Industry report

Concrete gains popularity after bump in steel prices

By Candy McCampbell

Concrete is being used more in all types of construction - 455.9 million cu. yds. was used last year in the United States, which is 6 percent more than in 2004, according to the National Ready Mixed Concrete Association.

And look for another 3 percent increase this year.

Lionel Lemay, NRCMA vice president of technical resources, said growth will come in part from the use of innovative applications of concrete, such as insulating concrete forms and pervious concrete.

Pervious concrete allows water through its surface and is gaining popularity for parking lots, especially where runoff or ground water is an issue.

"That's going to be the next big thing for our industry," Lemay said.

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Concrete is the material of choice for many buildings, primarily because of economics, said Mike Tibbett, manager of the concrete and heavy civil division of Hoar Construction in Birmingham.

Concrete is more readily available, can be enhanced with chemical additives and can be used in buildings where vibration must be minimal, he said.

Al Gogolin, structural engineer at Skanska Building USA in Atlanta, said concrete is generally faster, more fire resistant and allows for a more compact floor depth.

"That may be a few inches per floor, but on a 30-story building it adds up to a real cost factor," he said. Other factors prompting an increase in concrete use include sharp steel price increases and the greater use of concrete in housing construction.

Following are a few significant concrete projects across the south central region:

Baptist Memorial Hospital 11-Story Patient Bed Tower, Southaven, Miss. The $177 million building, in the New Madrid Fault area, is being constructed under the 2000 International Building Code, so it is structurally designed like a hospital in earthquake-prone California.

It has 20-30 percent more reinforcing steel than usual, using about 5,300 tons, said Paul Moffat, project executive with general contractor Bovis Lend Lease of Nashville.

The 450,000-sq.-ft. building is made of 3,100 cu. yds. of concrete, with shear walls that are 12 to 14 in. thick, he said.

The building sits on 20-in.-diameter piles, auger drilled 55 ft. to as much as 80 ft. for the main building, Moffat said.

The hospital design put major loads like CT scanners and MRI machines on the ground floor, where the slab on grade is 6 to 8 in. deep instead of the usual 4.5 in.

It was only wind that slowed the earthquake-resistant building last fall. High winds halted installation of precast concrete panels for about 20 days, Moffat said.

The exterior is made of decorative stone, brick and precast concrete panels.

Vanderbilt University Medical Research Building 4, Nashville. This $120 million post-tensioned concrete structure is an example of how finely tuned a 12-story, 420,000-sq.-ft. project can be.

It joins two existing buildings - one of them an auditorium - and expands upward to create additional laboratories, classrooms and offices.

Central to the project is the support from four post-tensioned, cast-in-place concrete trusses to go over Langford Auditorium, an existing four-story building.

The truss system is massive - each truss is 24 ft. tall, 140 ft. long, 5 ft. thick and requires 500 tons of concrete, said Merrill Bowers, project manager with general contractor Turner Universal Construction of Nashville.

Construction is taking longer than planned.

"The design process and interaction between the subcontract engineers and engineer of record has involved much more redesign than originally expected," Bowers said. Pouring of the trusses started in late April and should be finished by mid summer.

Other work has been progressing, such as floors and columns for the west side, installation of some precast and glazing and air chillers in the basement, Bowers said.

Jackson-Madison County Hospital, New Patient Care Tower, Jackson, Tenn. The $117 million nine-story tower is a "hybrid building" - the first three stories are reinforced concrete and the top six are structural steel, said Vince Bender, project manager with Centex Construction of Nashville.

The tower, which adds more than 356,000 sq. ft., is located between two existing patient tower buildings.

Excavation for the new tower would have exposed the footings of the present towers and the sheet piling proposed to shore them up would have caused too much vibration.

The answer: drilled shafts with permanent steel casing, placed strategically so they could serve both as shoring for the existing buildings and foundation for the new one, he said.

"By changing to a drilled pier system we were able to save 10 days on the schedule and keep the vibrations to a minimum," he added.

A tunnel links the emergency department, which is housed in the new tower, to the Central Energy Plant and laundry, he said.

Excavation for the tunnel, however, was next to the hospital loading dock. Centex built a beam and lagging shoring system so the tunnel could be built without interrupting operations at the loading dock.

