Method for modifying asphalt using oil having reduced polycyclic aromatic hydrocarbon (PAH) content obtained from the pyrolysis of waste tires

Abstract

Abstract Asphalt binders are modified using fractional products from waste tire pyrolysis, using an initial step of i) at least partially pyrolyzing, separately from such asphaltic binder, whole rubber articles or size-reduced rubber particles to provide one or more pyrolyzed rubber fractions including a pyrolyzed oil fraction having a selected minimum initial boiling point or flash point, and ii) removing some or all polycyclic aromatic hydrocarbon (P AH) compounds from such pyrolyzed oil fraction to provide a reduced-P AH and preferably translucent pyrolyzed oil fraction that may be combined with an asphaltic binder to provide a modified asphalt composition. Abstract Asphalt binders are modified using fractional products from waste tire pyrolysis, using an initial step of i) at least partially pyrolyzing, separately from such asphaltic binder, whole rubber articles or size-reduced rubber particles to provide one or more pyrolyzed rubber fractions including a pyrolyzed oil fraction having a selected minimum initial boiling point or flash point, and ii) removing some or all polycyclic aromatic hydrocarbon (PAH) compounds from such pyrolyzed oil fraction to provide a reduced-PAH and preferably translucent pyrolyzed oil fraction that may be combined with an asphaltic binder to provide a modified asphalt composition.20 25 20 04 02 21 J an 2 02 5 2 0 2 5 2 0 0 4 0 2 2 1 J a n 2 0 2 5 A b s t r a c t

Claims

1. A method for modifying an asphaltic binder, comprising the steps ofi) at least partially pyrolyzing, separately from such asphaltic binder, whole5                 rubber articles or size-reduced rubber particles to provide one or morepyrolyzed rubber fractions including a pyrolyzed oil fraction having a selected minimum initial boiling point or flash point,ii) removing at least some polycyclic aromatic hydrocarbon (PAH) compounds from such pyrolyzed oil fraction to provide a reduced-P AH10                 pyrolyzed oil fraction that may be combined with an asphaltic binder toprovide a modified asphalt composition.

2. A method according to claim 1, further comprising combining the reduced-P AH pyrolyzed oil fraction with the asphaltic binder to provide a modified asphalt composition.15   3. A method according to claim 1 or claim 2, wherein removing at least some PAHcompounds is performed by one or more of:i) fractionally distilling the pyrolyzed oil fraction over a temperature range that removes a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leaves behind at least some PAH 20                  compounds;ii) solvent extracting the pyrolyzed oil fraction using one or more solvents that remove a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leave behind at least some PAH compounds;25                   iii) centrifuging the pyrolyzed oil fraction to separate a desired initialboiling point or desired minimum flash point pyrolyzed oil fraction from a fraction containing concentrated PAH compounds; oriv) wiped film evaporating a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leaving behind at least30                  some PAH compounds.2025200402   21 Jan 20254. A method according to claim 3, wherein removing at least some PAH compounds is performed by fractionally distilling the pyrolyzed oil fraction over a temperature range.

5. A method according to claim 3 or claim 4, wherein removing at least some PAH5          compounds is performed by solvent extraction.

6. A method according to any one of claims 3 to 5, wherein removing at least some PAH compounds is performed by centrifuging.

7. A method according to any one of claims 3 to 6, wherein removing at least somePAH compounds is performed by wiped film evaporation.10   8. A method according to any one of claims 3 to 6, wherein removing at least somePAH compounds is performed by filtration of carbon solids from the pyrolyzed oil.

9. A method according to any preceding claim, wherein the total PAH content in the reduced-PAH pyrolyzed oil fraction is less than about 100 ppm by weight.

10. A method according to any preceding claim, wherein the total PAH content in the 15          reduced-PAH pyrolyzed oil fraction is less than about 10 ppm by weight.

11. A method according to any preceding claim, wherein the reduced-PAH pyrolyzed oil fraction contains less than about 10 ppm by weight total concentration of benzo(a)pyrene, benzo(e)pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene and20          dibenzo(a,h)anthracene.

12. A method according to any preceding claim, wherein the reduced-PAH pyrolyzed oil fraction contains less than about 1 ppm by weight benzo(a)pyrene.

13. A method according to any preceding claim, wherein the reduced-PAH pyrolyzed oil fraction contains less than about 5 wt. % carbon black solids.25   14. A method according to any preceding claim, wherein the reduced-PAH pyrolyzedoil fraction contains less than about 0.5 wt. % carbon black solids.2025200402   21 Jan 202515. A method according to any preceding claim, wherein the reduced-PAH pyrolyzed oil fraction is translucent.

16. A method according to any preceding claim, wherein the reduced-PAH pyrolyzed oil fraction has an open cup flash point of at least 50 °C.5   17. A method according to any preceding claim, wherein the reduced-PAH pyrolyzedoil fraction has an open cup flash point of at least 90 °C.

18. A method according to any preceding claim, wherein the reduced-PAH pyrolyzed oil fraction is combined with a lower temperature molten asphaltic binder, so that the asphaltic binder serves as a quenching agent for the pyrolyzed oil fraction.10   19. A method according to any preceding claim, wherein the reduced-PAH pyrolyzedoil fraction and one or more synthetic polymers are combined with an asphaltic binder to provide a polymer modified asphalt composition.

20. A method according to any of claims 2 to 19, further comprising using the modified asphalt composition to prepare an asphalt emulsion for use in pavement 15          construction or maintenance.

21. A method according to any of claims 2 to 20, further comprising using the modified asphalt composition for a pavement maintenance procedure comprising a) spraying onto pavement a heated liquid pavement maintenance binder comprising the modified asphalt composition; and20                 b) applying aggregate chips to the binder to provide a sealed skid resistantsurface.

22. A method according to claim 21, wherein the pavement maintenance binder has a temperature of about 250 to 325 °C.

23. A method according to claim 21, wherein the pavement maintenance binder25          comprises an asphalt emulsion having a temperature of about 4 to about 100 °C.2025200402   21 Jan 202524. A method according to any of claims 2 to 20, further comprising using the modified asphalt composition for a bituminous paving process, which process comprises:a) mixing aggregate and a modified asphalt binder containing the reduced-5                    PAH pyrolyzed oil fraction to form a bituminous mix comprising theaggregate coated with the modified asphalt binder; andb) compacting the bituminous mix to provide bituminous pavement having field density values of less than 10% in place air voids for the compacted bituminous mix.10   25.    A modified asphalt binder made according to any of claims 2 to 20 and containingreduced-PAH pyrolyzed oil.

26. An asphalt paving mixture containing a modified asphalt binder made according to claim 25.

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