we need to come back and resurface the road again."
The Auburn-Candia section of 101 was last paved in 1999. DOT hopes the new paving mixes will add years to the road's lifespan.
"All the different pavement treatments are tools in a toolbox," Thibodeau said.
"We'll be comparing performance against each other to look at the life cycle cost. If we can get in this 15-year cycle versus a 10-year cycle, that's a big savings," he said.
Simbari said the asphalt industry leads all others when it comes to recycling materials.
"I think we're viewed as not green," he said, "where by far, we're the world's leading recycler."
And there's no tradeoff in quality, he said. "It's the best of both worlds. Sometimes recycled products do compromise performance, but in this case, it enhances it."
Denis Boisvert, DOT's chief of materials technology, said the goal is to come up with a road surface that combines strength with elasticity.
"The road's a rubber band out there," he explained. "When it gets cold enough, it can't stretch anymore, and it cracks."
That's where he hopes the rubber tires and high-polymer mixes come in.
Drivers may even notice the difference.
Engineers say the ARGG mix will reduce tire spray and hydroplaning during storms. The new pavement also should cut down on tire noise; DOT plans to measure and compare tire noise on the new sections this week.
Using more recycled materials also makes economic sense, Thibodeau said, with the cost of new asphalt rising 450 percent over the last 20 years due to the price of petroleum.
There are other innovations on the new stretch of 101, such as the beveled "safety edge" that helps drivers maintain control if they go off the shoulder and try to get back on the pavement. It's been used before, on secondary roads, but this is the first major New Hampshire highway to have these new edges.
DOT is also using new "warm mix" technology that saves energy, reduces fumes and extends the paving season.
All this innovation earned the state a $2 million federal "Highways for Life" grant to help pay for the project. The DOT also just won a national award for "excellence in pavement preservation."
Using specialized mixes is not new to highway design, Boisvert said, but it's new for New Hampshire.
"We're all pretty conservative," he said. "If you reach out and try something that doesn't work, taxpayers don't like that."
That $2 million grant helped convince DOT engineers to try them out on the 101 project. The remaining $11.4 million cost was an 80-20 federal/state mix.
It's not just the cost of materials that comes into play. Boisvert noted if the road surface lasts longer, that means less construction in New Hampshire's future.
"The less frequently we're out there doing work, the safer we all are," he said.
Steve Quirion is DOT's contractor administrator for the 101 project.
Quirion, who speaks in mile markers instead of towns, has practically been living on 101 since the current project started last August. He's at the DOT patrol shed in Candia at 7 a.m., works until 3:30 p.m., and then returns by 7 p.m. to monitor the night work until about midnight.
He said all work in the Auburn-Candia corridor will be done within two weeks.
Next up? Paving a 5.8-mile stretch from Candia to Epping starts next year and finishes in 2015.