Sterol additive in asphalt pavement
Pavement aging can be reduced by applying to an asphalt-containing pavement a topcoat layer or a surface treatment containing asphalt binder with sterols.
1. A method of treating an existing, aged asphalt-containing pavement comprising:
providing a sterol-containing asphalt binder composition comprising an asphalt binder component and a sterol additive, wherein the sterol-containing asphalt binder composition comprises from 0.5 to 15 wt. % of the sterol additive based on the asphalt binder component;
combining the sterol-containing asphalt binder composition with aggregate to form an asphalt coating material;
applying the asphalt coating material atop the existing, aged asphalt pavement; and
compacting the applied asphalt coating material to form a coated asphalt pavement having a sterol-containing topcoat layer.
2. The method of claim 1 , wherein the asphalt coating material is applied to the existing, aged asphalt-containing pavement at a thickness in the range from about 12 mm (0.5 inches) to about 38 mm (1.5 inches).
3. The method of claim 1 , wherein the asphalt coating material is applied to the existing, aged asphalt-containing pavement at a thickness in the range from about 12 mm (0.5 inches) to about 19 (0.75 inches) mm.
4. The method of claim 1 , wherein the sterol-containing asphalt binder composition comprises 1 to 10 wt. % of the sterol additive based on the asphalt binder component weight.
5. The method of claim 1 , wherein the sterol additive comprises a pure sterol.
6. The method of claim 5 , wherein the pure sterol comprises a blend comprising a plant sterol and cholesterol.
7. The method of claim 1 , wherein the sterol additive comprises a crude sterol.
8. The method of claim 7 , wherein the crude sterol comprises a tall oil pitch.
9. The method of claim 1 , wherein the sterol additive comprises a sterol blend comprising a pure sterol and a crude sterol in a weight ratio in the range from 10:90 to 90:10 of pure sterol: crude sterol.
10. The method of claim 1 , wherein the asphalt binder component comprises recycled asphalt pavement (RAP), or recycled asphalt shingles (RAS), or a combination comprising both RAP and RAS.
11. The method of claim 1 , wherein the sterol-containing asphalt binder composition provides a ΔTc of greater than or equal to −5.0° C.
12. A coated asphalt pavement made from the method of claim 1 .
13. The method of claim 1 , wherein the sterol-containing asphalt binder composition is provided as an emulsion.
14. The method of claim 1 , wherein the sterol-containing topcoat layer comprises a micro-surfacing layer.
15. The method of claim 1 , wherein the wherein sterol-containing topcoat layer comprises a slurry seal layer.
16. The method of claim 1 , wherein the wherein sterol-containing topcoat layer comprises a chip seal layer.
17. The method of claim 1 , wherein the wherein sterol-containing topcoat layer comprises a wear layer or a cape seal.
18. The method of claim 1 , wherein the wherein sterol-containing topcoat layer comprises a fog seal layer.
19. The method of claim 1 , wherein the sterol-containing asphalt binder composition further comprises a softening agent.