Tall Tower Changes NYC Skyline
Tall Tower Changes NYC Skyline
The New York City skyline will soon experience a dramatic change when Central Park Tower debuts as the tallest residential building in the Western Hemisphere. At 1,550 foot (472m) tall, the behemoth skyscraper is relying on standard Putzmeister concrete placing system to pump concrete to great heights, place a tough mix under high pressures, and help tackle a highly intricate project that will feature the most dramatic cantilever in Manhattan to date.
Upon completion in 2020, the 99-story skyscraper at 217 W 57th Street in Midtown will include ultra-luxury condominium residences and dynamic amenity spaces, as well as a 285,000-square-foot (26,477m²) Nordstrom department store. The new seven-story retail space will be Nordstrom’s flagship location in New York City, with the high rise often referred to as the Nordstrom Tower.
The tower is being developed by the Extell Development Company and SMI USA, and is slated to be the most expensive condo project in the city's history. Construction began in 2014, with concrete placing system installed in January 2016 by Pinnacle Industries II, LLC of Harrison, New York. The well-known contracting company, incorporated in 2001, had vast experience, but they needed the ideal combination of concrete placing system to perform the complexities of the colossal job. They looked to Putzmeister products sourced from the Paterson, New Jersey-based Alexander Wagner Company, Inc., authorized Putzmeister distributor for more than 30 years.
Standard Production Models
With key input from the manufacturer and distributor, Pinnacle ordered high performance concrete placing system capable of handling an anticipated 100,000 total cubic yards (76,455m³) of concrete for the high rise feat.
"Even with construction of one of the world's tallest skyscrapers, all concrete placing system ordered was standard equipment from the production floor — without any special modifications to alter performance," says Alex Wagner, Jr., co-owner of the Alexander Wagner Company.
Equipment included a BSA 14000-D HP 8" trailer pump, with eight-inch by 83-inch (200 x 2100mm) material cylinders. Currently at work at the Central Park tower, the trailer pump is proficiently providing the outputs desired. In early November 2017, the tower reached a 630 foot (192m) height, with the trailer pump competently attaining 84.5 cubic yards per hour (65m³/hr) volume at 1,450 psi (100 bar) pressures, from the rod side. This output was maintained while pumping 12,000-psi concrete, which has a much greater friction factor than the 6,000-psi concrete expected on the upper floors.
The trailer pump model will accommodate pours up to 1,200 foot (366m); however, at this height, the BSA 14000 HP-D4 7" trailer pump will step in, as it can achieve even higher pressures up to 3,350 psi (231 bar) and offer maximum outputs up to 74 yd³/hr (57m³/hr), on the piston side. Consequently, it could better meet the higher output objectives requested by the contractor for the upper floors. The initial trailer pump now being used will then go on standby.
The BSA 14000 HP-D4 7” trailer pump features seven-inch by 83-inch (180 x 2100mm) material cylinders and is equipped with a powerful 630 hp (470kW) Cat engine that meets the Tier 4 emission directive. When the manufacturer converted to Tier 4 engines, a full redesign of the new model was accomplished, so the unit provides even more power as well as reduced fuel consumption than the previous version.
Smooth and Steady
To precisely place the concrete, the Putzmeister MX 28/32Z separate placing boom was selected for its 78 foot (28m) horizontal reach that could access all areas without using additional hoses. Since this lightweight placing boom model had already been used on the brand of formwork chosen for the project, weight would not be an issue.
Other equipment needed for the project was the RS 750 pedestal and a clamp down base that is bolted to the formwork within the elevator core and allows the placing boom to climb with the forms. The RS 750, in this mounting configuration, offered more choices of where the concrete delivery pipeline could enter the pedestal — from either the side or the bottom, allowing greater flexibility on the job site.
Since the MX 28/32Z placing boom would be attached to the climbing formwork, keeping boom bounce to a minimum was very important. This was accomplished with the exclusive free flow hydraulic system that is standard on Putzmeister concrete pumps. Free flow hydraulics reduces changes in material pressure, ensuring smooth pumping and consistent concrete flow.
"Without free flow hydraulics, the trailer pump's output would need to be reduced below the hourly volume desired on the project, and maintaining output was a big concern in the initial planning meetings," notes Wagner.
Remarking on equipment performance, John Najarian, employed by Pinnacle for 19 years and presently the company's Executive Project Manager, says, "We've used Putzmeister products in the past and they've always been reliable; and so far, the equipment we ordered for this project has been performing as expected."
Further commenting on the distributor's role on the high-profile project, Najarian notes, "The Alexander Wagner Company is very knowledgeable about the equipment and has been attentive and dependable in their service and support."
The pipeline is five-inch (127mm) in diameter; and when used with the trailer pumps that have five-inch (127mm) outlets, a reducer is not needed. From the ground up, one-quarter-inch (6mm) heat-treated single wall pipe was used to place approximately 45,000 cubic yards (34,404m³) of concrete. At this point, the original pipeline was replaced, and two brand new pipelines installed to finish the job – both half-inch (12mm) heat-treated single wall – one for placing concrete, one on standby.
Strong Concrete Mix
A supertall skyscraper calls for a super strong concrete mix. For the bottom levels of the building, a tough 14,000-psi concrete was used. It changed to 12,000-psi when reaching about 500 foot (152m) heights. As the structure rises, the mixes will alter, resulting in 6,000 psi mixes anticipated for the upper floors. The ready mix company, Empire Transit Mix, consistently supplies the concrete from its Brooklyn location.
The tower was designed by Adrian Smith + Gordon Gill Architecture, the same firm behind the world’s current tallest tower, the Burj Khalifa at 2,717 feet (828m), which also relied on Putzmeister placing system for concrete placement.
Capitalizing on purchased air rights, Extell introduced a unique 30 foot (9m) cantilever over an existing property 300 foot (91m) above the ground elevation, which will offer future residents unprecedented views of Central Park. As it stands now, the cantilever is a self-supporting system consisting of 5,000 cubic yards of concrete (3,823m³) within a 36 foot (11m) tall outrigger/belt wall between the 12th and 13th floors, upon which 1,200 foot (366m) of the tower’s structure sits. Adding to its rigid stability are the main core walls and super columns that post up from the foundation. For concrete placement, the same trailer pump and placing boom combination was effectively utilized for this complicated construction endeavor.
Luxury at a Price
Numerous amenities will be found in the luxurious tower, which can also boast incredible Central Park and Manhattan skyline views. Speculation about condo prices runs rampant, with news sources claiming that 20 of the 179 condos will have a price tag of $60 million and above, while the most expensive listing contemplated to be $95 million.
Developer: Extell Development Company; and SMI USA, the U.S. subsidiary of Shanghai Municipal Investment — New York, New York
Architect: Adrian Smith + Gordon Gill Architecture LLP — Chicago and Beijing offices
General Contractor: Bovis Lend Lease — New York, New York
Concrete Contractor: Pinnacle Industries II, LLC — Harrison, New York
Ready Mix Supplier: Empire Transit Mix — Brooklyn, New York
Equipment Distributor: Alexander Wagner Company, Inc. — Paterson, New Jersey
Equipment: Putzmeister MX 28/32Z separate placing boom, Putzmeister BSA 14000 HP-D 8" trailer-mounted pump, Putzmeister BSA 14000 HP-D4 7" trailer-mounted pump, Putzmeister RS 750 pedestal and a Putzmeister clamp down base