Concrete Construction – March 2006
For many years, Atlanta’s Egleston Children’s Hospital has provided quality pediatric care for Georgia families. But according to recent projections, the local pediatric population will increase dramatically by 2009, so Children’s Healthcare of Atlanta is expanding and renovating several local children’s hospitals, including Egleston.
As part of the upgrades, a new three-level, attached parking garage is being constructed, using a new and innovative method of building shoring walls, designed by Atlanta’s ABE Enteprises. Rather than digging down to the required depth and installing shoring walls from the bottom up, the ABE wall is built from the top down.
First, H-beams piles are driven deep into the ground around the perimeter of the excavation to the required depth-in this case, 80 feet (24 meters). Five to six feet of dirt are removed, forms are mounted on the H-beams, and concrete tiles measuring 7 feet x 4 feet x 9 inches (2.1m x 102m x 22.5cm) are poured. Once the concrete sets, the forms are removed, an additional 6 feet of dirt is removed, and the process is repeated until the shoring wall is complete.
Paul Mandall, president of Middle Georgia Concrete Construction, says that the project
team chose the ABE shoring wall design for several reasons. “It costs a lot less than other types of shoring walls, and it expedites the construction process.” Because it doesn’t leave room outside the wall for installing conventional waterproofing membranes, however, ABE’s innovative shoring wall design requires an equally innovative concrete waterproofing system.
ABE Enterprises suggested that the general contractor, Brasfield & Gorrie, learn more about the Krystol concrete waterproofing system. The Krystol system turns concrete into a permanent, waterproof barrier. When added to the concrete mix or applied to existing concrete, it causes millions of needle-like crystals to form, filling the spaces between concrete particles, blocking the penetration of water and corrosive elements and resisting hydrostatic pressure. Over time, any water that does seep in causes additional crystals to form, self-sealing any small concrete cracks.
Because it eliminated the need for external membranes, the Krystol system seemed ideal for use with the ABE wall. After preliminary tests proved successful, Brasfield & Gorrie chose the Krystol system to waterproof the Egleston parking structure’s shoring wall. A total of 39,500 pounds (17,917.2 kg) of KIM (Krystol Internal Membrane) and 3500 cubic yards (2676 m3) of KIM-treated concrete were used in the project. To protect the joints between the wall’s concrete tiles, they used Krystol Waterstop System, an advanced joint design system that offers two levels of waterproofing protection.
“The Krystol system worked great,” says Rick Anderson, president of ABE Enterprises. “It saved money for the owners, shortened the construction time, and resulted in stronger, better concrete.” And when a few minor cracks appeared in the finished concrete, he says, “they selfsealed exactly as promised.”
The Egleston parkade should be completed in late 2005 and the entire Egleston Children’s Hospital Upgrade will be finished by 2008. Daily progress at the site can be viewed at www.oxblue.com/clientichoa.
Architect: HKS, Inc., Dallas
Kryton Distributor: The Crystal Group LLP
Concrete Supplier: Thomas Concrete, Atlanta
General Contractor: Brasfield & Gorrie, Birmingham, Ala// Atlanta
Shoring Wall Contractor: ABE Enterprises, Atlanta
Subcontractor to ABE Enterprises: Middle Georgia Concrete Constructors, Atlanta