We at Classic Turf Co. of Woodbury, Conn. designed and built two outdoor basketball courts using post-tensioned concrete.
The problem here in Connecticut is that the soils are very active and the climate is relatively harsh, making asphalt courts unplayable after just a few years because of cracking and uneven settling. We specialize in post-tensioned concrete courts (including tennis, basketball, skate parks, and running tracks) because these post-tensioned slabs are designed to hold up when built on actively moving soils like the ones present in Connecticut. PT slabs don’t crack, settle, or heave, which makes a perfect base for athletic courts like tennis and basketball. They also are built to very tight tolerances of planarity and pitch for optimum performance and durability. Furthermore, post-tensioned concrete slabs don’t require cut joints or expansion joints—we can pour 50,000-square-foot slabs monolithically. No joints not only means a smoother surface to play on or skate on, but gives water one less place to enter.
The two courts were built side by side. The overall slab size is 115x130 feet, or 14,950 square feet. Courts are National Federation of State High School Associations (NFHS) regulation size with four basketball goals. A 10-foot-high custom-built, welded steel frame with vinyl coated mesh fence was built around the perimeter of the courts.
The site was excavated where an old dirt parking lot had been. We removed the top soil down to the hard-pan layer and added 6 inches of gravel and a 2-inch sand base. This area was pitched 1 percent side to side to facilitate drainage of the playing surface.
Two layers of 10-mil poly sheeting was laid inside the formwork (not only as a vapor barrier, but to lessen the restraint due to shrinkage and post-tensioning) and steel post-tensioning cables were installed in both directions. The spacing of the tendons is based on calculations that provide a minimum residual compressive stress at the plan center of the slab of 100 psi. We usually go a little higher than that. A pump truck was used to pour 200 cubic yards of 3000 psi concrete. Our crew placed and finished the concrete in about 4 hours. The next day, the forms were stripped and the cables were tensioned according to Post-Tensioning Institute (PTI) specifications. The concrete was allowed to cure for 28 days (7 of which were a wet cure).
Classic Turf then sealed the concrete with a proprietary breathable adhesive. A grip layer was applied, and acrylic sport surface paint was applied to match the local high school colors: red and black.
The entire construction process (including curing) took 7 weeks. Just after Labor Day weekend the courts were enthusiastically dedicated and opened by the town.