3.3.8
[Placing Concrete Underwater
Concrete, described in Bid Item [_____], shall be deposited in water by a
tremie or concrete pump. The methods and equipment used shall be subject
to approval. Concrete buckets will not be permitted for underwater
placement of concrete except to deliver concrete to the tremie. The tremie
shall be watertight and sufficiently large to permit a free flow of
concrete. The discharge end of the pump line or tremie shaft shall be kept
continuously submerged in the concrete. The underwater seal shall be
effected in a manner that will not produce undue turbulence in the water.
The tremie shaft shall be kept full of concrete to a point well above the
water surface. Placement shall proceed without interruption until the
concrete has been brought to the required height. The tremie shall not be
moved horizontally during a placing operation, and a sufficient number of
tremies shall be provided so that the maximum horizontal flow will be
limited to 5 m 15 feet.]
3.4
FINISHING
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NOTE: Consult the appropriate DM for those surfaces
to receive a trowel finish, abrasive aggregate
finish or broom finish. Be sure those special
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The ambient temperature of spaces adjacent to surfaces being finished shall
be not less than 5 degrees C 40 degrees F. In hot weather when the rate of
evaporation of surface moisture, as determined by use of Figure 2.1.5 of
ACI 305R, may reasonably be expected to exceed 1.0 kg/square meter 0.2
pounds per square foot per hour. Provisions for windbreaks, shading, fog
spraying, or wet covering with a light-colored material shall be made in
advance of placement, and such protective measures shall be taken as
not to be covered by additional concrete or backfill shall have a float
finish. Additional finishing shall be as specified below and shall be true
to the elevation shown in the drawings. Surfaces to receive additional
concrete or backfill shall be brought to the elevation shown on the
drawings and left true and regular. Exterior surfaces shall be sloped for
drainage unless otherwise shown in the drawing or as directed. Joints
shall be carefully made with a jointing or edging tool. The finished
surfaces shall be protected from stains or abrasions. Grate tampers or
jitterbugs shall not be used.
3.4.1
Unformed Surfaces
3.4.1.1
Float Finish
Surfaces shall be screeded and darbied or bullfloated to bring the surface
to the required finish level with no coarse aggregate visible. No water,
cement, or mortar shall be added to the surface during the finishing
operation. The concrete, while still green but sufficiently hardened to
bear a man's weight without deep imprint, shall be floated to a true and
even plane. Floating may be performed by use of suitable hand floats or
power-driven equipment. Hand floats shall be made of magnesium or aluminum.
3.4.1.2
Trowel Finish
A trowel finish shall be applied to the following surfaces:
[_____]
SECTION 03301A
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