Through the Roof
Through the RoofPutzmeister boom pumps extend over and above to place concrete through the roof into tight confines
STURTEVANT, WI (August 10, 2009) – To prevent construction costs from going through the roof when building three radiation vaults, two Putzmeister truck-mounted concrete boom pumps literally went through the roof of an existing building. Using their end hoses to extend down a small 12-inch (305mm) square opening, the boom pumps cost-effectively placed concrete within exceptionally tight confines.
The radiation vaults, utilized for treating cancer patients, were built in a fully finished one-story building located in the Palomino Park Professional Center – a complex with medical and non-medical office condominiums in the heart of Wellington, Florida near West Palm Beach.
The construction of the three vaults, relying on the concrete’s density to isolate radiation within one 20-foot (6.10m) square and two 25-foot (7.62m) square rooms, proved exceptionally challenging during concrete placement of the walls and roof. Beyond the uncommon access through the roof, crews were also faced with an incredibly confined work space, demanding continuous pours, extremely thick concrete walls and a speedy completion.
Anderson-Moore Construction Corporation (AMC) of Lake Park, Florida served as the general contractor and selected Sun Deck Concrete, Inc. (Sun Deck) of Riviera Beach, Florida, as the concrete contractor. Working long hours, seven days a week, Sun Deck crews handled the intricate complexities and aggressive deadline required for the concrete work.
Basically, starting from scratch, the multifaceted project entailed constructing three new buildings within an existing building, further complicated by a narrow six-foot (1.83m) wide and short seven-foot (2.13m) tall doorway as the only entrance inside. As larger construction machines could not enter the undersized doorway to assist, crews manually saw cut 4,000 square feet (372m²) of concrete and excavated 24 inches (610mm) of dirt for removal from the facility. Then, they hand carried and placed 100 tons of rebar indoors in preparation for the concrete.
Once a new two-foot (0.61m) thick concrete foundation was in place, Sun Deck called upon the 16 years concrete pumping experience and technically-advanced equipment of M&M Concrete Pumping, Inc. (M&M) of Pompano Beach, Florida, to pump 900 cubic yards (688m³) of concrete for the difficult-to-access walls and roof. These areas would challenge M&M’s ingenuity and their equipment’s reach and pumping capabilities needed to complete the job with efficiency and reliability.
The lofty 12-foot (3.66m) high walls, which ranged from four-and-a-half feet to almost seven feet (1.37m to 2.13m) thick, required a continuous concrete flow to avoid cold joints and prevent radiation leaks. Various alternatives were sought to ensure a non-stop concrete placing process, yet avoid a highly labor-intensive approach. The unique solution proved to be using the end hose of a truck-mounted concrete boom pump to go through an existing air vent in the roof.
As a result, the versatility of long-reaching and smooth pumping concrete boom pumps were put to the test. M&M scheduled their Putzmeister 38Z-meter truck-mounted concrete boom pump with its 121-foot nine-inch (37.11m) vertical reach to effectively access the roof and the unit’s exclusive free flow hydraulic system to prevent boom bounce.
M&M additionally sourced a Putzmeister 36-meter boom pump at a 116-foot nine-inch (35.59m) vertical reach, also featuring smooth free flow hydraulics, from JJC Construction (JJC) in Boynton Beach, Florida. The two pumping companies, although competitors, regularly assist each other with the same manufacturer’s brand of equipment to better serve their individual clientele.
To setup, the boom pumps deployed their compact outriggers next to the building, extended their booms to the rooftop and each maneuvered their end hoses through a separate 12-inch (305mm) square opening in the roof. At this point, each end hose was connected to a 90-degree elbow and reducer, then 20 feet (6.10m) of four-inch (100mm) delivery line from one end hose, and 40 feet (12.19m) of delivery line from the other end hose.
The delivery line looped 20 feet (6.10m) around one vault’s perimeter to pour a three-foot (0.91m) lift of concrete at a time. The other 40-foot (12.20m) delivery line handled the other two vaults, again pouring concrete in three-foot (0.91m) lifts to complete the walls within four passes.