Guyton Research Building Addition, University of Mississippi Medical Center, Jackson, Miss. This $43.6 million 189,000-sq.-ft., seven-story, all-concrete building doesn't sit on the clay dirt onsite.

It sits on cardboard boxes, said Mike McDonald, project manager with general contractor Flintco Inc. of Memphis.

The repeated expansion and contraction of clay prohibits structural contact, he said. "It has to sit on foam or cardboard boxes."

The medical research building addition is built on a pan joist concrete system and has additional beams to meet requirements for minimal vibration in the laboratories, he said.

Two floors are underground, meaning "waterproofing is very important," he said. Flintco used a roll-on material to waterproof the structure, plus backfilled with sand and a drain system.

About 1,600 cu. yds. of concrete will be used in the building, which will have an exterior of brick, precast concrete panels and glass. It ties into an existing four-story building.

McDonald has not had to worry about noise because there was no rock on the site, which meant no blasting, but there is no laydown space in the middle of the medical center so all deliveries had to be "just in time."

Auburn University Transportation Technology Center, Auburn, Ala. Before this $21 million building could get out of the ground, it had to get out of the water.

The finished basement floor was 8 ft. below the groundwater level so it had to be redesigned, said Kelley Pennington, vice president at general contractor Bailey-Harris Construction of Auburn, Ala.

"We needed to take out the strip footings and redesign the whole subdrainage system," he said.

The entire basement was sloped to one section so it would drain into the subdrainage system, he said. The revision "took months off the project," he added. The solution allowed workers to make up the time lost.

"Had we not implemented the solution, we'd still be there," Pennington said.

The 193,000-sq.-ft. building is constructed on pan slabs, a process that "creates beams and joists within the slab to accommodate reinforcing," he said.

The technique also allows elimination of unnecessary concrete, an estimated one-third here, Pennington said.

Concrete is being used only in the slabs and basement walls. Other walls are non-structural and made of concrete block.

One beam will be an ornate 60-in.-radius, cast-in-place concrete stair that will require some complicated forms, he said. Plans are to pour it all at once.

CCL Label Manufacturing Plant, Collierville, Tenn. There's a pressing deadline for this $12 million 111,000-sq.-ft. manufacturing/warehouse building.

Three large printing presses are to arrive from Germany in early 2007 so the structure has to be ready then, said Michael W. Brewer, executive vice president of general contractor Linkous Construction Co. Inc. of Memphis.

The floor will be a conventional slab that will be thickened to about 2 ft. deep in the press area, he said.

The tilt-up wall building is nothing new for Linkous; it has built similar buildings for year. A typical panel here will be 25 ft. wide and 30 ft. tall, the largest at 33 ft. wide and 32 ft. tall.

About 7,000 cu. yds. of concrete will be needed and about 3 lbs. of reinforcing steel per square foot of wall, so each panel will weigh 45 to 50 tons, Brewer said.

"The walls are insulated panels, with a layer of Styrofoam inside two different pours," he said. They will be poured onsite.

It takes about four weeks from time of pour to time of erection, using a crawler-type crane. Add another four weeks to get all the panels up, he said.

"Quicker, cheaper, that's the name of the game," Brewer said.

"You can pour faster and get a building up cheaper than with precast or masonry." A building like this would be up about four weeks faster, he said.

Westside Wastewater Treatment Plant, Fayetteville, Ark. This $59.9 million project is unusual because it is a completely new wastewater treatment operation "from the ground up," said Tom Marcum, project manager with Brasfield & Gorrie of Birmingham, Ala.

"There was nothing there," he said. "The transmission lines coming into the plant are being constructed as we speak." The plant consists of 27 structures that will consume 30,000 cu. yds. of concrete, which Brasfield & Gorrie is placing.

Among the structures are an operations building; inlet facilities; four biological units; four final clarifying tanks; storage units and the other tanks; holders and filters that are used to treat wastewater.

They will be connected by more than 13,000 ft. of iron pipe that is 6 to 60 in. in diameter, he said. About 3,000 tons of reinforcing steel will be needed.

The final clarifying tanks, about 110 ft. in diameter, will have 15-in.-thick walls, he said. The oval-shaped biological tanks are about the size of a football field, built in a series that runs together.

The plant, which will use an ultraviolet disinfection system, will remove all the water from the waste, leaving solids that will be hauled off.