A manufacturing facility in Illinois specializing in the production of ice cream, frozen desserts, baking products, cereal, confections, and other snacks had a section of freezer floor damaged by forklifts and personnel moving inventory in temperatures that reach -20°F. While these low temperatures present challenges for the proper curing of concrete, Structural Preservation Systems devised a repair solution to protect the concrete from freezing during the curing process.
Tenting the area around the repair to raise temperature levels was insufficient because it would not address a sudden freeze by contacting the subzero concrete around the perimeter and the inevitable development of condensation on the tenting material. Because of the facility's inventory, raising the entire freezer temperature was not an option.
Structural Preservation Systems designed a unique repair solution using a hydronic radiant heating system that utilizes warm water tubes embedded or attached to a floor to provide warmth.
The deterfiorated concrete was removed and holes were doweled for installation of new reinforcing steel. The hydronic heating system consisted of Pex Al Pex (plastic aluminum plastic) tubing attached to a welded-wire mat. The configuration of the tubing was designed to maximize heat distribution throughout the repair area and to avoid hot and cold spots. The tubing was fed into an electric water heater, and then into the repair area using two in-line pumps for circulation of the 150°F heating liquid. Around the perimeter of the repair area, insulation board was installed to isolate and protect against freezing of the new concrete. After the concrete was placed, the repair area was covered with heat blankets and insulation to ensure proper curing at the surface.
After proper curing of the repair area, the insulation board around the perimeter was removed and replaced with a chemical mortar used to anchor fastenings in concrete where the temperature is below freezing. The heating system was then removed and the tubing, still within the slab, was cut back and grouted shut.