Innovations in Asphalt Mixtures

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Innovations in Asphalt Mixtures
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News from the Asphalt Institute

• MS-4 Asphalt Handbook, 7th edition
• National Binder Technician Certification
• Websites
• www.asphaltmagazine.com
• www.asphaltinstitute.org

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Preserving the History
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Testing for the Future

• Mixture testing focused on fatigue and E
  (Simple Performance Test)

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Public Service Announcement

• What angle are you using?

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Traffic Load Growth on Rural Interstate System
FHWA Highway Statistics 2003
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Innovations in Asphalt

• Necessity leads to invention
• Higher traffic loads pushed us to innovate
• SHRP provided funding for innovation
• What were the results?

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Lets Name SomeInnovations in Asphalt Mixtures
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Need Leads to Innovation
Need
Innovation

• Reduced tire noise safer surfaces
• Stronger more durable mixtures
• Less reflective cracking water barriers
• More environmentally friendly mixtures lower
  compaction temperatures

• OGFCs / Porous Mixtures
• SMAs
• Asphalt Interlayers
• Warm Mixtures

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Open Graded, Ultra-Thin Bonded, Porous Mixtures
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OGFCs Improve Visibility
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Ultrathin Bonded Wearing Course (UTBWC)

• lt 1 lift thickness
• Gap graded hot mix
• Placed with spray paver
• Polymer modified emulsion membrane

Overlapping membrane
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UTBWC Benefits

• Fast paving, 4-6 lane miles/day
• Quick release to traffic
• Bonds to existing
• pavement
• 4X binder vs. tack

US 281 San Antonio, TX after 12 years
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Open Mixtures Reduce Noise
Source NCHRP 284
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Porous Pavements
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Porous Pavement System
Porous Asphalt Surface (12.5 mm NMAS)
After EPA 832-F-99-023
Filter Layer (19mm NMAS)
Reservoir Layer (25mm 37.5 NMAS)
Filter Fabric
Permeable (Uncompacted?) Subgrade
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Porous Pavement Benefits

• Reduces land space consumed by conventional storm
  water detention facilities
• Reduces need for
• Curbs
• Gutters
• Inlets
• Storm sewers
• Improved wet weather skid resistance

Source Cahill Associates
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Stone Matrix Asphalt (SMA)
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ComparisonSMA and Dense Mixes
Dense Mixture
Stone Matrix Asphalt
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SMA Benefits

• Stronger than dense mixtures
• More asphalt more durable
• Less sensitive to hot temperatures

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Asphalt Interlayers

• Reflective Crack Relief Interlayer

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Interlayers Use Performance Based Specification
AASHTO T-321, at test temperatureTest
temperature determined by project climate
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Interlayer After 4 YearsIA-9 Decorah, Iowa
HMA overlay with interlayer
HMA overlay without interlayer
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Asphalt Interlayer Benefits

• Significantly delays reflective cracking
• Improving surface
• Protecting base
• Impermeable
• Protects pavement from moisture damage
• Lengthens service life of overlay

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Warm Mixtures
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Warm Mix in Practice
Evotherm Warm Mix
Hot Mix
Evotherm allows mix and compaction temperature
reductions typically around 100F.
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Warm Mix Project in Miller, Canada
2000 tons per day and after more than 2 years, no
rutting observed
Finished job
To date, performing well No longitudinal joint
issues No rutting No distresses
WMA
HMA
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Warm Mix Benefits

• Decreased emissions at the HMA plant
• Reduced worker exposure to fumes
• Savings in energy
• Extended haul distances
• Quicker return to traffic
• Easier permitting

• Improved compaction
• Lower odor
• Expanded season
• Improved thin lift capabilities
• Reduced binder requirement
• Higher RAP incorporation
• Longer binder life

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We Must Do More than Innovate

• DO Trials
• Adjust
• Implement as a standard
• Turn the innovation into a standard
• Continue to tweak
• Encourage more innovation

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Questions?