When Eaton Steel Corp., Taylor, Mich., decided to modernize existing warehouse storage, the company needed a heavy-duty superflat concrete floor with no transverse joints and minimal cracking. Transverse joints were undesirable because they would create bumps in the wheel paths of the warehouse's high-reach forklift traffic. And over time, joint spalling could hinder lift-truck efficiency and require extra maintenance.
The project involved the removal of existing concrete flooring and the construction of two 85x231-foot bays (more than 39,000 square feet). Because subgrade soil conditions were poor and the owner wanted joint-free lift-truck aisles, the design-build contractor designed a 16-inch-thick continuously reinforced concrete floor, locating all construction joints under the designated storage rack locations and eliminating transverse contraction joints. Specifications for the defined-traffic floor called for an Fmin 100 wheel-track tolerance. Because the slab was so thick, it required two layers of rebar—continuous in both longitudinal and transverse directions—to minimize cracking.
After removing the existing floor, crews placed the new floor in 12 alternating strips—each 240 feet long by 14 feet, 2 inches wide—on top of a subbase of 4 inches of crushed, well-compacted limestone. By taking special measures to ensure proper setup of the side forms and by using laser levels to continuously check and adjust form elevation during concrete placement and screeding, workers were able to exceed floor flatness specifications, achieving numbers averaging Fmin 105-115.