UAF researchers work on way to ease road-building costs in rural Alaska

FAIRBANKS — A possible remedy to rural Alaska’s enormous road construction costs might be sitting in a grimy plastic bin at the University of Alaska Fairbanks.

Billy Connor sifted through the bin’s contents with his hand, digging through material that looks like it came from a badly abused sandbox. There was lots of silt and sand, some thin plastic fibers and a sticky fluid that smelled like latex paint.

Connor, the director of the Alaska University Transportation Center, thinks this messy combination holds promise as a rural road of the future. It’s roughly three times stronger than silt alone and able to withstand pressures of about 175 pounds per square inch in laboratory tests. It also appears to be resistant to the freeze-thaw cycles that cause roads to buckle in permafrost-laden areas.

“We think we can cut the construction costs at least in half, maybe even more,” Connor said.

In an engineering lab inside UAF’s Duckering Building, Connor and other researchers have spent the past three years refining the mixture. Their experiments address a depressing reality in much of rural Alaska, particularly villages in Southwest. Gravel, which is great for building roads, often is unavailable. Sand and silt, which are abundant, are lousy for road construction.

In the village of Kwigillingok, located south of Bethel, Connor said gravel costs $800 per cubic yard. The material isn’t found locally, so it must be barged in from Nome, Kake or Seattle.

In response to that problem, the goal has been a simple one: figure out what it takes to make a sturdy silt road.

“That’s what engineers do,” Connor said. “They take the available materials and make them work.”

The project began when a private construction firm, Peak Civil Technologies, approached the Alaska University Transportation Center to see if cheap, lightweight plastic fibers could be substituted for gravel in roadways.

Early experiments showed promise, leading to an expanded $400,000 project paid for with state and federal transportation grants. For the past three years, researchers have worked on countless formulas before arriving at one with which they’re pleased.

The blend that seems to work best contains 0.5 percent plastic fibers by weight with the help of a substance called Soil Sement that looks like school glue. Fibrulated 2-inch-long plastic fibers seem to work best in sandy material, while tape-like plastic fibers do best at binding silt.

“We just worked our way through the rainbow until we found what worked best,” said Rodney Collins, a civil engineering graduate student who has worked for two years on the project.

Connor said the cost of the research has been high but it could reap huge rewards for the state. He figures building a runway using the process instead of gravel in Kwigillingok would recoup about four times the $400,000 investment.

Next week, the team from UAF will build a 500-foot road out of the blend near Wasilla as part of a project with the Mat-Su Borough, constructing part with an 8-inch surface and part with a 12-inch surface. If the lab results translate well into the real world and the material wears well during the next year, Connor hopes it’s included as an option in the Alaska Department of Transportation construction manual.


Read more: Fairbanks Daily News-Miner - UAF researchers work on way to ease road building costs in rural Alaska