Imports of cement through Hampton Roads more than tripled last year as builders' demand for the key ingredient sold out domestic manufacturers.

At Hampton Roads, the 10th-largest cement import point in the nation, imports of 121,000 tons in 1993 expanded to 418,000 tons in 1994, according to the Portland Cement Association.U.S. consumption of cement hit a record of 94.1 million tons last year, according to the cement association. Of that, about 12.4 million tons were imported.

A booming construction market for new homes, roads and schools in Tidewater, the rest of Virginia and North Carolina is driving demand for cement imports here.

"Our business really goes around housing," said Ed Fiorella, terminal manager for a Lehigh Portland Cement Co. facility adjacent to Norfolk International Terminals. "When construction is booming, our business is booming."

Demand is so strong that Roanoke Cement Co. is doubling the holding capacity of its terminal on the Elizabeth River, said Kevin Tuohy, a Roanoke Cement vice president.

Roanoke Cement, a joint venture of Greece-based Titan Cement Co. and England-based Tarmac PLC, makes 1 million tons of cement a year at a plant north of Roanoke. It supplements that supply with imports of Greek cement shipped to its terminal in the South Norfolk section of Chesapeake.

Roanoke Cement is investing about $3 million to double the capacity of its terminal to 42,000 tons from 20,000 tons, Mr. Tuohy said. The expansion is supposed to be completed by October.

It expects at least 13 cement-laden ships to call at its terminal this year, up from a handful last year, Mr. Tuohy said.

At Blue Circle Cement Co.'s Chesapeake terminal last week, the steel deck of the Greek bulker Nea Alpis reverberated as a front-end loader deep inside its No. 4 hold pounded on the ship's side.

A yellow tractor was coated with the gray-white dust as it tried to shake the cement from the 32,000-ton vessel's ribs. The dust billowed out of the hold, coating the deck and ship's laborers.

Cement arriving at Blue Circle is bored out of a ship's hold by a screw attached to the long arm of an awkward-looking, crane-like machine on a barge beside the ship. It is then sucked into a bin on the barge, pressurized and blown out through long pipes into one of the 16 150-foot-tall silos dwarfing the southern branch of the Elizabeth River.

The Nea Alpis planned to unload 18,000 tons of cement, about half Blue Circle's silo capacity, over six days.

A few years ago, most of the cement the Blue Circle and Lehigh terminals handled was made in domestic plants and barged to Hampton Roads for distribution by truck or rail.

Blue Circle's terminal was constructed in the early 1960s by what was then Atlantic Cement Co. to serve as the local distribution point for a cement plant in Ravena, N.Y. That plant, with a 1.5 million-ton capacity, still serves the terminal here and others in Boston; Bayonne, N.J.; Baltimore; Savannah, Ga.; and Jacksonville, Fla.

Lehigh was supplied by barge from plants in Maryland, but right now nearly all its cement originates from overseas, Mr. Fiorella said.

"The only reason people import cement is their own manufacturing plants are sold out," he said.

The terminal, owned by Germany's Heidelberg Cement Co., will see its business reach about 200,000 tons a year from half that a few years ago, Mr. Fiorella said.