The state Department of Transportation is warning drivers about construction on the H-1 freeway airport viaduct that could also affect traffic on Nimitz Highway during weekends for the rest of this year, all of next year and into 2016.

DOT spokeswoman Caroline Sluyter said work crews are repairing about 96,000 square feet of damaged concrete along 3 miles of roadway. Repairs to the viaduct, which was built in the 1970s, is part of the department’s goal to improve the state’s major highway corridors.

The $15.6-million project, which began in April, is being done only on weekends to reduce traffic congestion, but that is stretching the length of the project to 2016.

Construction starts on Friday nights and lasts through Sunday nights, closing a couple lanes at a time.

In the area of construction, the speed limit will be reduced to protect motorists and workers, and reduce vibrations that could damage quick-drying concrete, Sluyter said during a media tour of the repair work Saturday.

She said there will also be lane closures on Nimitz below the deck even though it may look like no work is being done there. The closures protect drivers in case any high-pressure water from the repair work above blasts through the deck.

All ramps to the airport will remain open.

A Goodfellow Bros. project superintendent, who declined to give his name, said crews found the damaged areas using the "chain and hammer" method, which turned out to be better than the high-tech equipment.

The chain-and-hammer technique involves a worker dragging a heavy chain from side to side across the concrete, which produced a noticeably hollow sound in damaged areas. The hammer helps to home in on fractures.

It took about two months just to map out the damaged areas.

Workers are blasting away concrete in the damaged areas with a hydro-demolition machine, which forces water into voids in the concrete using 15,000 pounds per square inch of pressure. The water expands in the voids and breaks up the material — all while leaving the rebar undamaged.

Up to 4 inches of concrete is removed from the 8-inch-thick deck, then fast-setting concrete is laid to complete the repair. A concrete sealer will be applied to prolong the life of the roadway, the DOT said.

Federal funds are covering 80 percent of the project’s costs, and the state is paying for the rest.