“We were going around in circles with the delivery line, making sure the concrete didn’t get hard before we got back to the starting point to make another go around,” notes Mark David, Sun Deck owner/president. “It took about 45 cubic yards (34m³) of concrete for every foot of wall poured.”
“Precise placement of the boom tips was especially critical through the two small openings in the roof,” says Mike Moberg, owner of M&M. “Once the booms were positioned, the boom pumps’ smooth free flow hydraulic system kept the boom tips from surging or bouncing around so we didn’t damage the roof.”
Conscious about Cold Joints
Throughout the pour, everyone was especially conscious about preventing cold joints for the leak-proof vaults. Inside the building, the pumps’ operators stood on a special elevated platform between the walls, diligently taking their cues to maintain a smooth, consistent concrete flow. Outside, ready mix trucks were continually dispatched from Cemex’s batch plant in Wellington, Florida, supplying a three-quarter inch (0.75mm) blend mix with smaller stone and special additives without delay.
A trailer-mounted concrete pump provided backup at the job site; however, it was not needed as the boom pumps performed without interruption, placing 600 cubic yards (459m³) of concrete at a steady volume. The non-stop performance by man and machine finished the tall, thick walls in eight hours.
On Hands and Knees
Later when the three-foot (0.91m) thick vault roofs needed concrete, M&M’s modern 38Z-meter teamed up with their high performance Thom-Katt® TK 70 trailer-mounted concrete pump to place 300 cubic yards (229m³) of the special mix.
Again, the boom pump extended its end hose through the small opening in the roof to pump concrete, while the trailer pump placed the mix through 150 feet (45.72m) of delivery line that snaked through a small doorway. The 101-horsepower (75kW) trailer pump, capable of outputs up to 74 cubic yards an hour (57m³/hr) and high pressures up to 1,130 psi (78 bar), had plenty of power to assist.
“Concrete work for the vaults’ roofs was extremely difficult because of the tight space constraints,” says Moberg. “Workers crawled on their hands and knees when placing the concrete because there was only 30 inches (762mm) of space between the metal rafters of the existing building and the new rooftops.”
“It was such a small, cramped area that I initially wondered how in the world this would work,” adds Moberg, “but the crew and equipment did an incredible job.”
“Later, a two-foot (0.61m) thick concrete overlay was added in the center area of each rooftop as extra insurance in avoiding leaks, consuming 25 cubic yards (19m³) of concrete,” says David. “Overall everything worked out great, and we finished the entire project in only 35 days.”
“Going through the roof using a boom pump’s end hose combined with the extraordinarily tight 30-inch (762mm) height allowance is what made this project unique; however, there were other ironic twists associated with this job,” says Jim Henegar, co-owner of Miami, Florida-based Thomas Concrete Machinery, Inc., the authorized Putzmeister distributor. “Oddly enough, JJC’s 36-meter boom pump working at the job site was previously owned by Sun Deck, the project’s concrete contractor.”
Sun Deck owned the 11-year-old 36-meter boom pump prior to it being traded in at Putzmeister’s Pro-Tech Certified Used Equipment center in Sturtevant, Wisconsin. There it received the “Fully Refurbished” level of service, including new wear parts, boom, hopper, flatpack, and truck evaluation and repairs, prep and paint and a 119-point DOT used truck inspection. The fully reconditioned machine returned to southern Florida, but to a new owner, ironically JJC. With a factory-certified refurbishment, the unit was ready for years of additional operation.
“No one can believe the pump is a model year 1998, as it looks brand new and works great,” says John Churey, owner of JJC and the refurbished boom pump. “Putzmeister’s Pro-Tech facility did an outstanding job.”
Noting yet another ironic spin, Henegar says, “The reconditioned pump had been revitalized to extend its operational life, and then performed reliably on the radiation vault project; which, ironically has a similar goal of revitalizing cancer patients to extend their lives. Now, that’s a positive twist, as both man and machine are given a second chance.”