6 ASPHALT Ø ASPHALT CEMENT : is a very hard, but elastic material. It must be heated to about 150º C before it becomes fluid enough to coat the aggregate in a paving mix.
7 ASPHALT Ø CUT-BACK ASPHALT : a mixture of asphalt cement and a solvent such as naphtha or kerosene — the asphalt has been diluted.
8 ASPHALT Ø ASPHALT EMULSION : a mixture of asphalt cement and water. Asphalt and water do not mix readily, so an emulsifying agent is added to keep them from separating.
9 ASPHALT Ø ASPHALT CONCRETE : High type asphalt paving material used for construction of highways or airfield pavements having high traffic volumes and axle loads.
10 ASPHALT Ø ASPHALT PAVING MATERIAL : A mixture of asphalt and aggregate to form a strong, flexible, weather resistant paving layer in a pavement structure.
11 ASPHALT PAVING MATERIAL
12 ASPHALT PAVING MATERIAL Asphalt layers
13 COSTS Percent of Cost
14 ASPHALT PLANTS There are approximately 3,600 active asphalt plants in the United States. Of these, the distribution is 2,300 batch plants and 1,300 drum mix plants.
15 PLANT SPECIFICATIONS Typical plant specifications state : Ø The mixer shall be of an approved type capable of producing a uniform mixture.
16 PLANT CONTROLS Automatic production
17 BATCH PLANT
18 BATCH PLANT
19 BATCH PLANT
20 BATCH PLANT
21 COLD FEED BINS
22 DRYER Moisture removal Heating
23 DRYER Burner unit
24 DRYER Flights inside a dryer, looking toward the burner
26 DRUM MIX PLANT
27 DRUM MIX PLANT
28 DRUM MIXER Mixing flights of a double barrel drum plant.
29 AGGREGATE COLD FEED
30 COLD FEED Vibrators
31 HEATER Hot oil heater and liquid asphalt storage
32 HOT OIL SYSTEM
33 HOT LIQUID ASPHALT STORAGE
34 MIX STORAGE SILO
35 DUST COLLECTOR
36 DUST COLLECTOR BAGS
37 SAFETY Personnel working around asphalt plants must be be safety 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.
38 SAFETY Besides the fire potential, many of the mechanical parts are very hot. These will cause severe burns if personnel should come into contact with them.
39 SAFETY The mechanical system for moving the aggregates, with its belts, sprockets, and 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.