Keep Out the Noise
Keep Out the NoiseOn Saturday, June 1, 2002, the elevated concrete pour for the entire Exhibit Hall roof of the Georgia International Convention Center (GICC) was successfully completed. As the structure's design required twenty times the normal amount of concrete for a mezzanine slab, it was not a typical roof-deck pour. The design's purpose was to fully insulate the roof with very thick concrete and keep out noise from the neighboring airport.
The 11-hour pour began at 2:00 a.m. and was completed by 1:00 p.m. From a structural standpoint, a continuous pour was necessary to give an equal weight distribution across the super-trusses. Upon completion, over 2,570 yards of concrete covered the unusually large 165,000-square-foot roof.
The general contractor for the GICC was Holder Construction Company of Atlanta. Mike O'Conner, the superintendent who orchestrated the challenging project, said, "Figuring the amount of deflection and preplanning the assembly of the super-trusses was a significant undertaking. Relying on the teamwork of all the sub-contractors was also a critical factor."
Air traffic restricts height
A convention center near the airport offers added convenience for trade show attendees. However, the same airport proved to be inconvenient for construction. As the convention center was located directly below the airport's flight path, construction equipment was restricted from reaching above 80 feet.
Therefore, Pumpco, Inc. of Forest Park, Ga., precisely choreographed the placement of their three 52Z-Meter and one 55-Meter Putzmeister pumps around the 50-foot-high roof's perimeter being careful not to exceed the air traffic height restrictions. The use of the Multi-Z boom proved especially advantageous because it allowed the units to set up in close proximity to the building and conveniently unfold while adhering to the maximum 80-foot height parameter.
Each pump also had 400 feet of 4-inch delivery line, which made a total of 1,600 feet of system. A backup 52Z-Meter Putzmeister pump was also on site but was not needed.
Mike Clark, a salesman for Pumpco, said, "The performance of the pumping equipment exceeded everyone's expectations, and the intense communication, organization and planning for four months really paid off. It was a complex job, but that's why we were hired."
Had to keep slump wet
Allied Ready-Mix of Atlanta supplied the commercial 3,000-psi concrete mix. A 6- to 8-inch slump was specified, and Allied realized that keeping the slump wet enough was a key factor in successful placement.
Mike Legrand, manager of field services for Allied, said, "It's not every day that you do a 2,500-yard roof deck. So it was a huge coordination effort between our company's four batch plants and 54 mixer trucks to continuously supply the concrete and maintain the required 250 yards an hour needed on this project."
The necessary output requirements were indeed met. This was due in part to the computerized batch systems Allied had in place, which loads its trucks faster. It was also due to the high outputs achieved by the Putzmeister .16H pump cells, which are capable of up to 210 cubic yards an hour.
Over 80 finishers on site
Because of the pitched roof, the grade had to be established using the dipstick method. Owner Paul Copoulos of Level Concrete in Atlanta had over 80 finishers on site to place and finish. They did all the work by hand as only a rough finish was needed and it kept the weight of laser screeds off the new roof.
Andy Hyde, superintendent for Holder, summed it all up by saying, "Everyone was a bit nervous because of the job's critical conditions. We had one shot to get it right - the team had to keep up a fast pace and the equipment had to perform flawlessly." Hyde also noted that there were no injuries, a critical factor when dealing with a construction job of this magnitude.
The 450,000-square-foot convention center located on 50 acres on Main Street in College Park is scheduled for completion in May 2003. Construction costs will run approximately $65 million.
Owner: Georgia International Convention Center - College Park, Ga.
General contractor: Holder Construction Company - Atlanta
Pumping contractor: Pumpco, Inc. - Forest Park, Ga.
Ready-mix supplier: Allied Ready-Mix - Atlanta
Finishing contractor: Level Concrete - Atlanta
Equipment: One Putzmeister 55-Meter and four Putzmeister 52Z-Meter truck-mounted concrete boom pumps