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Going Green With Sustainable Asphalt   Rap Recycling Energy & The Carbon Footprint

Going Green With Sustainable Asphalt Rap Recycling Energy & The Carbon Footprint






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  • This is the concept underlying the perpetual pavement. Traffic stresses are highest near the surface of the pavement, so materials in the upper pavement layers must be resistant to rutting. The intermediate or binder courses should be comprised of rut-resistant material. Materials which have worked well include large-stone mixtures or others which provide a strong stone skeleton. Fatigue resistance is important in the lowest HMA layer or base layer. It is well documented that the most costly form of distress to fix in a pavement is bottom-up fatigue cracking. The pavement foundation serves as the ultimate support for the structure during construction and service, so it must be considered an integral part of the pavement.
  • What makes the Perpetual Pavement perpetual is that, while the surface will need periodic replacement, the bulk of the pavement structure will remain intact. Depending on the type of surface material used and the environmental conditions present, the types of distress which may arise could include top-down fatigue cracking, thermal cracking and raveling .(Click mouse to activate animated cracks.) Although surface layer lives may vary, current technology allows for achieving over 20 years, if so desired. Solutions for these distresses could include milling off the old layer and replacing it with a new surface (Click to show overlay) or simply overlaying the pavement. One advantage to this approach is that new innovations in technology can be applied to the pavement surface as they become available, possibly further extending the surface life.
  • Cross section of porous pavements. Keys are: Uncompacted subgrade, Clean large size crushed stone with high voids, thin layer of clean ½” crushed aggregate “choker course” that locks up surface to provide stable paving platform.

Going Green With Sustainable Asphalt   Rap Recycling Energy & The Carbon Footprint Going Green With Sustainable Asphalt Rap Recycling Energy & The Carbon Footprint Presentation Transcript

