Contractor quality control (QC) and Government quality control (QA) testing.
3.1.4.2
Coarse Aggregate
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NOTE: The automatic sampling plant should be
required for aggregates in concrete containing
larger than 75 mm (3 inch) NMSA. For aggregates in
concrete containing 75 mm (3 inch) NMSA, a cost
analysis should be made before specifying the
automatic sampling plant. The automatic sampling
plant should not be specified for aggregates in
concrete containing 75 or 150 mm (3 or 6 inch) NMSA.
Note that the quarry sloping screens on the
automatic plant will require slightly larger screens
than those used for tests by ASTM C 136 for
comparable results.
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Suitable facilities shall be provided for readily obtaining representative
samples of coarse aggregate for test purposes immediately prior to the
material entering the mixer. [The facilities shall include automatic
equipment capable of obtaining, sieving, and weighing samples of the coarse
aggregate as follows:
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NOTE: The following table to be used with SI units.
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AGGREGATE SIZE
APPROXIMATE SIZE OF SAMPLE
4.75 to 19.0 mm
250
kg
19.0 to 37.5 mm
250
kg
37.5 to 75 mm
500
kg
[75 to 150 mm
1000
kg]
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NOTE: The following table to be used with IP units.
**************************************************************************
AGGREGATE SIZE
APPROXIMATE SIZE OF SAMPLE
No. 4 to 3/4 inch
500
lb
3/4 to 1-1/2 inch
500
lb
1-1/2 to 3 inch
1,000
lb
[3 to 6 inch
2,000
lb]
The equipment shall be capable of running a complete sieving, of any
required sample, without the necessity of intermittent loading. To
accomplish this, adequate areas of individual sieves and controlled feeding
of samples shall be provided. The assembly shall be designed to permit
selection, screening, and weighing of any individual sample in 10 minutes
or less. The equipment shall be designed by a company engaged in the
design and manufacture of aggregate sieving devices. The Contractor shall
have complete responsibility for providing equipment that will accomplish
SECTION 03700
Page 53
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