2.3.3
Aggregates
Fine aggregate for sand-cement grout shall conform to ACI 301 and [ASTM C 33
for grout for backfilling holes] [or ASTM C 144 for grout for
pregrouting]. Aggregates shall not contain substances which may be
deleterioulsy reactive with alkalies in the cement.
2.3.4
Admixtures.
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NOTE: Accelerators are not permitted because of
concern that they may cause corrosion of the
prestressing steel. Only plasticizers or retarders
should be permitted when necessary for hot
conditions or long pumping distances.
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Admixtures which control bleed, improve flowability, reduce water content
and retard set may be used in the grout subject to the approval of the
Contracting Officer. Any admixtures used shall be compatible with the
prestressing steel and shall be mixed in accordance with the manufacturer's
recommendations.
2.3.5
Grout for Anchors
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NOTE: Ground and rock ambient temperatures may only
have an effect on the grout when they are below 10
degrees C (50 degrees F) or when polyester resin
grout is used. If unusual ground or rock
temperatures are known to exist, this information
should be provided to the contractor
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2.3.5.1
Cement Grout
Cement grout mixture proportions shall be the responsibility of the
Contractor. Grout for grouting anchors shall consist of a homogenous,
pumpable, stable mixture of portland cement and water. The Contractor
shall submit his proposed mix design to the Contracting Officer for approval.
The water content shall be the minimum necessary for proper placement but
the water-cement ratio shall not exceed [0.45] [_____] by weight. Final
proportions of materials shall be based on results of tests made on sample
mixtures of grout. The minimum compressive strength of two-inch cubes,
molded, cured, and tested in accordance with ASTM C 109/C 109M, shall be
[24.1] [_____] MPa [3,500] [_____] psi at the time of stressing. The
Contractor shall be responsible for taking, curing, and breaking of grout
test cubes for determining mix design, and all testing shall be done by an
independent laboratory approved by the Contracting Officer. [[Soil] [Rock]
conditions and temperatures shall be replicated in the curing process.]
2.3.5.2
Polyester Resin Grout
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NOTE: Polyester resin grout should not be used for
anchors installed in wet holes. Single stage
grouting can be accomplished with polyester resin
grout by using fast setting resin grout in the bond
zone and slower setting resin grout in the free
SECTION 02490
Page 24
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