1. 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 15 Asphalt Mix Production and Placement

2. 2 ASPHALT CONSTRUCTION

3. 3 ASPHALT Ø Has no definite chemical composition, but is almost entirely composed of a mixture of hydrogen and carbon atoms.

4. 4 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.

5. 5 ASPHALT Ø ASPHALT CEMENT GRADES: AC-2.5, AC-5, AC-10, AC-20 and AC-40 Lower numbers indicate lower viscosity and softer asphalt.

6. 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. 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. 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. 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. 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. 11 ASPHALT PAVING MATERIAL

12. 12 ASPHALT PAVING MATERIAL Asphalt layers

13. 13 COSTS Percent of Cost

14. 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. 15 PLANT SPECIFICATIONS Typical plant specifications state : Ø The mixer shall be of an approved type capable of producing a uniform mixture.

16. 16 PLANT CONTROLS Automatic production

17. 17 BATCH PLANT

18. 18 BATCH PLANT

19. 19 BATCH PLANT

20. 20 BATCH PLANT

21. 21 COLD FEED BINS

22. 22 DRYER Moisture removal Heating

23. 23 DRYER Burner unit

24. 24 DRYER Flights inside a dryer, looking toward the burner

25. 25 PUGMILL

26. 26 DRUM MIX PLANT

27. 27 DRUM MIX PLANT

28. 28 DRUM MIXER Mixing flights of a double barrel drum plant.

29. 29 AGGREGATE COLD FEED

30. 30 COLD FEED Vibrators

31. 31 HEATER Hot oil heater and liquid asphalt storage

32. 32 HOT OIL SYSTEM

33. 33 HOT LIQUID ASPHALT STORAGE

34. 34 MIX STORAGE SILO

35. 35 DUST COLLECTOR

36. 36 DUST COLLECTOR BAGS

37. 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. 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. 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.

40. 40 TO THE PROJECT