By fast-tracking precasting and erection operations, Forest City Dillon Precast Systems was able to complete the building frame for the Chilicothe Correctional Institution Number 2 in Ohio in about 8 months. Except for foundations and interior partitions, all of the building elements for the 19 two-story buildings were precast, including columns, beams, floor slabs, double-T roof slabs and exterior wall panels.
PRECASTING THE WALL PANELS
Wall panels were precast with polystyrene insulation sandwiched between inner and outer layers of concrete. The buff-colored outer layer of concrete was placed first, followed by a layer of polystyrene and the inner structural concrete layer. Recessed anchors for lifting the panels were installed in the outer structural concrete layer. Stainless steel ties were used to hold the two layers of concrete together.
ERECTING THE PANELS
Second-story wall panels were connected by coil rods to the floor slab and first-story wall panels. The coil rods were screwed into the bottom of a second-story wall panel after the panel was lifted a few feet off the ground. Then, as the panel was lowered into place, the coil rods were passed through holes in the floor slab and then into holes cast into the top of the first-story wall panel. These holes were filled with grout just before the second-story panel was installed. Supported by temporary braces, adjoining wall panels were connected by welding together steel plates embedded in the edges of the panels.