Method of making sulfur extended asphalt modified with crumb rubber
The present invention relates to asphalt compositions. The present invention provides for a sulfur rubber asphalt binder composition that includes a base asphalt having a softening point, elemental sulfur, and a crumb rubber material. The crumb rubber material is combined with the base asphalt and the elemental sulfur to create the sulfur rubber asphalt binder composition. The crumb rubber material is present in the sulfur rubber asphalt binder in an amount effective to increase the softening point as compared to the softening point of the base asphalt.
1. A method of making a sulfur rubber asphalt binder composition comprising the steps of:
mixing a crumb rubber material with a base asphalt at a first temperature in a high shear blender for first amount of time to create an asphalt crumb rubber mixture;
maintaining the asphalt crumb rubber mixture in a sealed container in an oven at the first temperature for a second amount of time to create an aged asphalt crumb rubber mixture; and
introducing elemental sulfur to the aged asphalt crumb rubber mixture and mixing for a third amount of time at a second temperature such that the sulfur rubber asphalt binder composition forms;
where the asphalt is about 58 weight percent, the elemental sulfur is about 40 weight percent and the crumb rubber material is about 2 weight percent, each by weight of the sulfur rubber asphalt binder composition.
2. The method of claim 1 , where the sulfur rubber asphalt binder composition and the base asphalt each have a softening point temperature, and the softening point temperature for the sulfur rubber asphalt binder composition is greater than that of the base asphalt.
3. The method of claim 1 , where the sulfur rubber asphalt binder composition and the base asphalt each have a penetration grade value, and the penetration grade value for the sulfur rubber asphalt hinder composition is less than that of the base asphalt.
4. The method of claim 1 , where the sulfur rubber asphalt binder composition and the base asphalt each have a Performance Grade temperature range, and the Performance Grade temperature range for the sulfur rubber asphalt binder composition is broader than that of the base asphalt.
5. The method of claim 1 ; where the Performance Grade temperature range of the sulfur rubber asphalt binder composition is 76-10.
6. The method of claim 1 , where the sulfur rubber asphalt binder composition and the base asphalt each have a set of complex modulus (G*) values associated with a range of temperature values from 67° C. to 79° C., and where each G* value for the sulfur rubber asphalt binder composition is greater at each temperature value within the range of temperature than that of the base asphalt.
7. A method of making a sulfur rubber asphalt binder composition comprising the steps of:
mixing a crumb rubber material with a base asphalt at a first temperature in a high shear blender for a first amount of time to create an asphalt crumb rubber mixture; maintaining the asphalt crumb rubber mixture in a sealed container in an oven at the first temperature for a second amount of time to create an aged asphalt crumb rubber mixture; and
introducing elemental sulfur to the aged asphalt crumb rubber mixture and mixing for a third amount of time at a second temperature such that the sulfur rubber asphalt binder composition forms;
where the elemental sulfur is in a range of from about 30 to about 50 weight percent and the crumb rubber material is in a range of from about 1 to about 6 weight percent, each by the weight of the sulfur rubber asphalt binder composition; and
where the first temperature is in the range of 170-190° C. and the second temperature is in the range of 140-150° C.
8. The method of claim 7 , wherein the elemental sulfur is in powder form.
9. The method of claim 7 , where the elemental sulfur is in liquid form.
10. The method of claim 7 , where the first temperature is about 180° C.
11. The method of claim 7 , where the second temperature is about 145° C.
12. The method of claim 7 , where the first amount of time is about 2 minutes.
13. The method of claim 7 , where the second amount of time is about 2 hours.
14. The method of claim 7 , where the third amount of time is about 20 minutes.
15. The method of claim 7 , where the asphalt is about 58 weight percent, the elemental sulfur is about 40 weight percent and the crumb rubber material is about 2 weight percent, each by weight of the sulfur rubber asphalt binder composition.