19 June 2001
CR-3: REPAIRS TO CONCRETE SEAWALL
: Sulphate attack has caused limited disintegration
of the seawall within
the tidal zone.
Description of Repairs: Contact between the existing concrete and seawater is
eliminated by adding a repair layer of sulphate-resisting concrete. Old concrete is
replaced only to the extent necessary to repair damage and to isolate the old
concrete from the seawater reaction. See Figure 7-4.
Repair procedures are as described in CPM-3 for cast-in-place concrete, or
CPM-5 if the tremie method is required. Also, see repair CR-8 for certain
Type "A" Repair: In this case, a minimum of 20 cm (7 7/8 inch) of the existing
wall thickness must be sound concrete. A facia of new concrete is added, well
anchored to the existing wall.
Type "B" Repair: In this case, a section of the wall is replaced, through its
entire width, which includes the facia on the water side. This type of repair uses
the dry pack method, CPM-2, to close the gap between the top of the new
concrete and the existing concrete. See CR-8 and Figure 7-7 for a similar wall
Application: These types of repair are applicable where the extent of the
deterioration is limited and is not threatening to the entire height of the seawall,
and a partial repair from foundation to above high water will solve the problem.
The wall foundation must be in good condition. Extensive deterioration along a
length of the seawall would call for a complete demolition and replacement of a
section of wall.