  • Greening the Blacktop Going Green with Sustainable Asphalt RAP, Recycling, Energy and the Carbon Footprint
  • Overview
    • Why Asphalt is sustainable
      • Perpetual Pavements
      • Carbon Footprint
      • RAP & Recycling
      • Warm Mix Asphalt
      • Porous Asphalt
      • Energy & Emission Reductions
      • Why
      • Asphalt is Sustainable
    • Sustainable Pavements
  • Sustainable Pavement
    • Durability…
      • Asphalt is the Perpetual Pavement
    • Road itself doesn’t wear out
    • Simple, fast maintenance
    • Reclaimed…is then reused
    • Total removal/reconstruction not needed
  • Sustainable Pavement
    • Requires less energy to construct an asphalt pavement
    • Per ASCE…20% less
    • Less energy consumed by public
    • Less maintenance keeps traffic moving
  • Max Tensile Strain Pavement Foundation High Modulus Rut Resistant Material (Varies As Needed) Flexible Fatigue Resistant Material 75 - 100 mm } 100 mm to 150 mm Zone Of High Compression Perpetual Pavements 40-75 mm STONE MATRIX ASPHALT, OGFC or Superpave
  • Rehabilitation { 50 - 100 mm Structure Remains Intact
    • Possible Distresses
      • Top-Down Fatigue
      • Thermal Cracking
      • Raveling
    • Solutions
      • Mill & Fill
      • Thin Overlay
    Mill Surface – Use for RAP High Quality Stone Matrix, OGFC or Superpave 20+ Years Later
      • Carbon Footprint
  • What the heck is a Carbon Footprint?
  • A carbon footprint is defined as: The total amount of greenhouse gases produced to directly and indirectly support human activities, usually expressed in equivalent tons of (CO2) Doesn’t segregate GHGs Environmental Sustainability
  • Climate Registries
    • Organizations that collect and compile emissions data generally voluntary (CA, NE US)
    • Encourages voluntary early actions to increase energy efficiency and decrease GHG emissions
  • What is a Greenhouse Gas?
    • Gases that trap heat in the atmosphere – Allows us to live here
    • Some occur from nature, others from anthropogenic activities
  • What is a Greenhouse Gas?
    • Principal greenhouse gases entering the atmosphere from human activities are:
      • Carbon dioxide (CO2)
      • Methane (CH4)
      • Nitrous Oxides (N2O)
      • Fluorinated gases (HFCs & PFCs)
  • Regulatory Concerns
    • Efforts to make you report emissions
    • Benefits of being ahead of the wave
    • Demonstrates concern for the public and the environment
  • Opportunities to Reduce Emissions
    • Sustainable Pavements
    • Warm Mix
    • RAP
    • Plant O & M
    • Truck and other equipment maintenance
      • RAP &
      • Recycling
  • Recyclability
    • Asphalt is the No. 1 recycled material
    • Biggest Re-user
    • 1995 FHWA Report to congress
      • 90 Million tons reclaimed
      • 80% recycled
    • 2006 Contractor Survey
      • ~69% reused in HMA
      • ~27% other recycling
      • <3% discarded
  • Why Recycle RAP into HMA?
    • Best and Highest use
    • Reduces demand for new materials
    • Reduces carbon footprint
    • Contains valuable materials
      • Aggregate ~95% >$10/ton
      • Asphalt ~5% > $400/ton
      • Value >$29.50/ton (minus processing)
  • Shingles
    • Shingles
      • Materials used in HMA
        • >20% asphalt binder
        • Fibers
        • Sand
      • Usually 5% of mix
        • Saves 1% binder > $6.00/ ton of HMA/WMA
      • Tear-offs
  • Over the past two years, MoDOT has allowed contractors to put used shingles that have been removed from rooftops into their asphalt mix. The result is a very durable, more-rut resistant asphalt at a much lower price. The use of recycled shingles saves $3 to $5 per ton of asphalt. That may not sound like much at first, but consider this: a typical resurfacing project would use about 30,000 tons of asphalt, for a savings of $90,000 to $150,000.
  • Other Recycled Materials
    • Crumb rubber (from tires)
    • Steel slag
    • Glass
  • Warm Mix Classifications
  • Lower Temperature Advantages
    • Lower energy consumption (≈30%)
    • Lower plant wear
    • Decreased binder aging
    • Early site opening – Return to user
    • Cool weather paving
    • Compaction aid for stiff mixes
    • Cooler working conditions
    • Porous Asphalt
  • What are Porous Pavements? Open-Graded HMA/WMA ~ 2 ½” ½” Agg. (#57) ~ 1” – 2” Thick Clean Uniformly Graded 2”-3” Crushed Agg. (#2) – 40% Voids Non-Woven Geotextile Uncompacted Subgrade
  • Porous Pavement
    • Stormwater quality improved with:
      • Porous pavement, and
      • Open Grade Friction Course
    • Can eliminate the need for stormwater structures
  • Water Quality
  • Walden Pond 1977 1997 Report: “Twenty years later, a long time for one paving job on that busy parking lot, it still looks good and works well.” 2008
    • Energy & Emission Reductions
  • Warm Mix
    • Will dominate the market in < 5 years
    • Reduced energy consumption
    • Reduced emissions
      • No hazardous fumes/worker exposure
    • Plants compatible in congested areas
    • No odors
    • The sooner the better!
  • Remedial Efforts
    • Use the components of the carbon footprint to identify problem areas
    • Take action and make adjustments to reduce emissions
    • Switch to Warm Mix sooner
    • Conduct energy audits
    • Take action to reduce energy
  • Energy Use by Road Material Type Colas Group Data
  • Reduced Energy Consumption
    • Energy Audits
    • DOE Software
    • Use RAP
    • Warm Mix Can Reduce Energy by
    • Cover the Aggregate
  • Why is Asphalt Sustainable
    • 100% Recyclable
    • Can use other recycled materials
    • Low carbon footprint pavement
    • Long life & fast resurfacing
    • Warm-Mix Asphalt
    • Porous pavement for stormwater
  • NAPA Theme
    • RAP + Porous + Warm Mix + Perpetual Pavements =
    • Sustainability
  • Summary & Review
    • Why Asphalt is sustainable
      • Perpetual Pavements
      • Carbon Footprint
      • RAP & Recycling
      • Warm Mix Asphalt
      • Porous Asphalt
      • Energy & Emission Reductions
    • Questions?