Essex on the Park Adds to Chicago Skyline
At 602-feet tall, the new Essex on the Park residential tower in downtown Chicago will fill a gap in the City’s skyline formerly occupied by a parking garage. Adjustable Forms, the 88-year old concrete structures contractor, based in Lombard, IL, is adding another notable high rise to their resume using state-of-the-art pre-planning and the latest in concrete pumping equipment. “ We utilize the latest equipment and technology to streamline many of our business operations, from estimating to construction including working with the general contractor, managing subcontractors and communicating with field staff,” according to Eric Lindquist, Adjustable’s president. The company credits the information obtained through thorough pre-planning and reliance on the most effective concrete pumping equipment as keys to improving their competitive position.
After demolition of the old low-rise parking structure at 800 S. Michigan Avenue in early 2017, the company poured the foundation for the new structure in early June. Very little excavation was required as the foundation sits just six-feet below grade. “The 1,500 cubic yard mat included a base for the tower crane, “ states Tim Saunders, general superintendent, Cast-in-place pumping began with the construction of five levels of parking and a sixth amenity level for the planned 479-luxury apartment units.
The pump and placing boom combination chosen for the Essex Park project is a new Schwing SP 9500 stationary pump and SPB 35 separate placing boom. The new high pressure pump with model designation 2018-7 150/90 offers up to 118 cubic yards per hour output and can apply as much as 3254 psi on the concrete in the two reciprocating material cylinders. Concrete transitions from the eight inch material cylinders through the High Pressure Rock Valve to a six inch outlet and into five-inch pipeline. “The 9500 has plenty of muscle,” according to Saunders. He credits the slow-stroking pump – just 30 strokes per minute – for the steady, smooth flow of concrete.
A notable feature that contributes to highrise pumping on the new Schwing is Symmetrical Switching. In practice the new refinement allows the water box end of the differential cylinders to feed oil evenly into the bridge hose at both switch points. Equal pressure generates symmetrical switching of the complete pump kit. The high hydraulic pressure of the pushing cylinder generates the switching signal with resulting equal switching of the Rock Valve for faster switching and continuous concrete flow. “While Symmetrical Switching is great for everyday pumping, the benefits are greater when pumping stiff mixes that generate higher concrete pressures, particularly when pumping high-rise buildings like the Essex on the Park structure,” according to Tom O’Malley, Schwing senior vice-president of sales and marketing. The new feature is standard on all high pressure stationary pumps and Schwing boom pumps. “We have noticed a reduction in pipeline movement and boom bounce,” notes Derek Wienkes, equipment manager for Adjustable, “There is also a reduction in the sound level which is always appreciated in an urban setting.”
As a sustainable leader in the construction industry, Adjustable insisted the SP 9500 be equipped with a Tier 4 630 hp Caterpillar diesel. “In addition to the improved emissions performance it is very easy to service the CAT power plant,” says Wienkes. At top-out later this year, the pump will be pushing the concrete more than 820-feet from its stationary position on the street to its 620-foot height. Mix designs vary from 12,000-8,000 psi for core and vertical mixes to 8,750 psi for deck mixes.
Adjustable’s placing team is using the Schwing separate placing boom to distribute the concrete on the vertical supports and decks. The placing boom is mounted on an X-frame bolted to the central core climbing form system. With 113’ 10” of horizontal reach, the four-section Roll and Fold™ boom is able to cover the entire 10,000 square feet of a typical floor from its elevated position. An electrically powered hydraulic powerpack is integral to the placing boom with proportional radio remote control. The core stays two stories ahead of the columns and decks. This configuration has been in place since June proceeding at the rate of one floor every three days. “Each floor requires almost 500 cubic yards including the core, “ explains Saunders, “We pour the deck, then form up the verticals and average 80-100 yards per hour at the end hose.” More than 26,000 cubic yards will be placed with this method resulting in more than 460,000 square feet of rentable space. The rapid pace is expected to top out the structure later in 2018. Completion of the $174 million tower is expected in 2019.
Construction on the skyscraper will coincide with a revamp of the neighboring 14-story Essex Inn building at 800 S. Michigan. The old hotel will connect to the new tower and see its room count expanded from 254 to 271. The midcentury structure will eventually share amenities such as a restaurant, elevated bar, and an indoor winter garden with its new residential neighbor. With the renovation the total cost of the two building project is estimated at $240 million.
Adjustable Forms continues to be the leading builder of concrete structures in the Chicago area. According to CEO, Jim Lindquist, “We can exceed expectations of our clients’ on even the most complex concrete frames. Our team offers the expertise and commitment to meet the requirements of any project. Adjustable Forms utilizes a collaborative approach with both designers, manufacturers and contractors to successfully build some of the most challenging concrete frames.”
Owner: Oxford Capital, Chicago
General Contractor: Power Construction Co. LLC, Chicago
Architect: Hartshorne Plunkard Ltd, Chicago
Concrete Contractor: Adjustable Forms Inc. , Chicago
Concrete Pumping Equipment: Schwing SP 9500 high pressure stationary concrete pump, Schwing SPB 35 separate placing boom.