Antioxidant treatment of asphalt binders

Patent metadata

Field	Value
Publication number	US-9605104-B2
Application number	US-75111710-A
Country	US
Kind code	B2
Filing date	Mar 31, 2010
Priority date	Nov 3, 2006
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

A combination of antioxidants and method of incorporating the antioxidants into an asphalt binder to make a modified asphalt binder are described. The antioxidants comprise a thioester and an aldehyde. The aldehyde and thioester, in a ratio between about 1:100 and about 100:1 parts by weight, are added to an asphalt binder. An acidic catalyst is also added in a concentration between about 0.1 wt % and about 18 wt % of the asphalt binder. The antioxidants, asphalt binder, and catalyst are mixed at a temperature between about 85° C. and about 135° C. for a time between about 30 minutes and about 6 hours. The antioxidants are capable of improving the performance grade of the asphalt binder. The modified asphalt binder possesses superior resistance to oxidative age hardening compared to other modified asphalt binder compositions that incorporate various antioxidants.

First claim

The invention claimed is:

1. A modified asphalt binder composition made by the process comprising mixing an asphalt binder, an antioxidant composition, and an acidic catalyst to create a modified asphalt binder characterized by an aging index that is lower than that of an unmodified asphalt binder;
wherein the antioxidant composition comprises an aldehyde comprising furfural in an amount of about 2 wt % and a thioester comprising dilauryl thiodipropionate in an amount of about 1.5 wt %, each based on the weight of the asphalt binder; wherein the thioester and the aldehyde are present in an effective amount capable of decreasing an aging index based on a rutting parameter at 64° C., decreasing a fatigue parameter at 25° C. and decreasing a stiffness at −12° C., each parameter measured in accordance with SUPERPAVE, of an asphalt compared to the asphalt without the thioester or the aldehyde.

2. The modified asphalt binder composition of claim 1 , wherein the aldehyde reacts with phenols in the asphalt binder to form phenolic resins, the phenolic resins comprising novolacs, resoles, or combinations thereof.

3. The modified asphalt binder composition of claim 1 , wherein the thioester is bound to the asphalt binder to allow stabilization of the thioester.

4. The modified asphalt binder composition of claim 1 , wherein the modified asphalt binder possesses at least about 50% lower flexural stiffness relative to an unmodified asphalt binder at a low temperature, the low temperature ranging from about −4° C. to about −58° C.

5. The modified asphalt binder composition of claim 1 , wherein the modified asphalt binder possesses at least about 18% higher stiffness relative to an unmodified asphalt binder at a high temperature, the high temperature ranging from about 46° C. to about 82° C.

6. The modified asphalt binder composition of claim 1 , further comprising an antistripping agent that promotes adhesion of the modified asphalt binder with a mineral aggregate.

7. An antioxidant modified asphalt binder prepared by the process comprising:
(a) heating an asphalt binder in an oxidation rich environment to a first temperature sufficient to liquefy the asphalt binder;
(b) adding an antioxidant mixture to the asphalt binder in the presence of an acidic catalyst to form the antioxidant modified asphalt binder, wherein the antioxidant mixture comprises an aldehyde comprising furfural in an amount of about 2 wt % and a thioester comprising dilauryl thiodipropionate in an amount of about 1.5 wt %, each based on the weight of the asphalt binder, and further wherein the thioester is added in a ratio of the aldehyde to the thioester that ranges between about 1:5 and about 5:1 parts by weight, and the thioester and the aldehyde are present in an effective amount capable of decreasing a rutting parameter at 64° C., decreasing a fatigue parameter at 25° C. and decreasing a stiffness at −12° C., each parameter measured in accordance with SUPERPAVE, of an asphalt compared to the asphalt without both the thioester and the aldehyde; and
(c) mixing the antioxidant modified asphalt binder at a second temperature between about 85° C. and about 135° C. blend until a predetermined stiffness of the antioxidant modified asphalt binder has been attained.

8. The antioxidant modified asphalt binder of claim 7 , further prepared by the process of:
(d) adding an antistripping agent to the antioxidant modified asphalt binder, wherein the antistripping agent promotes adhesion of the antioxidant modified asphalt binder with a mineral aggregate.

9. The antioxidant modified asphalt binder of claim 7 , wherein the first temperature is between about 80° C. and about 200° C.

10. The antioxidant modified asphalt binder of claim 7 , wherein the acidic catalyst is selected from the group consisting of sulfuric acid, toluene sulfonic acid, paratoluene sulfonic acid, ascorbic acid, phosphoric acid, and hydrochloric acid.

11. The antioxidant modified asphalt binder of claim 7 , wherein the antioxidant modified asphalt binder is characterized by an aging index that is lower than that of an untreated unmodified asphalt binder.

12. The antioxidant modified asphalt binder of claim 7 , wherein the antioxidant modified asphalt binder possesses a reduction in flexural stiffness relative to that of an unmodified asphalt binder.

13. The antioxidant modified asphalt binder of claim 7 , wherein the antioxidant modified asphalt binder possesses a higher complex shear modulus relative to that of an unmodified asphalt binder.

14. The antioxidant modified asphalt binder of claim 7 , wherein the asphalt binder is selected from the group consisting of a joint sealant, recycled asphalt pavement, emulsion, cut-back, and naturally occurring asphalt.

15. The antioxidant modified asphalt binder of claim 7 , wherein the antioxidant mixture is capable of improving the performance grade of the asphalt binder by extending the temperature range that the asphalt binder can be used within.

16. The antioxidant modified asphalt binder of claim 7 , wherein the process further comprises:
(d) coating the antioxidant modified asphalt binder onto a surface of a mineral aggregate.

Assignees

• Apeagyei Alex K
• Buttlar William G
• Dempsey Barry J
• Univ Illinois

Inventors

• Apeagyei Alex K
• Buttlar William G
• Dempsey Barry J

Classifications

• C08G16/0237 Primary

  containing sulfur · CPC title

• C08G16/0293

  with natural products, oils, bitumens, residues · CPC title

• C08L61/00

  Compositions of condensation polymers of aldehydes or ketones (with polyalcohols C08L59/00; with polynitriles C08L77/00); Compositions of derivatives of such polymers · CPC title