Delamination

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Delamination of Concrete

delamination

Diagnosis: Delamination is a separation, splitting or de-bonding of the concrete’s thickness along a plane parallel to the surface. Spotted visually if the deterioration is advanced or audibly by tapping the area with a hammer, dragging a piece of steel chain across the surface, or using a specially designed roller tool.

Cause: Inadequate consolidation during placement (cold joint), trapped bleed water, failure of a topping at the bond line, inadequate concrete cover over reinforcing steel, water intrusion (freeze/thaw cycle), and corrosion/expansion of the reinforcing steel.

Prevention: Greater care in lift placement and consolidation, allowing more time for bleed water to dissipate before closing the surface, proper curing and sealing measures to prevent moisture ingress, and checks to insure minimum concrete cover over steel is provided.

Possible concrete repair methods:

delamination diagram

Copyright Halsall 2011

Structural: Once again if the delamination extends to or beyond the reinforcing steel it must be treated as a structural repair.

  • Sound the affected area and delineate perimeter.
  • Saw- cut perimeter to a minimum ½” deep.
  • Chip unsound material down to a minimum depth of ½” beyond the reinforcing.
  • Depending on the extent of corrosion, remove, replace, and/or clean, and prep reinforcing steel. Removal and replacement will require grouting dowels into the existing.
  • Saturate surfaces (SSD)
  • Apply bond scrub coat
  • Patch with a high performance mortar. The selection of exactly which mortar will depend on specifics such as location (horizontal, vertical, or overhead), depth, most efficient placement method, and other characteristics like fiber-reinforcement, corrosion inhibitors.
  • Cure and seal.

Functional/aesthetic only:

  • Depending on repair depth and traffic (for slabs). Saw-cut perimeter of repair area to a minimum depth of ¼” (For durability, never attempt a feather-edged repair in an exterior traffic area)
  • Saturate (SSD)
  • Apply bond scrub coat
  • Patch with a mortar appropriate to depth and traffic cure.

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