How to Repair a Bluestone Patio

Remove the broken or damaged stones. Bluestone is normally set in packed sand with more packed sand filling the joints between stones, so you can pry the stone(s) out of the way with minimal effort using the chisel for leverage. For grouted stones, use a hammer and chisel to remove the grout around the stone, and then pry the stone loose.

Replace the old stone with a new piece of bluestone. If you cannot find a piece of bluestone that matches the dimensions of the old one exactly, use the hammer and chisel to break off sections of a piece until it fits into the area you need it to go. Apply a new layer of sand under the stone and tamp it down before putting the stone in place, then tamp the stone into the sand with the mallet until it is flush with the other stones.

Fill in the joints around the new piece of stone. For a dry installation, fill the joints around the stone with sand and pack it into the joint with the mallet until it is full of sand. Top it off with additional sand, and tamp that in place with the rubber end of the mallet. Sweep the excess sand into the other joints.

Grout the stone in place if it is a cement-based bluestone patio. Mix the cement according to the manufacturer's instructions, and fill the joints surrounding the piece of stone. Press the cement into the joints with a grout float. Let the cement dry for 20 minutes, and then clean the excess off with a damp sponge and smooth the joints. Wait a minimum of 24 hours before you allow any foot traffic on the repaired patio.