To lift 2000-pound loads 45 feet high in narrow warehouse aisles, high-rise lifts or turret trucks weighing nearly 20,000 pounds require extremely flat floors. Construction specifications for IBM's 110,000- square-foot warehouse in Tucson, Arizona required the aisle floor to be level within 1/24 inch along an aisle that spans about 200 feet.
To meet these requirements, an 8-horsepower, gasoline-powered concrete grinder was used. The grinder was equipped with a 10-inch-diameter grinding head made of a circular metal plate with twenty diamond segments brazed onto it. The grinding head rotated at approximately 1000 revolutions per minute and was water cooled.
After the concrete had hardened, a profilograph measuring device was pulled over the surface and a readout of the floor's exact surface profile was produced. Based on this readout, areas out of level were ground, the slurry was removed and the floor was remeasured. To meet the specified tolerance, some areas had to be ground several times. The entire 110,000-square-foot floor required 100 hours of grinding, and between 1/16 and 1/8 inch of concrete was removed.