not extend reinforcement or other embedded metal items bonded to the
concrete through any expansion joint unless an expansion sleeve is used.
Provide contraction joints, either formed or saw cut or cut with a jointing
tool, to the indicated depth after the surface has been finished. Sawed
joints shall be completed within 4 to 12 hours after concrete placement.
Protect joints from intrusion of foreign matter.
3.5
BATCHING, MEASURING, MIXING, AND TRANSPORTING CONCRETE
ASTM C 94/C 94M, ACI 301, ACI 302.1R, and ACI 304R, except as modified
herein. Batching equipment shall be such that the concrete ingredients are
consistently measured within the following tolerances: 1 percent for cement
and water, 2 percent for aggregate, and 3 percent for admixtures. Furnish
mandatory batch ticket information for each load of ready mix concrete.
3.5.1
Measuring
Make measurements at intervals as specified in paragraphs entitled
"Sampling" and "Testing."
3.5.2
Mixing
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NOTE: For WESTNAVFACENGCOM projects located at
Marine Corps Base, Camp Pendleton, California,
delete the first bracketed sentence.
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ASTM C 94/C 94M and ACI 301. Machine mix concrete. Begin mixing within 30
minutes after the cement has been added to the aggregates. [Place concrete
within 90 minutes of either addition of mixing water to cement and
aggregates or addition of cement to aggregates if the air temperature is
less than 29 degrees C (85 degrees F) 85 degrees F.] Reduce mixing time
and place concrete within 60 minutes if the air temperature is greater than
29 degrees C (85 degrees F) 85 degrees F except as follows: if set
retarding admixture is used and slump requirements can be met, limit for
placing concrete may remain at 90 minutes. Additional water may be added,
provided that both the specified maximum slump and water-cement ratio are
not exceeded. When additional water is added, an additional 30 revolutions
of the mixer at mixing speed is required. [If the entrained air content
falls below the specified limit, add a sufficient quantity of admixture to
bring the entrained air content within the specified limits.] Dissolve
admixtures in the mixing water and mix in the drum to uniformly distribute
the admixture throughout the batch.
3.5.3
Transporting
Transport concrete from the mixer to the forms as rapidly as practicable.
Prevent segregation or loss of ingredients. Clean transporting equipment
thoroughly before each batch. Do not use aluminum pipe or chutes. Remove
concrete which has segregated in transporting and dispose of as directed.
3.6
PLACING CONCRETE
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NOTE: When necessary to deposit concrete under
water, add the following paragraph:
"Depositing Concrete Under Water.
SECTION 03300N
Page 34
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