2.1.1.4
[Silica Fume
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NOTE: Optional Table 2 in ASTM C 1240 shall be
included when used with aggregates listed to require
low-alkali cement. Other requirements in Table 4
may be specified if necessary. Refer EM 1110-2-2000
for guidance.
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Silica fume may be furnished as a dry, densified material or as a slurry.
Silica fume, unprocessed, or before processing into a slurry or a densified
material, shall conform to ASTM C 1240 with [Table 2 and] the Specific
Surface Area and Uniformity Requirements in Table 4 invoked. The
Contractor shall provide the services of a manufacturer's technical
representative, experienced in mixture proportioning, placement procedures,
and curing of concrete containing silica fume. The manufacturer's
representative shall be available for consultation by both the Contractor
and the Contracting officer during mixture proportioning, planning, and
production of silica-fume concrete and shall be onsite immediately prior to
and during at least the first placement of concrete containing silica fume,
and at other times if directed.]
2.1.1.5
Temperature of Cementitious Materials
The temperature of the cementitious materials as delivered to the site
shall not exceed 65 degrees C 150 degrees F.
2.1.2
Admixtures
All chemical admixtures furnished as liquids shall be in a solution of
suitable viscosity for field use as determined by the Contracting Officer.
2.1.2.1
Air-Entraining Admixtures
The air-entraining admixture shall conform to ASTM C 260 and shall
consistently entrain air in the specified ranges under field conditions.
2.1.2.2
[Accelerating Admixture
Calcium chloride shall not be used. Accelerators shall meet the
requirements of ASTM C 494/C 494M, Type C [(or Type E)].]
2.1.2.3
[Retarding Admixture
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NOTE: A retarding admixture should not be used
where high early strength is desirable so that form
stripping may proceed expeditiously. Before listing
items consult the concrete materials design
memorandum to determine areas where retarders may be
necessary.
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A retarding admixture shall meet the requirements of ASTM C 494/C 494M,
Type B, or D, except that the 6-month and 1-year compressive strength tests
are waived. The admixture may be added to the concrete mixture only when
approved[, except for the following structural items where a retarding
admixture shall not be used: [_____]]. Use of Type D shall not be the
SECTION 03700
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