3.8.5.2
Injection
After crack surface sealer has hardened and cured, pump [epoxy injection
adhesive][polyurethane injection adhesive][ultra-fine cement grout] into
valve at one end of crack. For vertical surfaces start at lowest valve and
work upwards. As crack sealer appears at next valve, pinch pumping valve
closed and move to next valve and commence pumping. Continue procedure
until other end of crack is reached. Avoid delays in pumping operation.
After crack sealer has hardened and cured grind valves off flush with
concrete surface. Coat areas of valves with crack surface sealer and allow
to harden and cure.
3.8.6
Crack Repair with Additional Reinforcement
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NOTE: Repairing cracks with additional reinforcement
is used to stabilize active cracks to permit sealing
and to reestablish tensile strength across cracks.
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Stabilize cracks by anchoring as shown on the drawings.
3.8.6.1
Stitching
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NOTE: When the crack must be made watertight, one
of the methods for sealing or repairing the crack
should be used prior to stabilizing the crack.
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Drill holes of appropriate size and depth for grouting the stitching
staples and at the spacing shown on the drawings. Reduce spacing at ends
of crack. Vary the orientation and length of stitching staples to avoid
applying tension to a single plane within the concrete. If the end of the
crack within the structure can be determined, drill a hole at the end of
the crack to relieve stress concentration. Clean the holes by flushing
with water and compressed air prior to placing grout. Dry surfaces to
receive grout as recommended by the grout manufacturer. Partially fill the
holes with epoxy resin grout and insert the stitching staples into the
holes. Place additional grout and consolidate it by rodding until
remainder of the hole is filled. Place grout with the equipment capable of
supplying, mixing, and placing the grout in the holes in a manner that will
ensure complete filling of the holes and elimination of voids, air pockets,
and water. After placing, allow the grout to set for a period of not less
than 24 hours, and protect the stitching staples against damage. Remove
and reset any stitching staples which are disturbed during curing.
3.8.6.2
Conventional Reinforcement
Drill holes, of a size appropriate for the reinforcement and grout used, at
right angle to the crack plane, and extending a minimum of 0.5 m (18 inches)
18 inches on each side of the crack. Space holes as indicated on the
drawings. Clean the holes by flushing with water and compressed air prior
to placing grout. Insure that holes are dry before placing grout. Inject
epoxy grout at a pressure sufficient to distribute the grout in the hole
but not great enough to cause additional damage to the concrete. Insert
reinforcing bar so that it extends at least 0.5 m (18 inches)18 inches on
each side of the crack. [After grout has set, seal the crack by injection
grouting.]
SECTION 03931
Page 63
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