weight not exceeding 1850 kg/cubic meter 115 pcf.
1.8.9
Technical Service for Specialized Concrete
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NOTE: Use this paragraph when lightweight aggregate
structural concrete is specified or for other
specialized concretes like those containing silica
fume.
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The services of a factory trained technical representative shall be
obtained to oversee proportioning, batching, mixing, placing,
consolidating, and finishing of specialized structural concrete, such as
[_____]. The technical representative shall be on the job full time until
the Contracting Officer is satisfied that field controls indicate concrete
of specified quality is furnished and that the Contractor's crews are
capable of continued satisfactory work. The technical representative shall
be available for consultation with, and advice to, Government forces.
1.9
MIXTURE PROPORTIONS
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NOTE: This paragraph places the responsibility for
mixture proportioning on the Contractor. Where
Government mix design is required, the entire
paragraph will be revised accordingly. Do not
delete 15 percent minimum for pozzolan, unless
pozzolan is prohibited.
**************************************************************************
Concrete shall be composed of portland cement, other cementitious and
pozzolanic materials as specified, aggregates, water and admixtures as
specified.
1.9.1
Proportioning Studies for Normal Weight Concrete
Trial design batches, mixture proportioning studies, and testing
requirements for various classes and types of concrete specified shall be
the responsibility of the Contractor. Except as specified for flexural
strength concrete, mixture proportions shall be based on compressive
strength as determined by test specimens fabricated in accordance with ASTM
C 192/C 192M and tested in accordance with ASTM C 39/C 39M. Samples of all
materials used in mixture proportioning studies shall be representative of
those proposed for use in the project and shall be accompanied by the
manufacturer's or producer's test reports indicating compliance with these
specifications. Trial mixtures having proportions, consistencies, and air
content suitable for the work shall be made based on methodology described
in ACI 211.1, using at least three different water-cement ratios for each
type of mixture, which will produce a range of strength encompassing those
required for each class and type of concrete required on the project. The
maximum water-cement ratios required in subparagraph Water-Cement Ratio
will be the equivalent water-cement ratio as determined by conversion from
the weight ratio of water to cement plus pozzolan, silica fume, and ground
granulated blast furnace slag (GGBF slag) by the weight equivalency method
as described in ACI 211.1. In the case where silica fume or GGBF slag is
used, the weight of the silica fume and GGBF slag shall be included in the
equations in ACI 211.1 for the term P, which is used to denote the weight
of pozzolan. If pozzolan is used in the concrete mixture, the minimum
SECTION 03300A
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