broomable mixture containing approximately 280 to 355 kg 475 to 600 pounds
of portland cement and 135 to 180 kg 225 to 300 pounds pozzolan per cubic
meter yard. The bedding mortar will have 9.5 mm 3/8-inch nominal maximum
size aggregate and a slump, when placed, of 175 to 225 mm 7 to 9 inches.
The bedding concrete, 75 to 100 mm 3 to 4 inch slump conventional concrete,
shall contain 19.0 mm 3/4-inch nominal maximum size aggregate and
approximately [_____] kg pounds of portland cement and pozzolan per cubic
meter yard. The air content of the bedding concrete as delivered to the
placement site shall be between 4.5 and 7.5 percent. [Preliminary mixture
proportioning studies are available for review in the District office.]
Concrete mixtures used for [the upstream face] [, and _____,] and other
conventional concrete mixtures shall contain from [_____] to [_____] kg
pounds of cementitious materials and the slump shall be between 25 and 100
mm 1 and 4 inches.
2.2.3
Proportioning Responsibility
The proportions of all materials entering the RCC and the conventional
concrete will be furnished. The proportions will be changed as necessary
by the Government. Adjustments will be made to the batch weights,
including cement, pozzolan, and water, to maintain the necessary
consistency to prevent segregation within the RCC and allow full compaction
as determined. Frequent changes to the batch weights shall be considered
usual and can be expected to occur frequently during the course of each
day's placement depending on such variables as humidity, wind velocity,
temperature, and cloud cover. Such changes will be as directed. The
Contractor will be responsible for adjusting the added water to compensate
for changes in aggregate moisture content and to adjust the amount of
air-entraining admixture (if used) to keep the percent of air within the
specified range.
2.2.4
Nominal Maximum Size of Aggregate
The nominal maximum size of coarse aggregate to be used in the various
parts of the work shall be in accordance with following:
NOMINAL MAXIMUM SIZE
FEATURES
AGGREGATE
[RCC used in the main concrete gravity dam]
75 mm (3 in.)
[RCC used in construction of the [_____]]
[Conventional concrete for the upstream face]
[Conventional concrete for the [_____]]
[RCC used in the [_____]
37.5 mm (1-1/2 in.)]
[RCC used in the [_____]]
[Conventional concrete for [_____]]
[Conventional concrete bedding mixture]
19.0 mm (3/4 in.)
[Bedding mortar]
4.75 mm (No. 4)
Note: The nominal maximum size aggregate may be changed for applications
requiring a special quality of concrete as directed.
2.2.5
Consistency of RCC
The Contracting Officer will determine at the placement site on a
continuing basis the proper consistency necessary for adequate hauling,
spreading, and compacting and will direct all necessary changes to achieve
the proper RCC consistency. Changes will be directed based on visual
examination of the RCC during the spreading and compaction process and on
SECTION 03701
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