Custom-made steel forms may be very expensive or very economical, depending on how many times they can be reused. When the reuse factor is good and a customized forming system provides other advantages such as better use of crane time, faster and more efficient placement of concrete and a minimum number of form ties, the relatively high first cost can become a bargain. The Stateville Correctional Center building in Joliet, Illinois, has eight equal-size wings that branch off a central axis on each of three floors. Among the 24 wings, however, there were four different floor plans, and this led to a form design based on the individual cell as the repetitive module. Hinging some of the form assemblies made it possible to keep them in one piece and yet permit easy stripping. Cell forms were rearranged from wing to wing to create the different floor plans.
To ease placement in thin walls heavily reinforced with wire mesh and electrical conduit, a thin, superplasticized concrete mix was used. Some of the concrete was pumped, but since a crane was on the job to move the wall forms, 75 percent of the concrete was placed by crane and bucket. When pumping, a half-wing was placed in 45 minutes. With a crane and bucket these 27 cubic yards of concrete were placed in about 90 minutes. Starting at one end of the half-wing and moving straight down the line to the other end, wall forms were filled to the top with concrete in a single pass. Placing the walls in a single lift saved moving scaffolding and laborers back and forth and thus saved valuable time, especially important when using superplasticized concrete.
The steel forming system cut finishing labor and cost by producing a smooth, as-cast finish with few joint lines. Overall performance of the forming system and the finish it provided were so satisfactory that the same system is now being used for construction of another residence facility at Stateville, even though this addition is being built by another contractor.