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 Rock the Asphalt Thinner Overlays The Right Asphalt for the Right Occasion Raise the Roof with Shingles Perpetuate Asphalt Pavements

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

RAP Guides

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 tons Reduce aggregate by 0.28 tons SAVE $8.80/ton!

AASHTO Survey of States Objectives –Find extent of RAP usage –Find the roadblocks to usage

RAP Use in Base Allowed Used

RAP Use in Binder Allowed Used

RAP Use in Surface Allowed Used

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.

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

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

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

Larger Stone Mixes

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

Issues with LSM Segregation Equipment wear Sampling Permeability Noise

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

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

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

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

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

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

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

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.

Not What We’re Looking For!

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

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

Perpetual Pavement versus Conventional Design

Comparison of Structures YearActivity 06” HMA/10” Base 15Mill 2”/Overlay 3” 2510% Patching + Mill 2”/Overlay 3” 35Reconstruct with 8” HMA 50Mill 2”/Overlay 3” YearActivity 011” HMA/6” Base 18Mill 2”/Overlay 2” 33Mill 2”/Overlay 2” 48Mill 2”/Overlay 2” Conventional Perpetual

Conventional (tons/lane-mile) Perpetual Pavement (tons/lane-mile) YearHMA*Gravel Base*HMA*Gravel Base* 02,3763,1684,3561, , , , ,188 Total9,3463,1686,7321,901 RAP2,3371,683 Aggregate6,6593,1684,7971,901 Asphalt Binder**

Material Usage Save 32% Save 28% Save 31%Save 28%

Costs Save 44%

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

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!