temperatures before the expiration of the curing period, it shall be placed
in accordance with procedures previously submitted in accordance with
paragraph SUBMITTALS. The ambient temperature of the space adjacent to the
concrete placement and surfaces to receive concrete shall be above 0
degrees C 32 degrees F. The placing temperature of the concrete having a
minimum dimension less than 300 mm 12 inches shall be between 12 and 24
degrees C 55 and 75 degrees F when measured in accordance with ASTM C
1064/C 1064M. The placing temperature of the concrete having a minimum
dimension greater than 300 mm 12 inches shall be between 10 and 20 degrees
C 50 and 70 degrees F. Heating of the mixing water or aggregates will be
required to regulate the concrete-placing temperatures. Materials entering
the mixer shall be free from ice, snow, or frozen lumps. Salt, chemicals,
or other materials shall not be mixed with the concrete to prevent freezing.
3.3.5
Hot-Weather Placing
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NOTE: See the appropriate DM for the proper placing
temperature.
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Concrete shall be properly placed and finished with procedures previously
submitted in accordance with paragraph SUBMITTALS. The concrete-placing
temperature shall not exceed [_____] degrees C F when measured in
accordance with ASTM C 1064/C 1064M. Cooling of the mixing water and
aggregates, or both, may be required to obtain an adequate placing
temperature. A retarder meeting the requirements of paragraph
WATER-REDUCING OR RETARDING ADMIXTURES may be used to facilitate placing
and finishing. Steel forms and reinforcement shall be cooled prior to
concrete placement when steel temperatures are greater than 50 degrees C
120 degrees F. Conveying and placing equipment shall be cooled if
necessary to maintain proper concrete-placing temperature.
3.3.6
Immediately after placement, each layer of concrete, including flowing
concrete, shall be consolidated by internal vibrating equipment. Vibrators
shall not be used to transport concrete within the forms. Hand spading may
be required, if necessary, with internal vibrating along formed surfaces
permanently exposed to view. Form or surface vibrators shall not be used
unless specifically approved. The vibrator shall be inserted vertically at
uniform spacing over the entire area of placement. The distance between
insertions shall be approximately 1-1/2 times the radius of action of the
vibrator. The vibrator shall penetrate rapidly to the bottom of the layer
and at least 150 mm 6 inches into the preceding unhardened layer if such
exists. It shall be held stationary until the concrete is consolidated and
then withdrawn slowly.
3.3.7
[Placing Concrete in Ogee Section
The unformed portion of the ogee section shall be finished by placing
concrete slightly above grade and striking off to grade by accurate
screeding. Screeding may be accomplished by semimechanical devices or by a
mechanical screed that consolidates and screeds the surface in one
operation. Ribs embedded in the fresh concrete as guides for screeds will
not be permitted.]
SECTION 03301A
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