No Cold Joints November 2002
Cold joints aren’t desired when ice-skating and they’re not wanted in concrete construction either. So when pumping an ice skating rink, they’re especially undesirable.
Preventing cold joints was an absolute must when pumping “a super flat slab” to develop a National Hockey League-size ice rink inside the Parks at Arlington Mall in Texas. Only a 1/16-inch flatness tolerance was allowed throughout the entire 80-foot by 240-foot oval ice rink.
Because of the low ceiling heights inside the mall, a boom pump or conveyor was not feasible to pump the job. Therefore, a trailer-mounted concrete pump was the logical choice. Pumphaus.com, LLP of Dallas used its Putzmeister TK 70 Thom-Katt® to handle the project.
Because non-stop pumping was so important, Pumphaus.com was required by contract to provide a backup pump on site in case of equipment malfunctions. However, because of the reliability of the equipment, this pump wasn’t needed.
Workday started at 3 a.m. A total of 240 cubic yards of concrete were placed, starting at 3 a.m. and finishing up about five hours later. The early morning start was to ensure the availability and consistency of the mix from only one ready-mix supplier who could continuously provide concrete. Never missing a beat, 22 mixer truck loads of the 6-1/2 sack, 4000# pea gravel mix was supplied by Hanson Concrete of Dallas.
The general contractor, CIMCO Lewis Refrigeration of Houston, prepared the rink’s foundation in layers. From the bottom up, the cooling system consisted of a structural slab with a sand base. Then 2-inch Styrofoam and heat pipes were placed in the sand layer. Poly, steel mesh, cool pipes and then more steel mesh followed on the upper layers.
The piping had pressurized water running through it to check for leaks during the pour. It would be drained and filled with a special chemical used to cool the ice afterwards. A 5-inch concrete slab was pumped, which covered the heat pipes in the sand layer all the way up to the steel mesh topping.
Thom-Katt placed near end of rink To handle the continuous pour, the Thom-Katt was positioned near the far end of the rink. This allowed access for ready-mix trucks to discharge from the building’s 15-foot-tall by 20-foot-wide bay opening.
Coming off the trailer pump’s outlet was a steel 5-inch to 4-inch reducing elbow that led into 4 feet of boom hose to the ground for added flexibility. This went into steel line that stretched 80 feet to the center of the rink. A 90-degree elbow was then connected at that point, and an additional 100 feet of steel line was then placed. Then, 60 feet of hose was connected. This enabled the convenient placement of concrete from either side of the 80-foot wide rink.
Hard Rock Concrete of San Antonio, experienced with constructing ice rinks, was the finishing contractor with about 30 finishers and six power trowels on site. All this labor and equipment was needed to keep up with the Thom-Katt, which ran at almost maximum output by delivering over 60 yards an hour.
It was vital that nothing would touch the delicate cooling system underneath while pouring. Therefore, Pumphaus.com’s biggest challenge was keeping the delivery line steady while suspended 12 inches off the top steel layer. Through the use of A-frame sawhorses with chains, the pipe was suspended above the mesh while the hoses were placed in hose dishes to ease their movement across the steel mesh and cooling pipes.
Sawhorse placed on plywood The sawhorses also were placed atop 4-foot by 8-foot sheets of plywood, which helped spread the overall weight over a larger area of 32 square feet to help avoid any damage to the cooling system.
As setup was very crucial, Ed Sinayi, owner of Pumphaus.com said, “It was a bit nerve racking, as we had to be extremely careful not to damage the plastic pipes full of pressurized water. It would have stopped the pour and that would have been disastrous.”
Ice at the Parks, the NHL-size rink, is anticipated to be open virtually around the clock, with team practices and games booked late at night and early in the morning. The rink, which offers open skating and instruction, has two small sections of stadium-style seating for spectators. It is operated by Rink Management Services.
Along with ice at the Parks, the mall has expanded to include several retailers that are new to the area, two new parking decks, and an AMC 18-movie theater. The $65 million expansion was completed in November 2002.
JOB SPECS: Owner: Parks of Arlington Mall – Arlington, TX Finishing contractor: Hard Rock Concrete – San Antonio Pumping contractor: Pumphaus.com, LLP – Dallas Ready-mix supplier: Hanson Concrete – Dallas Equipment: Thom-Katt TK 70