Going Green With Sustainable Asphalt Rap Recycling Energy & The Carbon Footprint
1. Greening the Blacktop Going Green with Sustainable Asphalt RAP, Recycling, Energy and the Carbon Footprint
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7. 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
11. 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
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21. 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.
29. 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
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.