Reattaching Bluestone to Concrete Walkway: Clean, Acid Etch, New Mortar Bed

Question: PA bluestone in concrete; stones popped off during remodel. Concrete base sound. Reattach without demo?

Answer: Chisel Old Mortar, Acid Etch, Clean Stone, New Mortar Bed, Tamp, Tool Joints

1. Chisel old mortar to clean concrete.
2. Acid etch with muriatic acid for bond.
3. Scrub stone clean.
4. Mix mortar; spread to match original setting bed thickness (½–1").
5. Dampen stone, press firmly, tamp with rubber mallet on wood block over towel.
6. Scrape excess, wipe joints to match. Wipe hourly ~4 hrs until haze gone.
7. Wait 48 hrs before walking.

—Sean J Murphy | amenityarchitects.com