Batch type hot mix plant:
Hot mixed asphalt is produced at a central plant and transported to the paving site in trucks.
An asphalt plant is a high tech group of machines, capable of uniformly blending, heating and mixing the aggregates and asphalt cement of asphalt concrete.
3. 1. Batch type hot mix plant:
• Hot mixed asphalt is produced at a central plant
and transported to the paving site in trucks.
• An asphalt plant is a high tech group of
machines, capable of uniformly blending,
heating and mixing the aggregates and asphalt
cement of asphalt concrete.
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4. Functions:
• Heating and drying the aggregates.
• Screening the aggregate into required sizes.
• Measuring the required quantity of the
aggregate, the filler and bitumen.
• Mixing the aggregate, the filler and the bitumen
in required proportion and to produce
homogeneous mix.
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6. Primary components in the order of matter flow
are:
• Cold feed system – feed belt, automatic feeder
• Cold elevator
• Drum dryer
• Hot elevator
• Asphalt handling system
• Weigh hopper
• Pug mill mixer
• Surge silo
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7. • Cold feed bins provide aggregate surge storage
and a uniform flow of properly sized material for
mixing.
• The cold feed system consists of three to six
open top bins mounted together as a single unit.
• The individual bins can be fed from sized
aggregate stockpiles by front end loader,
clamshell or conveyor.
• At the bottom of each bin is a gate for controlling
material flow.
• Belt conveyors are the most common equipment
for transporting the aggregates from the cold
bins to the drum dryer.
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8. • The purpose of a drum dryer is to heat and dry
the aggregates has been heated excessively,
the asphalt will harden during mixing.
• If the aggregates have not been heated
adequately, it is difficult to coat them completely
with asphalt.
• Every percent increase in aggregate moisture
will increase dryer fuel consumption 10%.
• The aggregate from the hot screens are stored
in the hot bins.
• Aggregate from the hot bins is dropped into a
weigh hopper situated below the bins and above
the pug mill.
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9. • To control the weighing of the blended
aggregate, the weigh hopper is charged one hot
bin at time.
• After charging the weigh hopper gates are open
to discharge the aggregate into the pug mill.
• The asphalt is pumped to the weigh tank ready
for discharging into the pug mill.
• The mixing process generally takes about 1 min
15 sec. for loading with the dry materials and 45
sec for mixing with the asphalt cement.
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10. 2. Asphalt paver:
• An asphalt paver consists of a tractor, either
track or rubber tired, and a screed.
• The tractor power unit has a receiving hopper in
the front and a system of slat conveyors to move
the mix through a tunnel under the power plant
to the rear of the tractor unit.
• At the rear of the tractor unit, the mix is
deposited on the surface to be paved.
• Angers are used to spread the asphalt evenly
across the front of the trailing screed.
• The screed controls the asphalt placement width
and thickness, and imparts the initial finish and
compaction to the hot mix material.Prof. Ashish Makwana 10
12. Advantages of paver:
• Uniform thickness of asphalt concrete is
obtained.
• The thickness of the asphalt concrete can be
changed.
• Suitable straight camber can be provided.
• Width of pavement can be increased or
decreased.
• Speed of work is faster.
• Repair and maintenance cost of the surface can
be decreased
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