TRAFFIC CONTROL FACILITY POSES CONCRETE CONUNDRUMS
Since May 22, R.L. McCoy, Indianapolis, IN has been a regular player in the construction of a new ground traffic control tower and tracon at the Indianapolis Airport in Indiana. The effort is the lead project in a $1 billion new construction and renovation of the airport’s existing facilities. The first yard of pumped concrete went into the foundation for a new traffic control tower in early June. The tower is projected to become the second tallest of its kind in the United States. When concrete construction tops out at 286 feet, a four-story steel cab installed on top will bring the tower’s height to just under 400 feet. The adjoining tracon facility will measure 43,000 square feet and house equipment to monitor the Indianapolis area’s air traffic.
Indianapolis-based construction managers Hunt Construction Group and Smoot Construction, and ready-mix supplier Prairie Group, Indianapolis, are currently struggling to incorporate a total 1440 yards of white architectural concrete into the tower while McCoy completes perimeter wall and slab pours on the tracon. Concrete contractor Hagerman Construction Corporation, also from Indianapolis, is overseeing supply and placement of both structures through completion.
R. L. McCoy began pumping on May 22, placing the tower’s strip footings. On June 3, McCoy brought in two Schwing concrete pumps to pour the foundation, a giant slab measuring 55 feet by 55 feet by eight feet thick. The 890-cubic yard monolithic pour was completed with a 32 XL and a KVM 39 X. Each pump maintained strong production throughout the 7-hour pour, the 32-meter pumping out 420 yards while the 39-meter placed 470 yards of the 4,000 psi concrete.
Ready-mix supplier Prairie Group, operating from their Indianapolis plant, dispatched 25 trucks to supply the pumps with a specially designed mix. Prairie Quality Control Manager Kerry Webb and McCoy President Gary Brown said the mix design was particularly important considering the slabs’ thickness. To prevent structural cracking, the supplier used a 70% slag replacement method and low heat of hydration.
“With an 8-foot thick slab, all of that concrete produces heat and eventually cracks,” said R. L. McCoy President Gary Brown. “The engineers and suppliers did a great job selecting a slow-setting mix. Sticky stuff. It took fifty-six hours to get to maximum strength.”
With the foundation completed, contractors moved on to incorporating approximately 45 yards per level into the 30-level tower.
To help project managers stay on schedule with concrete construction, McCoy aided in placing the second floor of the tower, pumping approximately 45 yards of white architectural cement. McCoy President Gary Brown immediately recognized the inconsistencies between what had been placed via crane and bucket versus the concrete that had been pumped.
“The concrete was mixed with white coloring to create the look they wanted. When it was run through the pump, the agitation process made the mix a little more consistent in terms of coloration. With the crane and bucket method, the mix coming directly from the trucks was less consistent. The owners needed to either bucket the entire job or pump the entire job to maintain aesthetics. A crane was already on site, so I suggested they stick with how they started. I don’t often turn down pumping work, but it made the most sense for the owners and every one involved. Besides that, it was a 7500-pound mix consisting of mostly sand and stone – less than pump friendly.”
Randy Williams, Project Manager with general contractor Hunt Construction said the issues with the mix hasn’t hindered production or set them back, but has remained a constant challenge. “It’s been interesting. With the temperature fluctuating, the process constantly changing and environmental elements playing against us, the mix can come out any which way. We need to be as careful as possible with this stuff.”
As of late August, Prairie had supplied 300 yards of the white cement mix to the traffic control tower project.
While tower construction continues, R. L. McCoy and Prairie are plugging away on concrete construction of the adjoining tracon. The month of June was dedicated to pouring the footings, and individual pours ranged from 90 to 180 yards.
Prairie crews and McCoy operators have placed nearly half of the tracon’s 896 yards of concrete thus far. Since the beginning of July, several pumps from McCoy’s 16-pump fleet have been on site to complete several wall pours. “We’ve have everything from our twenty-eight meter to our forty-two meter on site,” said Brown.
Because of the size and depth of the excavation, McCoy has utilized longer booms to complete the wall pours. The pumper’s KVM 39 X has been on site for the majority.
“The excavation is huge. With a 35-foot cut back and some walls measuring nearly 80 feet long, we need the long boom. Plus, pump set up needs to happen at least eight to ten feet from the bank. With the outriggers we need as much space as possible to set up. And when we wrap around corners that 105-foot reach is absolutely necessary.”
R.L. McCoy, which began as a bridge building service in the 1960’s, owns two Schwing KVM 39 X pumps. Each has been customized to comply with strict Indiana bridge laws and equipped with extra axles, tandem steer and pusher.
Quality Control Manager Kerry Webb estimates that the combined efforts of Prairie and McCoy will supply the new tower and tracon project with a total 2400 cubic yards of concrete. Prairie has also been commissioned to complete some landscaping work surrounding the facility, including curbs and sidewalks.
The new facility is scheduled for operation in Spring 2004, and subcontracting work will continue to be let through fall 2003 and early winter 2004. Once the traffic control center is completed, the existing Indianapolis airport terminals will undergo major renovation.