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Harbor
Under Deck Repairs
Unsound concrete as well as built-up patches were removed and were
abrasive-blasted using copper slag grit (Figure 23). The repair
areas were filled using Sikatop 123 Plus? and their surfaces were
restored flush to the bottom of the deck. The contractor used dry
packing procedures to apply the concrete repair mix on the underside
of the deck (Figures 24 and 25). Dry packing is a repair method
of placing zero-slump or near zero-slump, concrete or mortar by
ramming it into the surface cavities. This method is appropriate
for the small depth cavity repairs typical of the areas below Bravo
25.
A sufficient amount of component B was added to make a mix consistency
that could be hand-molded into a ball. Mixture control is critical
to make a sound, solid pack, with minimum shrinkage and failure.
The “pot life” of a mixture is limited to as little
as 15 minutes. Small volumes were mixed for adequate placement time
before the mixture starts to set. The addition of water was never
allowed to increase the workability of the mixture.
A bonding agent consisting of neat cement was applied between the
original concrete and repair material to promote good bond. Epoxy
bonding agents were not allowed. Dry pack repair was placed in layers
of approximately 1 inch thick. The layers were manually compacted
over the entire area with a hardwood stick and a hammer to increase
the density of the repair material and to improve contact with the
substrate concrete. A minimum thickness of ½-inch of Sikatop?
123 was approved.
Two coats of curing compound (Sonneborn? Cure and Seal) were sprayed
on all repairs as soon as the surfacing was finished.
Figure 23. Unsound concrete removed from area for repair.
Figure 24. Dry pack method of concrete repair.
Figure 25. Handpacking Sikatop© 123 into repair area.
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