Reinforcement

Bonding New Concrete, Masonry or Tile to Existing Similar Materials

We’ve had numerous requests received by Pool Engineering, Inc. for recommendations on proper construction techniques for bonding new materials such as masonry, tile, gunite and concrete to an existing cementitious substrate.

It is recommended that the following procedures be followed in bonding new materials to existing for attaining proper bonding:

1. Existing surfaces must be sound, free of defects, clean and free of bond inhibiting materials.
2. Existing surfaces must be roughened by chipping or other suitable means to provide an open pore structure. All loose, cracked or deteriorated materials must be removed.
3. Clean existing surfaces by water blasting.
4. When applying materials other than shotcrete or gunite, the new material should be applied over cement paste or another approved bonding agent, which has been brushed onto the substrate (existing material) for absorption into the pore structure. The new material shall be applied before the cement paste or other approved bonding agent “skins over” or starts it’s “setting stage”.
5. Saturated surface dry condition of the substrate shall be maintained to prevent premature drying of the bonding paste.

Following these recommended practices will minimize problems in attaining proper bonding between these materials and will provide quality results.

Hopefully, this clarifies the issue of bonding new materials such as masonry, tile, gunite and concrete to existing similar materials.

Ron Lacher, P.E.