Challenging Tower Block Structure - continued
Concrete was pumped by four of Pietrini’s 14 Schwing boom pumps to a thickness of 10-feet. The monolithic slab consumed more than 400-tons of reinforcing steel.
375 Truck Loads Delivered
The night pour began at 1:45 a.m. on a weekend to avoid traffic in the downtown location. The company’s Schwing S47 SX and S39 SX truck mounted pumps with placing booms were teamed with a pair of Schwing S34 X boom pumps to provide a continuous flow of concrete from more than 375 truck loads dispatched from two suppliers – SJA Concrete of Philadelphia, and Action Concrete Supply of Sharon Hill.
The B. Pietrini crew of 45 workers took 12 hours to complete the pour.
The building site leaves little room for a concrete pump and access for truck mixers. The Schwing SP8800 concrete pump purchased for the project is straddling the sheeting and angled into the site to keep truck mixers off the street.
The 2020-7 150/90 pump kit can place up to 152 cubic yards per hour when configured in the high volume mode and apply up to 2364 psi on the concrete in the high pressure mode.
A 500-horsepower diesel engine powers the unit that includes twin 190 hydraulic pumps, eight inch material cylinders, and the HP Rock Valve with dual shifting cylinders, ideal for high pressure applications and capable of handling the harshest mixes with up to 2.5” aggregates.
Changing Dimensions as Structure Rises
The concrete core preceded steel erection on the project. At ground level the core accommodates eight elevator banks. The core walls are four-feet thick at ground level and taper to two-feet thick at the top.
In a first for high-rise construction in the U.S., the crane used for constructing the core wall and slabs was attached directly to the concrete core walls.
As the crane moves up, a support structure is tied to the outside of the core.
The buildings bottom floors cover 40,000 square feet up to the sixth level, then taper down to 28,000 square feet up to the hotel level on the 48th floor.
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