Crack Reducing Interlayer:
Asphalt-rubber SAMIs (Stress Absorbing Membrane Interlayers) are placed between distressed pavements and hot mix overlays to seal existing cracks and retard reflective cracking. The innovative interlayer includes 3/8” or 1/2” stone placed over a thick (0.5 to 0.7 gallons per yd2) hot-applied binder composed of asphalt blended with 20% by weight rubber from recycled tires. The interlayer is then covered with a traditional hot mix asphalt overlay. The tire rubber is finely ground at ambient temperatures then blended with asphalt at temperatures exceeding 350ºF. The high temperature causes the oils in the asphalt to swell the elastomeric rubber polymer, resulting in a stiff, elastic and flexible binder material that remains flexible at low temperatures and doesn’t flow at high temperatures. The tire rubber contributes polymer, carbon black and anti-oxidants. The result is a thick, very adhesive and cohesive membrane binder that bridges and flexes with cracks, protects the pavement structure from water and retards reflective cracking. The asphalt-rubber SAMI extends the life of overlays.
Benefits of Asphalt-Rubber SAMIs
- Retards reflective cracking
- Waterproofs and seals cracks and imperfections on the old pavement surface
- Flexes with the pavement even at temperature extremes
- Uses recycled material
- Quick construction and traffic return with minimal user delays
- With the right hot mix overlay, adds structure, improves rideability and smoothness, allows thinner lifts
- Long lasting corrective maintenance for improving rideability and extending the life of your pavements
The SAMI Process
All States Materials Group’s asphalt rubber is formulated for durability and adhesiveness. It is manufactured at our facility with strict quality control for consistency and performance. We use coated and heat-treated high quality stone that has been tested for shape, hardness, proper gradation and cleanliness. A laboratory design with the project materials determines the correct asphalt rubber and aggregate application rates. There should be sufficient asphalt to give the proper interlayer membrane thickness, and just enough aggregate to cover the asphalt rubber (typically 30 to 35 pounds per yd2). After any repairs are made and the pavement is cleaned of any loose debris, a properly adjusted and calibrated distributor truck sprays the hot asphalt rubber on the pavement at the predetermined shot rate. This is immediately covered by the aggregate applied by a continuous, self-propelled aggregate spreader. The interlayer is then rolled to properly orient and seat the aggregate. The finished SAMI is ready for the hot mix overlay.
Where and When to Use Asphalt-Rubber SAMIs
Asphalt-rubber SAMIs are designed for waterproofing and sealing the existing distressed pavement surface and retarding reflective cracking when overlaying severely cracked and raveled surfaces. It has been proven effective on streets, highways and airfields. The pavement to be overlaid should have a structurally sound base and be properly drained. It may have aged asphalt with extensive surface cracking, raveling and other surface distresses. There should be no sign of sub-base movements or moisture damage. When warranted, potholes and large cracks should be filled. The surface should be swept of any stones, sand, mud or other loose debris. With the right hot mix overlay, asphalt-rubber SAMIs enable thinner overlay lifts and retard reflective cracking, extending the serviceable life of the overlay.
All States Materials Group wants to make sure your paving job is a success. Our professionals can work with municipal, state or consulting engineers on a job-by-job basis to construct an asphalt-rubber SAMI or hot mix that meets your specific needs. We can help with such issues as equipment rentals and aggregate supply as well as our superior quality complete turnkey contracting. We will be there to make sure you are satisfied. Contact us for more information about asphalt-rubber SAMIs.