FAIRBANKS — Like alchemists with an especially grubby laboratory, researchers at the Alaska University Transportation Center have spent the past four years working to transform powder into rock.
“We’re taking this,” said AUTC director Billy Connor, sifting a handful of dusty gray material through his fingers, “and turning it into that,” he said, tossing a cylinder of hardened earth onto a lab table with a clang.
The work, which is done at the University of Alaska Fairbanks, is about much more than curiosity. With the help of industrial binders, glues and plastic fibers, AUTC hopes that its work can transform the way roads and runways are built in rural Alaska. If they can figure out how to use local silt for roadbeds instead of barging in expensive gravel, it would save the state millions of dollars.
Connor said a road built last summer outside Wasilla offers one of the biggest reasons for optimism yet. The experimental 500-foot patch near Horseshoe Lake is notable because it isn’t made out of gravel or asphalt. It’s a combination devised by AUTC researchers of local silt, plastic fibers, solid soil binders and a liquid that looks like heavy cream.
Mixed together, they make a solid material with almost rock-like consistency.
Through the long winter, Connor was anxiously waiting to see whether the road would emerge from breakup full of pockmarks or frost heaves. The road, built with $50,000 from the Federal Highway Administration, seemed to survive the winter unscathed.
“Each year when it comes out of the snow successfully, you feel good,” Connor said with a grin.
The results are intriguing to the Alaska Department of Transportation and Public Facilities, which manages 258 airports throughout the state. The cost of maintaining those facilities in remote areas is often staggering because there’s no available source for gravel.
“A lot of those road and runways are in places where there’s no good road-building materials — there’s silt,” said Clint Adler, the DOT chief of research and development. “It’s been a big challenge for us.”
Connor said the road-surface solution used in Wasilla cost about $200 per yard, which is an eye-popping figure until the alternative is considered.
“It’s a bit pricey, but if you’re in Western Alaska where gravel costs $200 to $600 a yard to barge in, it starts sounding good,” Connor said.
By experimenting with various formulas in recent years, Connor said they’re getting closer to finding the perfect recipe. The various industrial binders tested so far include items that look like talcum powder, dry cement, white school glue and shredded plastic bags. Connor said his lab has been testing various combinations of each substance to find the ideal mix.
Various types of silt from around the state — from Kwigillingok, Fairbanks and near Tok, among other places — are also being included to see what works best to bind each together.
In lab tests, they’ve found a recipe that can bind every type of material from clay to coarse gravel, Connor said. The next stage is to figure out which ratios have the right combination of strength and affordability. He’s hopeful that some variations of the mix can eventually get down to about $65 per yard.
Adler said there’s still plenty of work that needs to be done before the silt-binding process becomes an accepted road-building material in the state. It still needs to pass a variety of real-world tests and environmental reviews before its use becomes widespread, but he said the results so far are extremely promising.
With the prospects for generous federal transportation funding looking bleaker each year, Adler said it’s crucial that state planners find cheaper methods for building and maintaining roads.
“All indications are that this technology is going to save the state a ton of money if it pans out,” he said.