With work beginning last fall and a completion deadline of June of this year, Roach Concrete, Inc. had no choice but to pour concrete in the cold of winter for the construction of a 115,000-square-foot building being built for the FedEx Corporation in Madison, Wis.

Working as the concrete subcontractor on the tilt-up construction project, Roach Concrete, Inc., Sullivan, Wis., placed more than 5,000 yards of concrete beginning in late October, and finishing in late March.

Ruedebusch Development and Construction, Madison, is doing the design-build work on the job.

The crew from Roach Concrete constructed footings, poured floors and also built tilt-up panels used to construct the walls of the building, said Phil Larsen, superintendent for Roach Concrete.

Concrete work on the job began with the construction of a casting bed for the on-site construction of the tilt-up panels used for the walls of the building.

The Roach Concrete crew poured a casting slab that ran the length of the building, approximately 300 feet in length.

"That was all machine troweled with a riding trowel. That had to be perfectly smooth. There couldn't be any blemishes on it because it was the basis of all the panels," Larsen said.

The tilt-up panels used on the FedEx job are 32 feet high, and 12 feet to 16 feet wide.

The face panels for the building are 2-1/2 inches thick, with a layer of insulation placed between the face panels and 8-inch-thick concrete structural panels.

After the casting bed was in place, Roach Concrete began concrete pours for trench footings.

"Once we got the perimeter footings on the loading dock side done, we started setting and forming walls. We were setting and forming walls, pouring walls, and pouring trench footings on the balance of the rest of the building," said Larsen.

On Deadline

Roach Concrete poured from 200 yards to 400 yards of concrete a day, reaching peaks of 1,500 yards and 2,000 yards a week for several weeks as the crew worked to meet the deadline of having the main part of the building enclosed by Jan. 1.

Roach Concrete crew did pours of approximately 20,000 square feet for the floors of the FedEx building.

"We started pouring on the south side, so we could start forming tilt-up panels. As we poured the floors, we were also casting the panels," said Larsen. "We worked our way around the building, basically in the order in which the panels were going to be erected." Larsen said.

Placement of panels began in the part of the building that had to be completed first, the area where packages are handled.

The main part of the building had to be up and heated before March 1, so that the installation of conveyors in the distribution section of the building could be finished by June 1.

The project's strict deadlines dictated Roach Concrete's approach to construction.

"Everything had to be very stringently coordinated. There were times we worked as late as 7 o'clock at night pouring footings and pouring walls so that we would be able to meet those time constraints," Larsen said.

Meeting the project's time constraints meant pouring concrete in winter, which presents another set of challenges.

For instance, in all areas in the main part of the building where tilt-up panels were going to be placed, Roach Concrete installed ground thaw tubes on the ground and poured concrete on top of the ground thaw tubes so tilt-up panels were placed on a heated slab.

"That way the panels would continue to cure, even if the temperature got below freezing," said Larsen.

Gaining Strength

Although all panels were cast before Jan. 1, when structural panels were poured, insulated blankets were placed on top of the panels to bring the panels up to the structural strength needed for the panels to be lifted.

Panels had to be at 2,500 psi in 10 days.

"If you have that 2,500 psi, you'll have a certain amount of flexural strength. If you go to the higher end, toward 4,000 psi, there's a chance you'll crack the faces. You want them to be able to stretch. There was almost no cracking of the face panels at all," said Larsen.

"When we were doing the panels, we had to adjust the mix according to the temperature so we could get them to set. Working closely with M&M, we were able to maintain a very close color for the panels. Those face panels had to be almost perfect," said Larsen.

Before floors were poured, heat tubes and blankets were put down.

"We'd pull them off the morning of the pour. We'd start our pours as early as 5 o'clock or 6 o'clock in the morning," said Larsen. "We'd try to keep the heat off, but one time we did put some heat on because it was getting pretty cold the day of the pour."

With this winter's cold temperatures, it was a challenge maintaining the concrete's heat as it was trucked to the site.

"It would even cool off by the time it got there. There were times when the temperatures were in the 20s when we were pouring concrete," said Larsen.

Because of this winter's cold, an accelerator was used in the concrete mix.

"Depending upon the external temperature, we poured anywhere between 2 percent and 6 percent of non-chloride accelerator. One section of floor we poured was 6 percent," Larsen said.

Concrete with up to 6-percent non-chloride accelerator finished fine, Larsen said.

"The test cylinder's structural strength always came up to where they were supposed to be," said Larsen.

Floor flatness was fine.

"There were no floor flatness tests, but we did some laser shots and there was little or no curling," Larsen said.

Floors were done with ride-on power trowels and a laser screed.

Founded in 1985 by Michael J. Roach, Roach Concrete's mission is to produce a quality finished concrete product along with quality service. Quality, speed and service are the company's main focus.