3.2.3
Exposed Reinforcement
Concrete shall be removed from around exposed or deteriorated reinforcing
steel. Steel shall stand free of concrete at least 25 mm 1 inch minimum to
provide mechanical bond with patch material.
3.2.4
Excavation in Concrete
Deteriorated areas indicated to be repaired shall be excavated to sound
concrete. The use of concrete and masonry saws for outlining the
excavation shall not be used. The excavation shall be accomplished by use
of manual methods and low-energy, handheld equipment. The sides of the
excavation shall be approximately perpendicular to the exposed surface,
dovetailed back 15 degrees from perpendicular to the exposed surface at the
bottom in order to key in the patch. The bottom (or back) of the
excavation shall be approximately parallel with the exposed surface of the
patch. The surfaces of the excavation shall be finished to remove
excessive variations and roughness and shall be shaped to provide a patch
with uniform dimensions. Feathering at edges shall not be permitted. The
excavation shall be accomplished to minimize the appearance of bond lines
between the patch and the adjacent concrete and other abutting surfaces.
Surfaces of the structure and surfaces adjacent to the excavation shall be
protected from damage which may result from excavation operations.
3.2.5
The surfaces of the excavation shall be cleaned by water blasting and
manual scrubbing methods. Sandblasting shall not be used to clean concrete
surfaces. The surfaces of excavations shall be cleaned of dust, dirt,
laitance, corrosion, or other contamination. Cracks and voids shall be
flushed out with clean water and allowed to dry. Concrete surfaces to be
in contact with the freshly placed concrete shall be maintained in a
continuously damp condition for at least 24 hours prior to concrete
placement. Immediately before placement, areas to be patched shall be
cleaned and rinsed, followed by blowing dry with filtered, dry, compressed
air to remove excess water, and to provide a surface in a saturated,
surface-dry, damp condition. Surfaces of the structure and surfaces
adjacent to the excavation shall be protected from damage which may result
from cleaning operations.
3.2.6
Previously Repaired Cracks
Old caulking or grout shall be removed from previously repaired cracks
where it is failing. Loose particles shall be removed from cracks. Cracks
shall be cleaned, rinsed with water followed by blowing with filtered, dry,
3.3
REINFORCING STEEL
3.3.1
Cleaning
Exposed reinforcing steel shall be mechanically cleaned to bare metal.
Exposed steel in areas to be patched shall be painted with two coats of
zinc-rich primer paint.
3.3.2
Repairing
The Contracting Officer shall be notified of any steel members which have
significant loss in cross-sectional area due to corrosion, cutting, or
SECTION 03900
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