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.