Sunbelt Performs Largest Cap Pour in Ga.’s History

A fast growing Gwinnett County has prompted the Gwinnett County Board of Commissioners to build a 6 mi. extension of the Sugarloaf Parkway in an attempt to reduce commuter traffic congestion.

Sunbelt Structures of Tucker, Ga., specializes in all components of interstate highway interchange construction. Awarded the $21 million contract by the Gwinnett County Board of Commissioners, Sunbelt began work in mid-February 2009 with an anticipated completion date of early 2011. The complete project consists of a new interchange, a four-lane highway, three new bridges, and dozens of reinforced earth walls and box culverts.

A major concern for Gwinnett County and Sunbelt Structures was to reduce the environmental impact of the construction, as the extension of Sugarloaf Parkway would pass through wetland and watershed areas. They chose single stem pier design with a hammer head cap to minimize the number of footings. The ability to set the cap forms with a single crane pick and strip them in two picks provided the most economical forming solution for this project.

The EFCO plate girder system was the first and only consideration for the construction of the project’s 13 piers and hammerhead caps based on the experience of Sunbelt General Superintendent, Herb Jordan and Superintendent, Doug Archer. They chose a fixed soffit solution and formed the varying slopes with blockouts to eliminate additional assembly for each configuration. EFCO designed a soffit form using the EFCO super stud for additional support to form the 6 ft.

(1.8 m) wide soffit and multiple blockouts.

EFCO engineers provided detailed drawings showing the size and placement of the blockouts provided by Sunbelt along with details explaining how to assemble and cycle the cap formwork. The cap size also varied from 49 ft. 6 in. (15.1 m) to 69 ft. 3 in. (21.2 m) in length and 9 ft. (2.7 m) to 15 ft. (4.6 m) in height. All caps measured 6 ft. in width and cycled in two halves. Column measurements ranged from 9 ft. by 6 ft. to 14’ft. by x 6 ft. (4.3 by 1.8 m), and the maximum height was 46 ft. 3 in. (14.1 m).

The plate girder system is performing as expected, providing the contractor with an architectural concrete finish with on-time and on-budget results. GA DOT reported that the largest cap poured on this project is the largest on state history.