Clean the concrete surface with a power washer or garden hose. Let the surface dry overnight.
Mix a batch of concrete in a wheelbarrow, following the manufacturer’s directions. Add enough water to make the concrete the consistency of pudding.
Add color pigments to the concrete for the type of slate you want to replicate. Follow the packaging directions for the proper mixing and amount for the area of concrete you are resurfacing.
Pour the wet concrete onto the cracked concrete surface. Smooth a 1-inch layer of concrete with a trowel or a long board for larger areas. Let the concrete dry for two to three hours or until you can press your finger into the surface of the concrete 1/2-inch and meet some resistance.
Sprinkle the surface of the concrete with a powdered release agent by hand. Apply a thin coat to any area you plan to refinish by stamping.
Place the first concrete stamp on top of the concrete and press it down lightly with the palm of your hand. Position a second stamp next to the first one, making sure they are snug and locked together. Place any additional stamps into the concrete, locking their edges together. Press the stamps into the concrete surface with a hand tamper. Let the stamps sit for five minutes before proceeding.
Lift up the first stamp and move it into position next to the last stamp you placed. Continue to move the stamps across the concrete surface, interlocking the edges and tamping before moving them.
Let the concrete dry overnight then sweep away away the powdered release agent. Spray the surface of the concrete with the power washer or garden hose to remove any remaining powder.
Let the surface of the concrete dry for 24 to 48 hours. Apply a concrete sealer to the surface. Follow the manufacturer’s directions for proper application and drying times.