of the fine aggregate changes by 0.5 percent or more, the scale
settings for the fine-aggregate batcher and water batcher shall be
adjusted (directly or by means of a moisture compensation device) if
necessary to maintain the specified slump.
3.4.2.2
Coarse Aggregate
a. Grading - At least once during each shift in which the concrete
plant is operating, there shall be a sieve analysis in accordance with
ASTM C 136 for each size of coarse aggregate. The location at which
samples are taken may be selected by the Contractor as the most
advantageous for production control. However, the Contractor shall be
responsible for delivering the aggregate to the mixer within
specification limits. A test record of samples of aggregate taken at
the same locations shall show the results of the current test as well
as the average results of the five most recent tests including the
current test. The Contractor may adopt limits for control which are
coarser than the specification limits for samples taken at locations
other than as delivered to the mixer to allow for degradation during
handling.
b. Corrective Action for Grading - When the amount passing any sieve
is outside the specification limits, the coarse aggregate shall be
immediately resampled and retested. If the second sample fails on any
sieve, that fact shall be reported to the Contracting Officer. Where
two consecutive averages of five tests are outside specification
limits, the operation shall be considered out of control and shall be
reported to the Contracting Officer. Concreting shall be stopped and
immediate steps shall be taken to correct the grading.
c. Coarse Aggregate Moisture Content - A test for moisture content of
each size group of coarse aggregate in accordance with ASTM C 566 or
COE CRD-C 112 shall be made at least once during a shift. When two
consecutive readings for smallest-size coarse aggregate differ by more
than 1.0 percent, frequency of testing shall be increased to that
specified above for fine aggregate, until the difference falls below
1.0 percent.
d. Coarse Aggregate Moisture Corrective Action - Whenever the moisture
content of any size of coarse aggregate changes by 0.5 percent or more,
the scale setting for the coarse aggregate batcher and the water
batcher shall be adjusted if necessary to maintain the specified slump.
3.4.2.3
Quality of Aggregates
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NOTES: Tests should be those listed in paragraph
QUALITY. The petrographic examination shall be used
to identify deleterious substances in aggregates.
Deleterious substances shall be listed individually
with respective limits.
Depending upon the quality of aggregates available,
some tests may not be required. Refer to EM
1110-2-2000 for the purpose of each test.
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a. Frequency of Quality Tests - Thirty days prior to the start of
concrete placement the Contractor shall perform all tests for aggregate
SECTION 03373
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