measures have been taken. The mixture proportioning
work shall consider the use of silica fume to
enhance abrasion resistance.
**************************************************************************
ACI 201.2R and ACI 211.1.
For structural elements to be exposed in a
marine environment, adjust
the concrete 28-day design strength to produce
concrete of minimum design
strength (f'c) of 35 MPa 5000 psi. [For
elements subject to severe
abrasion, the minimum design strength (f'c) will
be adjusted to 42 MPa 6000
psi.]
2.1.2
Contractor-Furnished Mixture Proportions
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NOTE: This specification requires that the
structural requirements (f'c) be met. But that, if
the prequalified mixture should produce a higher
strength (fcr), that strength should govern.
Maintain required w/c and w/cm ratio despite
strength requirements.
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a.
Strength and Water-Cementitious Materials Ratio. Strength
requirements shall be based on 28-day compressive strength
determined on 150 by 300 mm 6 by 12 inch cylindrical specimens in
accordance with ASTM C 39. The specified compressive strength of
the concrete (f'c) for each portion of the structure shall meet
the requirements in the contract documents.
b.
The mixture proportions for marine concrete shall be developed by
the Contractor to produce the design strength (f'c) and to provide
durability, workability, and mixture consistency to facilitate
placement, compaction into the forms and around reinforcement
without segregation or bleeding. The requirements for durability
consideration specified in Table 1 and subparagraph "f" below
shall be incorporated in the mixture proportions.
Table 1 - Concrete Quality Requirements
Minimum
Minimum
quantity of
quantity of
cementitious
portland
Exposure
Maximum
material
cement
Zone
Condition
W/CM
kg/m3
kg/m3
Submerged (1)
(a) Directly
0.40
400
300
and tidal (2)
exposed to salt
water
(b) Subject to
0.40
400
300
severe abrasion
__________________________________________________________________
Splash (3)
(a) Directly
0.40
400
300
exposed to salt
water
__________________________________________________________________
Atmospheric (4) (a) Directly
0.40
400
300
exposed to
marine
SECTION 03311
Page 18
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