EnergetIc placement

Dolese Bros. delivers 120,000 yd. to tallest 2010–2011 building project west of the Hudson River

Rising 850 ft. above downtown Oklahoma City is the Devon World Headquarters Tower, Oklahoma’s tallest building upon a summer 2011 top out. The project is an ambitious component of the city’s “Core to Shore” redevelopment project, centered on 750 acres of underutilized land between downtown and the Oklahoma River.

The new home for Devon World Headquarters, LLC, a subsidiary of Devon Energy Corp. and the largest U.S.-based independent oil and natural gas producer, will comprise a 130-ft.-tall metal and glass rotunda, five-story podium building, and 10-level above- and below-grade parking garage.

Armed with a lineup of Putzmeister America equipment, Miami-based C&C Concrete Pumping Inc. pumped and placed upward of 120,000 yd. of high performance and conventional concrete for the 1.7 million-sq.-ft. building. Facing an aggressive pour schedule, unique mix designs and extreme weather conditions (hot, cold and windy), C&C crews owned up to their schedule and budget terms for the joint venture general contractor, Holder Construction, Atlanta, and Flintco LLC, Tulsa, Okla.

“Twenty four floors needed to be occupied by the end of 2011 and the remaining 26 floors by summer 2012,” explains C&C National Marketing Director Laszlo Fazekas. “Consequently, a high-early concrete mix was specified to meet this demanding pumping schedule and to also combat the freezing weather conditions.

“From our experience of completing 100-story plus high-rise buildings, we knew [our equipment] would pump the concrete mix design under extreme pressures in the most efficient manner possible.”

Arriving on site in April 2010, C&C enlisted one MX 34/38Z placing boom with lattice tower, two BSA 14000 HP-D 8-in. trailer pumps and one Thom-Katt TK 50 high-pressure shotcrete/concrete pump. “The two trailer pumps were set up side by side,” explains C&C President Pepi Cancio. “One was utilized for pumping on site while the other was on stand by in the event extra support was needed.”

For most of the floor pours, the pedestal was bolted directly to a cross-base, which was mounted to the structure’s climbing core wall forming system. Once the climbing core wall forming system was removed, a 40-foot tower was mounted to the cross-base, in turn bolted to a newly poured concrete deck in the roof per the guidance of Putzmeister engineers. This method allowed one placing boom mounting system to be used as both a climbing and static mounting system.

“The placing boom and pedestal, with a combined total weight of 18,600 lbs., was flown to and from the tower with ease,” explains Cancio. “Positioning the boom on the pedestal also proved to be a simple process.”

While the trailer pump and placing boom were used for the horizontal flatwork and vertical elements, the TK 50 was used for miscellaneous concrete placement needs including stairs, pour backs and pop-ups.

Round the clock
According to Fazekas, a 24-hour pour schedule—with three slab pours per typical floor—was implemented from equipment set up to building top off. “The horizontal element pours were done at night,” he says, “the vertical elements during the day.”

High-pressure, low-output pumping was a necessity on this project due to the heights that had to be attained with a challenging concrete mix design. The BSA models averaged 50- to 90-yd./hour output. “[It] varied due to the density of the mix design and the weather,” explains Cancio. “The mix included superplasticizers to meet pumpability and workability requirements for concrete finishing, and dense aggregate to meet the strength demands.

“In the winter, this mix was more challenging to pump because the aggregates could not be maintained at Saturated Surface Dry condition due to freezing temperatures—when aggregates absorb lots of free water, leaving a somewhat sticky paste. Luckily, we were able to depend on powerful pumps and great concrete finishers to [place] the harsh, high strength mixes.”

With the BSAs’ closed-loop, free flow hydraulics, C&C was able to provide a smoother and more controllable pumping method in the varying weather conditions. “The pump has a fully adjustable volume control to allow for very slow pumping while retaining full concrete pressure of 3,190 psi, making the BSA ideal for this type of job,” adds Jovanny Cabral, General Manager for the C&C Dallas branch.

With a 54-yd./hour capacity at 1,150 psi, he adds, “the TK 50 features a gradual reduction from hard-chromed material cylinders to the outlet, providing an even flow of material, and ultimately providing us longer life of the pump.”

“We knew our equipment and experience would stand up to the grueling demands,” notes Cancio, crediting the project’s success to “a great combination of people to work with from the owner and developer and general contractor, to the ready mix concrete company.”   — Putzmeister America Inc., 800/884-7210; www.putzmeisteramerica.com