06/21/07: Astec Demonstrates New Technology
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| Roadtec paver laying down the mix |
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| Invited guests take temperature reading |
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Thursday, June 21, 2007 in Chattanooga, TN, Astec, Inc. demonstrated a new process it developed to reduce the mixing and compaction temperatures of asphalt without sacrificing the quality of the resulting pavement. Astec created a system called Double Barrel® Green System to make the innovative new mix. The technology is called "green" because it has less impact on the environment than conventional asphalt mixing technology.
The new process is considered a warm mix process. However, unlike other warm mix technologies, the process developed by Astec does not require the addition of expensive commercial additives. Instead, ordinary water is injected into the mix along with the liquid asphalt cement. The injection of water causes the liquid asphalt to foam and expand in volume. The foaming action helps the liquid asphalt coat the aggregate at a temperature that is about 50°F less than traditional hot mix asphalt.
At a presentation held before the demonstration, J. Don Brock, founder and CEO of Astec Industries, Inc. highlighted the key benefits of the mix made using this technology:
- Improved Workability
-the foamed liquid asphalt coating has a lower viscosity
- No Smoke – No Smell
-the light oils in liquid asphalt never reach the boiling point, eliminating the smoke (vapor) and corresponding smell
- High Percentages of Recycle Mix with Standard Grade of Asphalt
- Longer Pavement Life
-due to less oxidation of mix and more uniformity of compaction
- 14% Less Fuel
-due to 50°F lower temperature
- 14% increase in production
Other Benefits:
- A more comfortable and safe environment for workers
- Eliminates the need for fume systems on plants and pavers
- Improved mixes
- Extends resources by using more recycle
- No increase in cost
Southeastern Materials of Chattanooga, TN created the mix using a prototype of the water injection manifold on a Double Barrel® drum mixer. The mix used during the June 21st demonstration contained 50% RAP. The mix was then transported to the paving site where Talley Construction of Chattanooga, TN used a Roadtec Shuttle Buggy® SB-2500 and RP-190 paving machine to lay 3,400 tons of the the new mix during a demonstration for invited guests. Response to the new mix was extremely positive.
During paving, mat temperatures averaged 260° behind paver, 250° at breakdown and 240° during compaction. Average compaction was 92 – well within Tennessee state specs for compaction.
Representatives from the National Center for Asphalt Technology (NCAT) were on site. NCAT obtained samples during production to conduct future tests. Testing will include wheel tracking tests, moisture susceptibility tests and total binder properties.
