519 Patching of Concrete Structures

Removal of Disintegrated Concrete (519.03)

It is essential that all unsound concrete be removed.  The use of a hammer will be necessary to sound tight areas, and the use of a sounding chain will speed up deck sounding.  The practice of removing additional sound concrete after the deteriorated material is removed helps to ensure a stable surface to pour against. 

Pay special attention to the locations at the edges of the patch where the reinforcing steel enters the sound concrete.  In many cases, during the removal process, the reinforcing steel is vibrated or impacted, which causes cracking around the reinforcing steel penetration point.  If this occurs, the Contractor will have to “chase” the cracks to make sure all fractured concrete is removed.


Placing, Finishing, and Curing of Concrete (519.06)

It is very difficult to get proper consolidation of a vertical patch.  It may be necessary for the Contractor to utilize a “pencil” vibrator and/or externally vibrate the forms to assist in consolidation.  In all cases, the Contractor is responsible to provide a well consolidated patch. 

Make sure all form ties and form attachment points in both the new concrete and the existing sound concrete are repaired after formwork removal.     


Documentation Requirements - 519 Patching Concrete Structures

1.      Document the patch depth of 4 inches (10 cm) for horizontal patches and the patch depth of 3 inches (8 cm) for vertical patches as per 519.03.

2.      Patch area thoroughly cleaned with water, compressed air, etc.

3.      Concrete testing data and batch tickets for Class S or QC-2 concrete, as specified in the plans. 

4.      Exposed area of patch given a rubbed finish and cured as per 511.14.

5.      Sound patches before final acceptance.

6.      Measure length and width for pay.