Ardex SD-P Rapid Self-Drying, Trowelable Concrete Underlayment is formulated with a special blend of Portland cement, other hydraulic cements and polymers. It is a self-drying, fast setting, trowelable patch for smoothing and repairing concrete floors, ramps and stairways, as well as non-porous substrates such as terrazzo, ceramic and quarry tile, prior to the installation of floor covering. Installs from 1/16 inch thick up to 3 inches thick with aggregate. Flooring can be installed over Ardex SD-P Rapid in as little as 1 hour (depending on flooring materials).