Methods and compositions to increase performance of asphalt cement concrete comprising recycled asphalt pavement
The Present disclosure is related to hot-mix asphalt (“HMA”) for asphalt cement concrete (“ACC”) pavement. Equivalent-performing pavement may be made at lower cost, or higher-performing pavement may be made at equivalent-to-prior-art cost. The amendments, recycled asphalt pavement (“RAP”, and including recycled asphalt shingles [“RAS”]), and reinforcing fiber (aramid fiber) may be adjusted as described herein to achieve a desired price/performance target.
1. A method of producing hot-mix asphalt (“HMA”) to form asphalt cement concrete (“ACC”) pavement, comprising:
adding recycled asphalt pavement (“RAP”) and reinforcing fiber to an aggregate to form a combined aggregate; and
adding asphalt binder and a liquid binder modifier to the combined aggregate, to form a mixture,
wherein the liquid binder modifier lowers an asphalt binder low temperature grade of the combined aggregate by at least one grade.
2. The method of claim 1 , wherein the asphalt binder includes virgin bitumen.
3. The method of claim 1 , wherein the aggregate, the RAP, the reinforcing fiber, the asphalt binder and the liquid binder modifier are evenly distributed throughout the homogenous HMA.
4. The method of claim 1 , wherein the RAP comprises recycled asphalt shingles (“RAS”).
5. The method of claim 1 , wherein a weight of the RAP is at least 10% of a weight of the combined aggregate.
6. The method of claim 1 , wherein a weight of the RAP is at least 25% of a weight of the combined aggregate.
7. The method of claim 1 , wherein a weight of the RAP is at least 38% of a weight of the combined aggregate.
8. The method of claim 1 , wherein a weight of the reinforcing fiber is between about 1 oz per ton of the homogenous HMA and about 6 oz per ton of the homogenous HMA.
9. The method of claim 1 , wherein the reinforcing fiber includes nylon, polyethylene terephthalate (PET), an aramid fiber, or a combination thereof.
10. The method of claim 1 , wherein the reinforcing fiber is coated with wax before being added to the combined aggregate.
11. The method of claim 1 , wherein the reinforcing fiber is wetted with water before being added to the combined aggregate.
12. A hot-mix asphalt (“HMA”) paving material comprising:
an aggregate including:
recycled asphalt pavement (“RAP”) including oxidized bitumen;
asphalt binder;
reinforcing fibers; and
a liquid binder modifier that lowers the asphalt binder low temperature grade of the aggregate by at least one grade.
13. The HMA paving material of claim 12 , wherein a weight of the RAP is at least 10% by weight of the aggregate.
14. The HMA paving material of claim 12 , wherein the asphalt binder includes virgin bitumen.
15. The HMA paving material of claim 12 , wherein the liquid binder modifier lowers the asphalt binder low temperature grade by at least six grades.
16. The HMA paving material of claim 12 , wherein the aggregate includes from about 1 weight percent (wt. %) to about 6 wt. % of the liquid binder modifier with respect to the weight of the aggregate.
17. The HMA paving material of claim 12 , wherein an amount of the reinforcing fibers is from about 1 oz per mix ton to about 6 oz per mix ton.
18. The HMA paving material of claim 12 , wherein the reinforcing fiber includes nylon, polyethylene terephthalate (PET), an aramid fiber, or a combination thereof.
19. The HMA paving material of claim 12 , wherein the aramid reinforcing fibers are between 10 mm and 100 mm in length.
20. The HMA paving material of claim 12 , wherein the liquid binder modifier lowers the Performance Grade (PG) of the asphalt binder from −22 to −34.