High-Tech Asphalt Turns To Goo On I-84

Work was suspended on a $1 million project to seal coat 16 miles of Interstate 84 and interchanges from Meridian to Caldwell after new asphalt failed to harden, turning the freeway into a gooey mess.

Traffic - which averages about 20,000 vehicles a day on I-84 westbound - backed up for four miles and at times stopped Tuesday as cars kicked up tar and gravel.

The state announced on Wednesday that motorists whose vehicles got oil or tar on them can have the material removed for free at three Boise and two Caldwell auto detailing shops. The shops will bill the state directly.

A high-performance type of plasticized asphalt being tried in Idaho for the first time was supposed to harden quickly after it was laid Monday night on eight miles of the right-hand, westbound lane. But it did not, and Idaho Transportation Department crews began scraping it up Tuesday afternoon.

The half-inch seal coat had been laid by Kloepfer Inc. of Paul to protect the pavement against water and increase vehicle traction. Seal coats are applied every seven years.

Instead of the usual asphalt-water mixture, which takes 24 hours to set before traffic is allowed on it, a polymerized asphalt was used.

“It’s probably not a contractor problem,” Loren Thomas, a District 3 engineer for the Transportation Department, said. “It could be a materials problem.”

Thomas said the material could have had a chemical reaction with a conventional asphalt used to level the surface earlier. Tests could unearth the problem in a few days.

When the seal coating resumes, Thomas said, the same material may be used again if the contractor’s batch proved faulty.