Concrete update

Despite rising cost, material still popular option on South Central jobs

By Candy McCampbell

Cost-effective and environmentally friendly concrete continues to be a popular building material throughout the South Central region.

In use since before the Romans built aqueducts in France, concrete is currently going into South Central projects as diverse as a Little Rock hospital, a Gulfside condo tower, a Beale Street hotel and a Birmingham church activity center.

"You can color, stamp, stain, mold and form unique structures out of concrete that have many other attributes," said Heather Brown, interim director of the Concrete Industry Management Program at Middle Tennessee State University in Murfreesboro.

"It is sound, wind and earthquake resistant," Brown said. And its energy efficiency is "key to consumers."

Concrete is "earth-friendly," said Robert Varner, executive director of the Mississippi Concrete Industries Association.

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Its cement, sand and water base are "abundant natural resources" and, after use, concrete can be broken up and re-used for things such as base material for roads, he said.

It's also low-maintenance, said John Eggers, senior concrete research engineer at the Louisiana Transportation Research Center in Baton Rouge.

"Properly constructed concrete structures also do not require the maintenance or protection from the elements that steel would require," he added.

Concrete's higher use also comes from the additives to the "mix."

"We can now pour concrete in extreme weather, underwater, 30 floors up or in tight spaces where equipment or manpower can not go," Brown said.

In addition, when cement is scarce "a myriad of cementitious byproducts can allow the structure to be at the same performance [level] but cost a little less and help the environment."

The main reason for concrete's popularity is that "it is the most economical material for most large structures," Eggers said.

Sure, prices are higher, but that is happening across the supply board, Brown said.

"If all costs were equal, concrete would still be at the top of the list because of the durability and life you can achieve out of concrete," she said.

As prices of cement rise, look for greater use of fly ash and slag to replace it while adding strength to concrete, Eggers said.

"Both slag and fly ash are cheaper pound for pound than cement," he said.

They have become increasingly popular in recent decades as a cost-cutter and as owners seek stronger and more durable material.

Meanwhile, concrete supplies have been tight because of domestic plant shutdowns for maintenance and demand from China, which is gearing up for the 2008 Olympic games.

"All the rebuilding and growth will have some impact on demand," Varner said.

Concrete consumption has been up this year, but the Portland Cement Association recently revised its forecast downward, projecting 2.3 percent growth over last year due to higher interest rates, higher oil prices and inflation. It earlier predicted a 3.5 percent increase in consumption.

Following are some of the larger projects currently under way in the South Central region.

Turquoise Place, Towers I and II, Orange Beach, Ala. The $110 million Turquoise Place, Tower I, in Orange Beach, Ala., will soon top out and work is starting on Tower II.

Housing 400 luxury condominiums, Tower I will be 304 ft. tall and Tower II will rise to 377 ft., said George Yates, project manager with general contractor Yates Construction of Biloxi, Miss.

With floor slabs in the 33,000-sq.-ft. to 35,000-sq.-ft. range, the buildings will require about 110,000 cu. yds. of concrete.

The buildings have post-tensioned decks and concrete and rebar columns and sheer walls.

The towers sit on 20-in. auger-cast compression and tension piles that were drilled about 65 ft. to a sand layer, he said.

Each tower is fronted with a four-story parking garage. Exterior walls will be a glass curtain wall extension of turquoise glass.

Applied Sciences Building, The University of Alabama, Huntsville, Ala. More than 1,000 rammed aggregate piers, driven down about 30 ft. to rock, support this $60 million four-story, 207,000-sq.-ft. building.

The procedure was quicker than building concrete caissons, and saved both money and about one month of construction time, said Marty Miller, project manager with construction manager Turner Universal of Huntsville, Ala.

An early surprise was a "subterranean void" that - thanks to designs by the geotechnical and structural engineers - got an injection of pressurized grouting, he said.

The cast-in-place concrete building has pan joist floors with 4.5-in. slabs.

The building will house laboratories, so 100 lab fume hoods and a dedicated laboratory exhaust system were installed. Supply and exhaust systems also have redundant fans, he said. The lab exhaust system has a heat recovery system to pre-cool outside air and lower air-conditioning energy consumption.

The exterior walls are limestone, precast concrete and granite with curtain wall windows. The roof is SBS modified bitumen membrane.

