performance specified, and the use is approved by the Contracting
Officer.
(2) The weight of ground granulated blast-furnace slag conforming
to ASTM C 989 shall not exceed 50 percent of the weight of cement.
The slag used in manufacture of a Type IS or ISM blended
hydraulic cement conforming to ASTM C 59/C 59M5M ASTM C 59/C 59M5
shall be included in the calculated percentage. Higher percentage
of ground granulated blast-furnace slag may be used if tests are
made using actual job materials to ascertain the early and later
age strengths and durability performance specified, and the use is
approved by the owner.
(3) The maximum silica fume content shall not exceed 10 percent
by mass of the cementitious material. The silica fume shall
originate from the manufacture of silicon metal and ferro-silicon
alloys. A high-range water reducer shall be used with silica fume
for proper dispersion of the silica fume.
(4) The minimum amount of portland cement is 50 percent of the
total mass of cementitious material.
d.
Air Content. Concrete that will be subject to destructive
exposure (other than loading and wear in a passive environment)
such as freezing and thawing, severe weathering, or deicing
chemicals shall be air entrained and shall conform to the air
limits specified in ACI 301.
e.
Slump. The concrete mixture shall be proportioned to have, at the
point of deposit, a maximum slump of 4 inches as determined by
ASTM C 143. Where an ASTM C 494, Type F or G admixture is used,
the slump after the addition of the admixture shall be no less than
150 mm 6 inches nor greater than 200 mm 8 inches. Slump
tolerances shall comply with the requirements of ACI 117.
f.
Chloride Ion Penetration. To ensure the durability of concrete in
marine environment, concrete shall be proportioned to have the
chloride ion penetration test in accordance with ASTM C 1202, and
be below 750 coulombs for concrete specimens tested at 28 days.
[Alternatively, a ponding test in accordance with AASHTO T 259 may
be performed to validate chloride ion penetration in accordance
with ASTM C 1202.]
2.1.3
Required Average Strength of Concrete
The minimum compressive strength (fcr) of the selected mixture shall equal
or exceed the strength required under ACI 301 for laboratory mixture
designs and which passes the test indicated in the subparagraph entitled
"Chloride Ion Penetration." The average compressive strength produced
under field tests shall be the minimum compressive strength (fcr) required
during construction.
2.2
MATERIALS
2.2.1
Cement
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NOTE: Acceptable types of cement are as follows:
SECTION 03311
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