The state Department of Transportation on Tuesday will begin a two-year, $9.1 million project to repair potholes on the H-1 Freeway airport viaduct.

The project, which focuses on a nearly three-mile stretch of the viaduct between Valkenburgh and Middle streets, will be done mostly overnight from Monday nights through Friday mornings, from 8 p.m. to 4:30 a.m., the department said. Work may also be done on Sundays during the day with initial monitoring of its effect on traffic.

Some lanes will be closed while the contractor, Triton Marine, uses a fast-forming concrete to fill in potholes, the department said. The speed limit near the repair area will also be reduced to 15 mph to minimize vibration on the viaduct while the concrete cures, the department said.

Lanes will be reopened at the end of each work shift.

"It's a little bit trickier because it's concrete potholes," said Department of Transportation spokesman Scott Ishikawa. "Up to now we've just been putting asphalt in the holes to fill it up (as a temporary patch), so we're actually going to do some permanent solutions to the potholes on the viaduct."

Ishikawa said the project involves cleaning out the potholes, fixing steel rebar and pouring in fast-forming concrete that takes about three to four hours to cure.

Ishikawa also said the state may close some lanes on Nimitz Highway directly below any repairs on the viaduct as a safety precaution.

Work is scheduled to begin Tuesday, when crews will locate areas that need repair. The actual repair work could begin Wednesday night, the department said.

About 118,000 vehicles use the H-1 viaduct each day, Ishikawa said.

"There is some wear and tear to the viaduct, and that's one of the reasons we have to repair it," he said.

"There are some pretty bad potholes closer to the Hickam (Air Force Base) side of the viaduct that need repairing."

Ishikawa noted the state already repaved Nimitz Highway from Kalihi to Downtown and will begin repaving a section of Ala Moana boulevard from the Downtown area to just past Pi'ikoi Street in the next month or so.

The viaduct repair work is "the next piece of the puzzle," he said.

The Transportation Department will provide weekly lane closure information every Friday.

Drivers are advised to use caution while driving through the work area and to allow for longer travel time. The work is weather-permitting to allow the concrete to cure.

Reach Lynda Arakawa at larakawa@honoluluadvertiser.com.