Monolithic dome activity center, Faith Chapel Christian Center, Birmingham, Ala. Build six round forms, cover each with roofing membrane, inflate that and start spraying inside with layers of shotcrete and insulating foam.

Constructing the six domes in this $16.5 million church expansion project is almost that simple, said William Robertson, construction manager with Monumental Contracting Service of Birmingham, Ala. It's a little more detailed - the domes must be lined with rebar and interiors must be finished out.

The domes range in size from 27,228 sq. ft. to 14,952 sq. ft., and will require 3,450 cu. yds. of concrete and 330 tons of steel.

One dome goes up about every two months, he said. When all six are finished, subs will start on the interiors, moving directly from one to the next.

The base walls - from 10 ft. to 14 ft. tall - are built in much the same way as the dome. The wall form is lined with the woven rebar and sprayed with shotcrete and insulating polyurethane foam.

Parking deck, Arkansas Children's Hospital, Little Rock. When the building site is surrounded by city streets and other buildings, it makes sense to pre-build elements offsite and assemble them after delivery.

That's what is happening at this $12 million, four-level parking deck, said Larry Beckius, vice president for facilities at the hospital. "It's put together like Lincoln Logs."

The project's general contractor is Nabholz Construction of Conway, Ark.

The columns and beams are all precast and trucked in from Oklahoma and Texas, and columns are bolted in place.

The floors are post-tensioned concrete.

The parking deck, next to a hospital-related office building, is four separate and unconnected levels, each entered from one of the surrounding streets in the hilly city. Its 1,000 spaces will be assigned for hospital employees.

The foundation is 151 drill piers, sunk about 25 ft., he said.

The floors were being poured in August, at a rate of about 24,000 cu. yds. a week. The structure will use about 111,000 cu. yds. of concrete and 600 tons of reinforcing steel. Walls more than 8 ft. tall are 12 in. thick, while shorter ones are 8 in.

Hospital addition, University of Arkansas for Medical Sciences, Little Rock. This massive $150 million hospital project - actually a replacement for the existing hospital -- includes an 11-story patient tower, a four-level underground parking deck and a five-story Psychiatric Research Institute.

Half of the 11-story tower is built on grade and half is built over the parking deck that will hold 1,000 cars, said Keith Jacks, vice president and project executive of general contractor CDI.

The patient care building contains 558,000 sq. ft., the psychiatric building 100,000 sq. ft. and the reinforced concrete parking deck 420,000 sq. ft., he said.

With space for 240 patient rooms, the hospital sits on a drill pier foundation. "Because the parking deck goes down 40 ft., we were already into rock," he said.

The hospital addition will consume 4,000 tons of steel and 43,000 cu. yds. of concrete. A heliport will sit atop the tower.

The exterior will be a glass curtain wall and brick masonry with accent composite metal panels.

Peabody Hill mixed-use dining hall, Vanderbilt University, Nashville. The oval-shaped atrium is open to all three floors and curved concrete stairs connecting each floor are part of the structure of this $29.3 million 115,000-sq.-ft. building.

The atrium brings a couple of challenges, starting with scaffolding that has to rise from the main floor to the roof, said Ed Bullington, vice president and group manager at Hardaway, the project's general contractor.

The other is the smoke evacuation system designed to work in the open area.

The building has post-tensioned beams, and floors are conventional slabs with rebar-reinforced concrete. The post-tensioned beams can provide the same support with shallower beams, he said.

The exterior will be brick and limestone.

The roof will be covered by a TPO, or thermoplastic polyolefin, membrane. TPO is said to combine attributes of EPDM and PVC while qualifying as a "green" product.

The foundation is spread footings and isolated footings.

Westin Beale Street Hotel, Memphis. Building a hotel for visiting NBA teams is like building other hotels, with one exception. You have to raise the doors, the room ceilings and showerheads by 1 ft.

That is how Flintco Inc. of Memphis is handling the top floor of the $22 million Westin Beale Street Hotel, across from the Fedex Arena in Memphis, home of the Memphis Grizzlies, said Danny Moeschle, project manager. Rooms on lower floors in the 203-room hotel have regular dimensions.

The nine-story building has post-tensioned concrete slabs, held with 121,000 lbs. of steel cable. Another 650 tons of rebar and 7,700 cu. yds. of concrete are going into the building.

The exterior includes a "signature" glass curtain wall that slopes inward on one corner, along with brick veneer and EIFS, he said.