Warm mix asphalt binder compositions containing lubricating additives
The present invention provides a functionally dry warm mix asphalt binder composition modified with lubricating agents or additives that can be mixed with aggregate and compacted at temperatures substantially below asphalt binder compositions that do not contain the disclosed lubricating additives.
1. An asphalt paving composition comprising functionally dry, essentially water-free, non-foamed asphalt binder containing lubricating additive comprising an ampholytic surfactant mixed with uncompacted aggregate to provide aggregate coated with binder and lubricating additive suitable for use as a warm mix paving composition; wherein the warm mix paving composition is produced at a warm mix temperature which is at least 30° F. lower than a comparison production temperature needed to produce a comparison paving composition containing binder-coated aggregate without the lubricating additive.
2. An asphalt paving composition according to claim 1 wherein the ampholytic surfactant comprises an amino acid or amino acid derivative.
3. An asphalt paving composition according to claim 1 wherein the ampholytic surfactant comprises a betain derivative.
4. An asphalt paving composition according to claim 1 wherein the ampholytic surfactant comprises an imidazoline or imidazoline derivative.
5. An asphalt paving composition according to claim 1 wherein the warm mix paving composition is paved and compacted at a warm mix temperature at least 30° F. lower than a comparison paving temperature needed for proper paving of the comparison paving composition.
6. An asphalt paving composition according to claim 5 wherein the warm mix paving composition is paved and compacted at a warm mix temperature more than 50° F. lower than the comparison production and compaction temperature.
7. An asphalt paving composition according to claim 5 wherein the warm mix paving composition is paved and compacted at a warm mix temperature more than 100° F. lower than the comparison production and compaction temperature.
8. An asphalt paving composition according to claim 1 wherein the warm mix paving composition when paved and compacted has a density 91% or higher compared to maximum theoretical density.
9. An asphalt binder composition according to claim 1 wherein the asphalt binder is a Performance Graded (PG) asphalt binder.
10. An asphalt paving composition according to claim 1 wherein the aggregate includes up to 100 weight percent reclaimed asphalt pavement (RAP).
11. An asphalt paving composition according to claim 1 wherein the asphalt binder comprises a polymer-modified, acid-modified or polymer- and acid-modified binder.
12. An asphalt paving composition according to claim 1 wherein the lubricating additive is about 0.1 to 1.5 weight percent of the asphalt binder weight.
13. An asphalt paving composition according to claim 1 wherein the lubricating additive is about 0.2 to 1.0 weight percent of the asphalt binder weight.
14. An asphalt paving composition according to claim 1 wherein a blend of the asphalt binder and lubricating additive has a measured maximum normal force no more than about 5.5 Newtons at 90° C. using a dynamic shear rheometer with a 50 μm gap.
15. An asphalt paving composition according to claim 1 wherein a blend of the asphalt binder and lubricating additive has a measured maximum normal force no more than about 3 Newtons at 90° C. using a dynamic shear rheometer with a 50 μm gap.
16. An asphalt binder composition according to claim 1 wherein the warm mix paving composition contains less than 5 wt. % water.
17. An asphalt binder composition according to claim 1 wherein the warm mix paving composition contains less than 1 wt. % water.
18. An asphalt binder composition according to claim 1 wherein the warm mix paving composition contains less than 0.5 wt. % water.