Chapter 15

Asphalt Mix Production

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Asphalt Mix Production and Placement

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ASPHALT

ØHas no definite chemical

composition, but is almost

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composition, but is almost

entirely composed of a

mixture of hydrogen and

carbon atoms.

ASPHALT

ØASPHALT CEMENT: is a

very hard, but elastic

material. It must be heated to

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material. It must be heated to

about 150º C before it

becomes fluid enough to coat

the aggregate in a paving mix.

ASPHALT

ØASPHALT CEMENT GRADES:

AC-2.5, AC-5, AC-10, AC-20

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AC-2.5, AC-5, AC-10, AC-20

and AC-40

Lower numbers indicate lower

viscosity and softer asphalt.

ASPHALT

ØASPHALT CEMENT: is a

very hard, but elastic

material. It must be heated to

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material. It must be heated to

about 150º C before it

becomes fluid enough to coat

the aggregate in a paving mix.

ASPHALT

ØCUT-BACK ASPHALT: a

mixture of asphalt cement

and a solvent such as

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and a solvent such as

naphtha or kerosene —

the asphalt has been

diluted.

ASPHALT

ØASPHALT EMULSION: a

mixture of asphalt cement

and water. Asphalt and

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and water. Asphalt and

water do not mix readily, so

an emulsifying agent is

added to keep them from

separating.

ASPHALT

ØASPHALT CONCRETE: High type asphalt paving

material used for

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material used for

construction of highways or

airfield pavements having

high traffic volumes and axle

loads.

ASPHALT

Ø ASPHALT PAVING

MATERIAL: A mixture of

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asphalt and aggregate to form

a strong, flexible, weather

resistant paving layer in a

pavement structure.

ASPHALT PAVING

MATERIAL

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ASPHALT PAVING

MATERIAL

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Asphalt

layers

20%

25%

30%

35%

40%

COSTS

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0%

5%

10%

15%

20%

QC Profit Asphalt Agg. Plant/Trk/Pave

ASPHALT PLANTS

There are approximately 3,600

active asphalt plants in the

United States. Of these, the

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United States. Of these, the

distribution is 2,300 batch

plants and 1,300 drum mix

plants.

PLANT

SPECIFICATIONS

Typical plant specifications

state:

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state:

Ø The mixer shall be of an

approved type capable of

producing a uniform

mixture.

PLANT CONTROLS

Automatic production

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BATCH

PLANT

BATCH

PLANT

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PLANT

BATCH

PLANT

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BATCH

PLANT

COLD FEED BINS

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DRYER• Moisture removal

• Heating

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DRYER

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Burner unit

DRYER Flights inside a

dryer, looking

toward the burner

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PUGMILL

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DRUM MIXPLANT

DRUM MIX

PLANT

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DRUM MIXER

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Mixing flights of a double

barrel drum plant.

AGGREGATE COLD FEED

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COLD FEED

Vibrators

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HEATER

Hot oil

heater

and

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and

liquid

asphalt

storage

HOT OIL SYSTEM

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HOT LIQUID ASPHALT STORAGE

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MIX STORAGE

SILO

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DUST COLLECTOR

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DUST COLLECTOR

BAGS

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SAFETY

Personnel working around

asphalt plants must be be safety

conscious. The potential for a

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conscious. The potential for a

serious fire results from the

presence of burner fuel for the

dryer, liquid asphalt, and hot oil

of the heat transfer system.

SAFETY

Besides the fire potential, many of

the mechanical parts are very hot.

These will cause severe burns if

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These will cause severe burns if

personnel should come into

contact with them.

SAFETY

The mechanical system for moving the

aggregates, with its belts, sprockets, and

chain drives, presents a hazard to

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chain drives, presents a hazard to

personnel if they should become

entangled in the system’s moving parts.

All of these parts should be covered or

protected, but they do require

maintenance.

TO THE PROJECT

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