Rising 850 feet above downtown Oklahoma City, Okla., is the Devon World Headquarters Tower, which is expected to be the tallest building in the state once complete. An impressive lineup of Putzmeister America, Inc. equipment pumped and placed an estimated 120,000 cubic yards of concrete for the 1.7 million square foot structure.
Part of the city's "Core to Shore" downtown redevelopment project, which aims to redevelop 750 acres of underutilized land between the core of downtown to the shore of the Oklahoma River, the building will be the new headquarters for Devon World Headquarters, LLC, a subsidiary of Devon Energy Corporation and the largest U.S.-based independent oil and natural gas producer.
The building will comprise a 130-foot tall metal and glass rotunda, a five-story podium building and a 10-story above- and below-grade parking garage.
An aggressive pour schedule, a unique mix design and extreme weather conditions (hot, cold and windy) spurred Miami-based C&C Concrete Pumping, Inc. (C&C), the concrete pump and placement sub-contractor on the project, to enlist their trusted Putzmeister equipment to get the job done on time and on budget.
"24 floors of the building needed to be occupied by the end of 2011 and the remaining 26 floors by summer 2012," explains Laszlo Fazekas, National Marketing Director of C&C. "Consequently, a high-early concrete mix was specified to meet this demanding pumping schedule and to also combat the freezing weather conditions and reduce finishers overtime. Due to these circumstances it meant we needed to supply the most efficient and dependable concrete pumping and placing equipment.
"From our experience of completing 100-story plus high-rise buildings with our Putzmeister equipment, we knew it would pump the concrete mix design under extreme pressures in the most efficient manner possible," says Fazekas.
Arriving on site in April 2010 C&C enlisted one MX 34/38Z placing boom with lattice tower, two BSA 14000 HP-D 8-inch trailer pumps and one Thom-Katt TK 50 high pressure shotcrete/concrete pump.
"The two trailer pumps were set up side by side," explains Pepi Cancio President of C&C. "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, except this time the cross-base was bolted to a newly poured concrete deck in the roof as 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-pound, 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.
According to Fazekas, a 24-hour pour schedule to place the 120,000 cubic yards of concrete was implemented from the time the equipment was initially set up until the top off of the structure.
"The horizontal element pours were done at night while the vertical elements were done during the day," says Fazekas.
"There were three slab pours per typical floor," adds Cancio.
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 averaged outputs from 50 to 90 cubic yards per hour.