The robots did the heavy work, but a 25-member crew from Raffin Construction Co. followed behind to get the concrete slab at the H-F Ice Arena in perfect condition.
The park district is using a new system recommended by American Arena. It layers a heating system covered by sand, then the cooling system is laid on top and covered by sand. That is topped with Styrofoam insulation. Rebar was screwed into the Styrofoam to make certain the cooling pipes didn’t shift when the concrete layer was poured.
In the Olympic-size rink, there are 12 miles of cold piping. The Studio Rink has the same pipe-layering operation.
On Oct. 12 starting around 7:30 a.m. the Ozinga Concrete trucks were lined up along Kedzie Avenue waiting to deliver 250 yards of concrete that would cover the heating and cooling pipes in the rink floor, a space that’s 200 feet long and 85 feet wide.
The concrete was delivered into the ice arena through pipes tethered to the trucks at one end and robots at the other. The robots take commands from the Raffin crew who direct where the concrete should be poured. The effort is coordinated with laser precision – literally. Lasers on a tripod at the perimeter of the rink are read by a screed, a driven machine with a smoothing blade. The laser on the screed, reading measurements from the tripod, help pinpoint how level the finish is.
“They take the blades at a wider pitch – that brings the crème to the top of the concrete and also knocks the aggregate down,” explained Pete Pietrusiewicz, superintendent for WB Olson, the general contractor on the job. The process also levels the top.
“After the first go-through, then (the screed) does what’s called panning. The panning is no blades but a pan on the bottom and that roughs the concrete finish and allows the moisture to come up,” he said.
The spouts on the little concrete machines were draped by white plastic helping to control the placement of the concrete. The machines moved back and forth across the surface covering the Styrofoam and rebar. Along the perimeter of the rink, crews worked to smooth the concrete and knock away concrete from the markers indicating where the dasher boards will be installed.
The process went on for hours with about 70 yards of concrete poured each hour. Crews were on the lookout for puddling and bubbling, Pietrusiewicz said.
The process was repeated the following day in the Studio Rink with 50 yards of concrete.
Once the concrete was deemed smooth, the job was completed by laying plastic over it.
A time-lapsed video is on the Homewood-Flossmoor Park District website.
Right now, the floor is curing. The process is expected to take 28 days to get the concrete between 5,000 and 7,000 PSI in strength. To help the curing process along, a fine water mist is sprayed on it for 14 days. That will help the concrete maintain adequate moisture.
After 14 days, a sealant will be applied to the concrete. Then the concrete will settle another 14 days.
In mid-November, the rink will have been shut down for one year. Park commissioners are aware of the interest in the work, and residents ask questions of why it takes so long, said Commissioner Steve Johnson. The park board worked as quickly as possible, he said.
There have been several supply chain delays and a strike at the quarry affected construction of the building that will house the mechanicals. But overall the work has gone smoothly, said Pietrusiewicz.