testing, in accordance with paragraph TESTS AND INSPECTION, will be
performed by the government near the end of this trial operation
period. The Contractor shall notify the Contracting Officer of the
trial operation not less than 7 days prior to the start of the trial
operation.
m. Protection - The weighing, indicating, recording, and control
equipment shall be protected against exposure to dust, moisture, and
vibration so that there is no interference with proper operation of the
equipment.
3.1.2.4
Continuous Mixing Plant(s)
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NOTE: See the concrete materials DM or consult the
materials engineer to fill in the blanks.
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A continuous mixing plant(s) shall be capable of producing RCC of the same
quality and uniformity as would be produced in a conventional batch plant
and shall be capable of producing a uniform continuous product (at both
maximum and minimum production rates) that is mixed so that complete
intermingling of all ingredients occurs without balling, segregation, and
wet or dry portions.
a. Operation and Accuracy - An electronic control system shall be
provided. The control system shall have the capability of changing
mixtures instantaneously, producing at least [_____] different
mixtures, producing any of the mixtures at a variable rate, and
tracking a mixture change to a hopper or a conveyor system. The
control panel shall display for each ingredient the designed formula
values and the instantaneous percentage values and shall record the
instantaneous values at a preset time interval or on demand with a
multiple copy printer/recorder. The recorder shall note formula
changes and shall print total quantities of each ingredient and total
amounts produced on command. There shall be weighing devices (belt
scale or other) for continuous weighing of individual ingredients and
total ingredients. The plant control shall not require manual devices
to adjust the material flow. The plant shall be capable of total
manual control operation for a single product at a limited production
for short-time durations in the event of loss of electronic control.
The electronic control system shall incorporate modular replaceable
components to reduce down time in the event of control system
malfunction. An inventory shall be maintained of such replaceable
components. The fine aggregate shall have a device that monitors its
content immediately prior to dispensing into the mixing plant
dispensing system. The accuracy of the plant dispensing systems shall
be within the following limits:
Pozzolan ...................................... 0 to +2
percent
Cement ........................................ 0 to +2
percent
Water ............................................. 1
percent
Aggregate smaller than
37.5 mm (1-1/2 in.) size ........................ 2
percent
Aggregate larger than
37.5 mm (1-1/2 in.) size ........................ 3
percent
Admixtures .................................... 0 to +6
percent
Note: The continuous feeders for each of the ingredients shall be calibrated
SECTION 03701
Page 35
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