Separate Placing Boom Has Key Role in Performing Arts Center
Developing a concrete pumping plan is like casting a play with key performers chosen for their ability to fill a role. For the Dr. Phillips Performing Arts Center under construction in Orlando, FL, tight site access required a versatile method to deliver the concrete up and out with pump placement hundreds of feet from the pour locations. There was only one practical solution according to Project Superintendent Joe Brown, “We erected a separate placing boom in the orchestra pit.”
Dr. Phillip Phillips, a central Florida citrus magnate and patron of the arts, is the namesake for the $385 million project that is being built with public and private funds. Originally approved in 2007, the financing plan was scuttled due to the recession. The project has now been divided into two phases with groundbreaking occurring in June of 2011. The main features of Phase One are a 2,800 seat theatre for large scale performances and a more intimate 300 seat venue for local productions.
“The large theatre is like a big box with shear walls rising to 120-feet,” according to Brown, who is with Balfour Beatty Construction, managers for the project, operating out of their Orlando office. Brown chose Cross Enterpises’ Orlando operation to provide the pumping services for the 27,000 yards of concrete consumed on the project. “I am an Orlando native, “ Brown notes, “And I first worked with Cross at the Orlando Airport project in 1987 so I am familiar with their considerable pumping experience.”
Prior to below-grade structural concrete placement on the site, more than 700 augered cast-in-place piles were installed as deep as 85-feet to stabilize the Florida soil. HJ Foundations, Orlando provided the specialized service and used Schwing concrete pumps to fill the drilled piles under contract to Balfour Beatty. These cast augered piles were supplemented by 800 ram aggregate piers that are formed by layers of crushed rock hydraulically compacted in 12-inch lifts.
The high visibility location, directly across from City Hall, required a concrete placement plan that would minimize impact on the surrounding area. “Boom trucks would have caused lane closures, costly nighttime pours and complaints, “ according to Brown, “The exception to that plan were two slabs – a 560-yard lower mat and a 2100 yard upper mat that were pumped with three Schwing boom trucks. “
The larger slab incorporated an excessive amount of electrical conduit that required precision placement by the S 61 SX, KVM 52 and S 45 SX Schwing pumps. “Because this is an entertainment complex, the conduit was very dense requiring slow going to consolidate the mix around the utilities, “ explains Simon Villari, Cross operations manager, “Further complicating the pour was that the plan called for three separate mixes to be pumped.” The plasticized mixes – a base, pea gravel and pure cement – were poured over a 10-hour period. All of Cross’ boom pumps are equipped with Rock Valves. The pressure and forces inside the Rock Valve ensures the cutting ring keeps a tight seal, enabling the Rock Valve to handle such a wide range of mix designs
Another boom pump, playing multiple roles on the project was Cross’ Schwing KVM 39X with detachable boom. With horizontal reach of 114’10”, the boom can perform concrete placement of the shear walls and decks from one location. It is easily detached from the truck chassis with a four pin quick connect system and hoisted to the top of a tower. The Roll and Fold design allows precise placement from full reach to the base of the tower. The proportional boom controls were especially handy for the placement of the shear walls on the project. The operator maneuvers the boom from a vantage point on the top of the lattice tower next to the boom’s pedestal. Radio communication with the pump operator controls the flow of concrete.
“We mounted the lattice tower on a ballasted cross frame and positioned it in the orchestra pit, “ according to Brown, “We will add 14-foot sections to the tower as the shear walls reach their maximum height.” The base of the Liebherr tower is located 18-feet below grade with the placing boom at 55-feet. Three more tower sections will be added to raise the boom to 97-feet ultimately. Dewey Harding, concrete manager for Balfour Beatty, commented on raising the tower, “The picking weight of the boom allows us to remove it from the tower with the on-site crane. We then add a section of lattice and reset the four pin quick-connect system of the boom’s pedestal in about an hour. It is a team effort with the Cross crew.”
The truck chassis with pump is located 150-feet from the separate placing boom and tower. The two-block area has been cleared for Phase Two construction allowing truck mixer access to the northern boundary of the site. Five-inch pipeline has been installed between the Schwing truck pump and a thrust block at the base of the separate placing boom’s tower.
With the shear walls varying from 12 to 24-inches thick and incorporating double mats of #9 rebar, the contractors are pumping self consolidating concrete into the aluminum forms. A 3-inch tremie pipe is being fed by the placing boom’s five-inch boom pipe through a reducer. “We were experiencing some splatter inside the form when we couldn’t get the end hose deep enough because of the dense reinforcement, “ explained Harding, “So we switched to the tremie and it is working well.” The mix is a proprietary architectural concrete formula with super plasticizer batched and delivered by Cemex.
The walls are being constructed in 15-foot lifts and 100 to 150-foot lengths resulting in 95 to 120-yard pours. The 2023-5 Schwing pump kit with nine-inch diameter material cylinders and 79-inch stroke offers infinitely variable output up to 208 yards per hour and 1007 psi on the concrete. “We appreciate the smooth stroking of the Schwing pumps, “ adds Harding, “It makes the placing very efficient and we are on an aggressive construction schedule.”
Separate placing booms have become a popular tool in the Cross Enterprises’ repertoire. “We have two separate placing booms mounted on tubular masts going up on the Four Seasons Hotel on Disney’s property and a third job starting in Ann Arbor, MI out of our Detroit office, “ according to Orlando manager Peggy Cross, “Three separate placing boom projects at one time is a first for our company and, hopefully, a sign of better times ahead.”
Owner: Dr. Phillips Center for the Performing Arts, Orlando
Construction Managers: Balfour Beatty, Orlando
Pumping Contractor: Cross Enterprises of Florida, Orlando
Pumping Equipment: Schwing truck-mounted concrete pumps with placing booms – S 61 SX, KVM 52, S 45 SX and KVM 39X with detachable placing boom.