All basement wall and floor panels were completely assembled in three days.
The precast concrete connections were designed for economy, speed of erection, high tolerance levels at the site, high strength, and durability. Precast walls for the second story and the roof beams were installed in two days. All components were erected in five days.
Innovative precast concrete elements such as the sandwich wall panel, floor panel system, and roof beams of the NU Concrete House have proven the potential for preast residential construction, not only for single-family homes in the United States, but also for multi-unit dwellings around the world.
The authors are William Holmes, associate professor, Department of Construction Systems, and David Kusolthamarat, Maher Tadros, and Charles Vranek, all of the University of Nebraska-Lincoln.
This article first appeared in PCI Journal. Visitwww.pci.org.The Conquest of Space
Thin-shell precast concrete has scored a victory in the conquest of space-inner space, that is. Floor space was added to the Domus residential complex in Philadelphia by switching its cladding to a thin-shell precast wall system. This also helped the developer get its buildings enclosed faster, reduce project costs, and improve its architectural appeal.
The $71 million project in University City in Philadelphia is being developed and built by The Hanover Company of Houston. The eight-story complex includes 414,000 square feet of premium residential and retail space, plus 108,000 square feet of parking. The project was originally designed with a masonry finish with complex brickwork to harmonize with the brick facades of the adjacent University of Pennsylvania.
Groundbreaking was scheduled for December 2005, and the developer was anxious to have the building enclosed and watertight before winter. Hanover revised its plans and turned to thin-shell precast concrete cladding to speed erection. It selected Metal Stud Crete, a thin-shell precast concrete wall system that marries 2.5-inch faces of architectural precast concrete to cold-formed steel stud framing using a proprietary connector embedded in the concrete.Saving space
To make the change, Hanover brought in IECS of Warrenton, Va., an engineering firm with previous experience with Metal Stud Crete. Thin-wall precast, “saves quite a bit of space” because the studs provide built-in cavities for utilities and insulation, eliminating the need for an additional furring wall, says Michel Catteau of IECS.
Architectural Precast (API) of Middleburg, Pa., produced the panels. In addition to complicated brick patterns and reveals, as many as three different colors were required on some panels. To harmonize with the masonry on the university campus, API emulated the appearance of limestone, used medium sandblasted finish to reveal aggregates, and an acid etch.