Kansas City’s historic American Royal got its start way back in 1899 and today draws more than 250,000 people over an annual 8-week season of barbeque contests, rodeos, livestock shows, equestrian events, and agricultural activities benefiting youth and education. The 14-acre complex’s buildings, though, have a problem common to the confluence of the Missouri and Kansas rivers—the soil beneath them sinks and concrete slab floors become uneven.

Like most of the Kansas City metropolitan area, the land on which American Royal stands is an ancient riverbed and contains thick limestone, channel sandstone, and shale. While the mix can be a solid, stable base, sometimes the supporting geology shifts and presents challenges for concrete sidewalks and slab floors.

The floor of Governor’s Exposition Hall began shifting back in the 1980s, and the remedy was to fill the voids with asphalt and eventually to apply asphalt over the slab for a level surface. Finally last year the American Royal management was faced with a tough choice—find a better, more permanent solution, or tear up the entire floor and replace it. “That would have cost us millions of dollars,” says Dean Barrett, deputy director at Kansas City’s Department of Convention and Entertainment Centers. “I read about polyurethane geotechnical foam and called around to learn more. We put the job out for bid and chose the local company Pro Foundation Technology, Inc., Raytown, Mo., from the many we received from across the country.”

Joe Morgan of Pro Foundations says his company got to work “foamjacking”—a relatively new term based on “mudjacking” in which a water, sand, and cement grout is pumped under a concrete slab to lift it to its original level position. Foamjacking uses polyurethane geotechnical foam instead of the mud slurry. The polyurethane foam is lighter than grout so it doesn’t overburden the soil, and it has enough compressive strength to handle the weight of the slab.

“TerraThane, is an ideal product for void filling and concrete lifting,” says Morgan. “We use this specially formulated, dense foam system made by NCFI Polyurethanes, Mount Airy, N.C. We drilled through 30 inches to 36 inches of asphalt and concrete, pumped the two-part foam into the holes to fill the voids, then raised the slabs to level.”

Morgan says his firm has been using TerraThane instead of mudjacking for more than 4 years because it is more efficient, economical, requires less-to-no maintenance, and is safer to apply. “Equipment for the old mudjacking method has lots of moving parts and can cause injuries. Foamjacking is much simpler with the application process using only one moving part.”

Barrett says Kansas City is pleased with the successful results of the Dec. 2011 work. “We’ve got a level floor and it saved us millions of dollars. We’ll be using it again for other projects here at American Royal.”

To learn more about TerraThane, visit NCFI Polyurethanes at www.terrathane.com.