Saving Your Asphalt

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Saving YourAsphalt!
36th Annual Rocky Mountain Asphalt Conference
Equipment Show February 18-20, 2009
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The Bad News
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The Good News
Lets not get caught off-guard next time!
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The Bad News
Natural Disasters
Unnatural Disasters
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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

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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

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RAP Guides
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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!

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AASHTO Survey of States

• Objectives
• Find extent of RAP usage
• Find the roadblocks to usage

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RAP Use in Base
Allowed
Used
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RAP Use in Binder
Allowed
Used
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RAP Use in Surface
Allowed
Used
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The Survey Says. . .

• We can do more recycling under the existing
  specs. Need to consider how its handled.
• Need to consider availability.
• Not much consistency between states on whats
  allowed.
• We need to work with agencies to get RAP
  percentages increased, especially in surface
  mixes.

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What is limiting RAP?

• Specification limits Superpave
• Specification limits surface
• Lack of knowledge by specifiers
• Specification limits PMA
• Binder Issues

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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

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Surface Area
10 Cube of 1/2 Balls Surface Area 6,280 in2
10 Cube of 1 Balls Surface Area 3,142 in2
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10
10
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Larger Stone Mixes
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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!

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Issues with LSM

• Segregation
• Equipment wear
• Sampling
• Permeability
• Noise

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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

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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 _at_ 75/ton
• For 9.5 mm mix 37.5 mm
• AC content 6.5
• 163 lbs/sy 6.93/sy _at_ 85/ton
• Thinner overlay 18 less asphalt
• Thinner overlay 1.21/sy less

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When not to use Thin Overlays

• When large NMAS is specified.
• When structural improvement is needed.

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Dont 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

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PMA Economics

• Can be 60 to 80/ton higher than unmodified
  asphalt
• Can raise HMA price by 4.80/ton

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Raise the Roof with Shingles

• Roofing shingles comprised of
• Polymer modified asphalt
• Fiberglass or felt fibers
• Grit angular fine aggregate
• Mineral filler

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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

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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.

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Not What Were Looking For!
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Perpetual Pavements

• The sixth of five ways to save asphalt!
• Save asphalt and aggregate over the long term.
  Its sustainable.
• Lower Life Cycle Cost
• Lower User Cost

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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
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Perpetual PavementversusConventional Design
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Comparison of Structures
Perpetual
Conventional
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Material Usage
Save 31
Save 28
Save 28
Save 32
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Costs
Save 44
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Summary

• Possible to save both asphalt and aggregate.
• Need to apply proper solutions.
• Need to apply engineering principles.
• DONT SACRIFICE QUALITY!

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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!