2.2
CONCRETE
2.2.1
Contractor-Furnished Concrete Mix Design
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NOTE: Insert the specified compressive strength,
f'c. Consider reducing average overstrength factor
to produce a more economical concrete mix design,
since these piles are not critical structural
elements. ACI 318M/318RM may be modified for a
specified compressive strength, f'c, over 35 MPa
5000 psi to permit a required average compressive
strength, f'cr, of f'c plus 4.8 MPa 700 psi.
Concrete may be proportioned in accordance with ACI
214R for the probability of 1 test in 10 falling
below the specified compressive strength, f'c, if
the mix design reflects actual concrete plant
standard deviations and the resulting production
concrete conforms to specified requirements. Do not
use lightweight or fiber-reinforced concrete.
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Concrete shall have a minimum specified compressive strength, f'c, of
[_____] psi at 28 days. The minimum cement content shall be 354 kg/cu.
meter 600 pounds per cubic yard of concrete. The design shall be prepared
in accordance with ACI 211.1 or ACI 318M/318RM. The mix design shall be
based on current materials previously evaluated by the concrete producer
whose established methods of statistical quality control is in conformance
with ACI 318M/318RM. In the absence of such data, the Contractor shall
sample and test the aggregates for the design of concrete.
2.2.2
Concrete Mix Design Proportioning
a.
Water and cement ratio shall be equal to or less than 0.40. If
fly ash is used, the water and cement ratio shall be calculated as
the weight of water divided by the weight of cement plus 60
percent of the weight of fly ash. If silica fume is used, the
water and cement ratio shall be calculated as the weight of water
divided by the weight of cement plus the weight of silica fume.
b.
Maximum aggregate size shall not exceed 19 mm 3/4 inch.
c.
Air-entrainment shall be 5 to 8 percent. Determine air void
structure in accordance with ACI 212.3R. Spacing factor shall be
less than 2.5 mm 0.01 inch, the specific surface area shall be
greater than 0.39 square meter per 0.000016 cubic meter 600 square
inches per cubic inch of air void volume, and the number of air
voids per mm inch of traverse shall be significantly greater than
the numerical value of the percentage of air in the concrete.
2.2.3
Trial Mixtures
Trial mixtures having proportions and consistencies of the proposed mix
design shall be made to document the Contractor's ability to produce
workable concrete which does not segregate or show excessive slump loss
characteristics.
SECTION 02395
Page 14
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