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Saving Your Asphalt!

Saving Your Asphalt!. 36 th Annual Rocky Mountain Asphalt Conference & Equipment Show February 18-20, 2009. The Bad News. The “Good” News. Let’s not get caught off-guard next time!. The “Bad” News. Natural Disasters. Unnatural Disasters. Five Ways to Save Your Asphalt. Up the RAP

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Saving Your Asphalt!

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  1. Saving YourAsphalt! 36th Annual Rocky Mountain Asphalt Conference & Equipment Show February 18-20, 2009

  2. The Bad News

  3. The “Good” News Let’s not get caught off-guard next time!

  4. The “Bad” News Natural Disasters Unnatural Disasters

  5. Five Ways to Save Your Asphalt • Up the RAP • Rock the Asphalt • Thinner Overlays • The Right Asphalt for the Right Occasion • Raise the Roof with Shingles • Perpetuate Asphalt Pavements

  6. Up the RAP • Reuse what you have. • Characterize it like it was any other component of your product. • Process it properly. • Advantages • Economics • Environment • Performance

  7. RAP Guides

  8. RAP Example • Virgin mix requires 5.5% AC • RAP has 4.0% AC • Use 30% RAP – Reduce virgin AC 1.2% • RAP Processing - $6.00/ton • AC price $650/ton – Aggr. price $10/ton • On 1 ton HMA reduce AC by 0.012 tons • Reduce aggregate by 0.28 tons • SAVE $8.80/ton!

  9. AASHTO Survey of States • Objectives • Find extent of RAP usage • Find the roadblocks to usage

  10. RAP Use in Base Allowed Used

  11. RAP Use in Binder Allowed Used

  12. RAP Use in Surface Allowed Used

  13. The Survey Says. . . • We can do more recycling under the existing specs. Need to consider how it’s handled. • Need to consider availability. • Not much consistency between states on what’s allowed. • We need to work with agencies to get RAP percentages increased, especially in surface mixes.

  14. What is limiting RAP? • Specification limits Superpave • Specification limits surface • Lack of knowledge by specifiers • Specification limits PMA • Binder Issues

  15. Rock the Asphalt! • Use Large Stone Mixes where possible. • Larger aggregate mixes need less asphalt to provide the same coating. • Applications • Heavy duty pavements • Base mixes

  16. Surface Area 10” Cube of 1/2” Balls Surface Area = 6,280 in2 10” Cube of 1” Balls Surface Area = 3,142 in2 10” 10” 10” 10” 10” 10”

  17. Larger Stone Mixes

  18. Large Stone Example • Compare 1-3/4” mix to 5/8” mix • LSM uses 1.7% less asphalt • Save 0.017 tons AC per ton HMA • Save $11.05 per ton HMA!

  19. Issues with LSM • Segregation • Equipment wear • Sampling • Permeability • Noise

  20. Thinner Overlays • If overlay placed to correct functional deficiency (smoothness) rather than structural, consider a thinner overlay. • Lift thickness related to aggregate size. • Fine aggregate mixes do not rut more than coarse aggregate mixes. – NCHRP Report 539

  21. Thin Overlay Example • Say NMAS/lift is 4 • For 12.5 mm mix ~ 50 mm • AC content 6.0% • 217 lbs/sy = $8.14/sy @ $75/ton • For 9.5 mm mix ~ 37.5 mm • AC content 6.5% • 163 lbs/sy = $6.93/sy @ $85/ton • Thinner overlay = 18% less asphalt • Thinner overlay = $1.21/sy less

  22. When not to use Thin Overlays • When large NMAS is specified. • When structural improvement is needed.

  23. Don’t Be Gauche – Use the Right Asphalt • Polymer modified asphalt has many uses: • Reduce rutting • Reduce thermal cracking • Reduce fatigue cracking • Improve overall durability • Can also be misused: • Low volume roads • Overlays of cracked pavements • Base layers

  24. PMA Economics • Can be $60 to $80/ton higher than unmodified asphalt • Can raise HMA price by $4.80/ton

  25. Raise the Roof with Shingles • Roofing shingles comprised of: • Polymer modified asphalt • Fiberglass or felt fibers • Grit – angular fine aggregate • Mineral filler

  26. Example • Roofing shingles contain ~ 20% asphalt • Use 5% shingles in HMA, reduce 1% asphalt • Reduce 0.01 ton AC/ton HMA • Reduce cost by $6.50/ton HMA

  27. Issues with Shingles • Tear-off shingles require more processing than manufacturing waste. • Be careful using tear-offs and RAP in same mix. Make sure there is enough virgin asphalt. • Sizing of shingle particles is important – should be minus ½ inch.

  28. Not What We’re Looking For!

  29. Perpetual Pavements • The sixth of five ways to save asphalt! • Save asphalt and aggregate over the long term. It’s sustainable. • Lower Life Cycle Cost • Lower User Cost

  30. Concept } 40-75 mm SMA, OGFC or Superpave 100 mm to 150 mm Zone Of High Compression High Modulus Rut Resistant Material (Varies As Needed) Flexible Fatigue Resistant Material 75 - 100 mm Max Tensile Strain Pavement Foundation

  31. Perpetual PavementversusConventional Design

  32. Comparison of Structures Perpetual Conventional

  33. Material Usage Save 31% Save 28% Save 28% Save 32%

  34. Costs Save 44%

  35. Summary • Possible to save both asphalt and aggregate. • Need to apply proper solutions. • Need to apply engineering principles. • DON’T SACRIFICE QUALITY!

  36. Other Ideas • Get Pavement considered as part of solution to road noise – Lower Noise Barriers by 3 ft! • Use Rubblization with Overlay rather than Remove and Replace PCC – Save 60 to 70% of Total Cost!

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