FRP dome forms create waffle slab deck designed to optimize airflow and utility services.

As one of the nation’s top 25 research universities, the Georgia Institute of Technology (Georgia Tech) is poised to advance its position with an $80 million nanotechnology center that will bring together the physical and biological sciences in a unique fusion of disciplines. The Marcus Nanotechnology Building (NRCB) will feature two cleanroom facilities that incorporate a waffle slab deck design built using custom fiberglass reinforced plastic (FRP) dome forms to provide the load rigidity and airflow requirements essential to next-generation nanotechnology research operations.

The NRCB, which broke ground in August 2006, is scheduled for completion in summer 2008. It comprises two areas split by an expansion joint: a five-story laboratory/office area; and a 30,000-square-foot, tri-level design cleanroom. Approximately 20,000 square feet of cleanroom space will be dedicated to nanotechnology physical sciences and engineering, adjacent to a 10,000-square-foot facility dedicated to biological and biomedical nanotechnology research.

The project’s architectural firm, M & W Zander (Stuttgart, Germany and Plano, Texas), specified the waffle slab design for the NRCB cleanrooms to optimize airflow and utility (gas/water) exhaust services throughout the flooring system. The design provides cleanroom filtering by pushing air through the building with uniform velocity and minimum turbulence. Additionally, the dome configuration was specified deep to ensure the slab’s load capacity to support the cleanrooms’ equipment.

FRP dome design

The general contractor, The Whiting-Turner Contracting Company, Baltimore, Md., enlisted the project’s concrete trade contractor, United Forming, Austell, Ga., to source the formwork for the waffle slab. Having eliminated wood and steel options, United Forming awarded the bid to Molded Fiber Glass Construction Products (MFG), Independence, Kan., which manufactures a complete range of custom, one-piece FRP forms. The forms provide a stronger, flexible design that can meet unique configurations, reduce labor, and be reused on future projects.

The custom domes had to be deep and narrow for the void size required for the floor. MFG produced three, rectangular-shaped sizes of forms ranging from 44 inches deep by 18 inches wide by 38 inches long and smaller. Concrete dome pours will be finished 2 inches below the top, creating multiple voids in the slab once the forms are removed. Stripping the forms normally would be difficult because there is a lot of contact surface. However, the FRP’s physical properties, combined with a chemically active release agent called Nox-Crete PCE, eliminate that problem. Workers simply knock out the form with a sledge hammer with no need for blow-plug air devices.

Concrete pour specs and assembly

Six decks require the FRP dome forms. On the first elevated deck, 22,980 square feet will consist of the open top waffle slab, with a 16.5-foot clear story height, while the other 19,875 square feet will be a traditional beam and slab with a 20-foot clear story height. On the first level, the traditional beam and slab design (four sections) will alternate with waffle slab design (six sections). This alternating format allows for optimal concrete pours; the waffle slab pours are made first, then allowed to cure while the beam and slab pours are made. After the domes are stripped and the completed slab is in place, a heavy-duty computer floor will cover the open waffle slab.

According to Georgia Tech building owner Bob Rose, "This unique floor design has more holes than floor as the majority of it is forms. With over 3,000-plus holes in the floor, it’s like a big grate that will facilitate the airflow process. This will create a laminar flow (versus turbulent flow) that will streamline the uniform air velocity for the center’s research productivity."

Eric Brace is engineering manager for MFG Construction Products. He can be contacted at eric@mfgcp.com.