consolidating concrete shall be at the placing site and in proper working
order. Equipment and material for curing and for protecting concrete from
weather or mechanical damage shall be at the placing site, in proper
working condition and in sufficient amount for the entire placement. When
hot, windy conditions during concreting appear probable, equipment and
material shall be at the placing site to provide windbreaks, shading,
fogging, or other action to prevent plastic shrinkage cracking or other
damaging drying of the concrete.
3.1.1
Foundations
3.1.1.1
Concrete on Earth Foundations
Earth (subgrade, base, or subbase courses) surfaces upon which concrete is
to be placed shall be clean, damp, and free from debris, frost, ice, and
standing or running water. Prior to placement of concrete, the foundation
shall be well drained and shall be satisfactorily graded and uniformly
compacted.
3.1.1.2
Preparation of Rock
Rock surfaces upon which concrete is to be placed shall be free from oil,
standing or running water, ice, mud, drummy rock, coating, debris, and
loose, semidetached or unsound fragments. Joints in rock shall be cleaned
to a satisfactory depth, as determined by the Contracting Officer, and to
firm rock on the sides. Immediately before the concrete is placed, rock
surfaces shall be cleaned thoroughly by the use of air-water jets or
sandblasting as specified below for Previously Placed Concrete. Rock
surfaces shall be kept continuously moist for at least 24 hours immediately
prior to placing concrete thereon. All horizontal and approximately
horizontal surfaces shall be covered, immediately before the concrete is
placed, with a layer of mortar proportioned similar to that in the concrete
mixture. Concrete shall be placed before the mortar stiffens.
3.1.1.3
Excavated Surfaces in Lieu of Forms
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NOTE: Delete this paragraph when forms are required.
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Concrete for [footings] [and] [walls] may be placed directly against the
soil provided the earth or rock has been carefully trimmed, is uniform and
stable, and meets the compaction requirements of Section 02300 EARTHWORK.
The concrete shall be placed without becoming contaminated by loose
material, and the outline of the concrete shall be within the specified
tolerances.
3.1.2
Previously Placed Concrete
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NOTE: If structure has few construction joints to
be bonded, none of them critical, remove the
following requirements except for subparagraph
Preparation of Previously Placed Concrete.
Otherwise, use the following requirements and remove
subparagraph Preparation of Previously Placed
Concrete.
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SECTION 03300A
Page 32
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