b. Corrective Action for Deleterious Substances - When the results for
a deleterious substance are out of the specification limit, the
aggregate shall be resampled and retested for the deleterious substance
that failed. If the second sample fails, that fact shall be reported
to the Contracting Officer. When material finer than 75-m (No. 200)
sieve for coarse aggregate exceeds the specification limit, immediate
steps, such as washing or other corrective actions, shall be initiated.
3.4.2.5
Scales
a. Accuracy - The accuracy of the scales shall be checked by test
weights prior to start of concrete operations and at least once every 3
months for conformance with the applicable requirements of paragraph
BATCHING EQUIPMENT. Such tests shall also be made as directed whenever
there are variations in properties of the fresh concrete that could
result from batching errors.
b. Batching and Recording Accuracy - Once a week the accuracy of each
batching and recording device shall be checked during a weighing
operation by noting and recording the required weight, recorded weight,
and the actual mass batched. The Contractor shall confirm that the
calibration devices described in paragraph BATCH PLANT for checking the
accuracy of dispensed admixtures are operating properly.
c. Scales Corrective Action - When either the weighing accuracy or
batching accuracy does not comply with specification requirements, the
plant shall not be operated until necessary adjustments or repairs have
been made. Discrepancies in recording accuracies shall be corrected
immediately.
3.4.2.6
Batch-Plant Control
The measurement of quantities of all constituent materials batched
including cementitious materials, each size of aggregate, water, and
admixtures shall be continuously controlled. The aggregate quantities and
amount of added water shall be adjusted as necessary to compensate for free
moisture in the aggregates. The amount of air-entraining agent shall be
adjusted to control air content within specified limits. A report shall be
prepared indicating type and source of cement used, type and source of
pozzolan or slag used, amount and source of admixtures used, aggregate
source, the required aggregate and water amounts per cubic meter yard,
amount of water as free moisture in each size of aggregate, and the batch
aggregate and water amounts per cubic meter yard for each class of concrete
batched during plant operation. The report shall be submitted to the
Contracting Officer.
3.4.2.7
Concrete Mixture
a. Air Content Testing - Air content tests shall be made when test
specimens are fabricated. In addition, at least two tests for air
content shall be made on randomly selected batches of each separate
concrete mixture produced during each 8-hour period of concrete
production. Additional tests shall be made when excessive variation in
workability is reported by the placing foreman or Government quality
assurance representative. Tests shall be made in accordance with ASTM
C 231. Test results shall be plotted on control charts which shall at
all times be readily available to the Government. Copies of the
current control charts shall be kept in the field by the Contractor's
quality control representatives and results plotted as tests are made.
SECTION 03373
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