Low temperature preparation of rubber-modified asphalt cement
This invention encompasses systems, methods, and apparatuses for low temperature preparation of rubber modified asphalt cement as well as resulting compositions.
1. A method for preparing a rubber-modified asphalt cement composition, comprising:
i) contacting asphalt with rubber granules to form a mixture;
ii) heating the mixture to a temperature in the range of 450° F. to 510° F. to form a heated mixture;
iii) mixing at least a portion of the heated mixture with rubber granules in a pre-wet vessel comprising a mixer to form a heated wetted asphalt/rubber mixture; and
iv) passing the heated wetted asphalt/rubber mixture through at least one high shear mixer, wherein the rubber-modified asphalt cement composition has an integration value of at least 90.
2. The method of claim 1 , wherein the temperature is in the range of 460° F. to 510° F.
3. The method of claim 1 , wherein the temperature is in the range of 480° F. to 510° F.
4. The method of claim 1 , wherein the temperature is in the range of 490° F. to 510° F.
5. The method of claim 1 , wherein the rubber-modified asphalt cement composition has a rubber content in the range of 5-35 wt. % relative to the total weight of the rubber-modified asphalt cement composition.
6. The method of claim 1 , wherein the rubber-modified asphalt cement composition has a rubber content in the range of 5-15 wt. % relative to the total weight of the rubber-modified asphalt cement composition.
7. The method of claim 1 , wherein the rubber-modified asphalt cement composition has a rubber content of greater than 18 wt. % relative to the total weight of the rubber-modified asphalt cement composition.
8. The method of claim 1 , wherein the rubber-modified asphalt cement composition is a rubber-modified asphalt cement concentrate.
9. A system for preparing a rubber-modified asphalt cement composition, comprising:
i) an asphalt charging device for charging asphalt into the system;
ii) a rubber charging device for charging rubber granules into the system;
iii) at least one heater for heating the charged asphalt, the charged rubber granules, or a mixture thereof to a temperature in the range of 450° F. to 510° F.;
iv) at least one pre-wet vessel comprising a mixer to form a wetted asphalt/rubber mixture from the charged asphalt and charged rubber granules;
v) at least one high shear mixer for mixing the wetted asphalt/rubber mixture into the rubber-modified asphalt cement composition; and
vi) a controller for controlling the asphalt charging device, the rubber charging device, and/or the at least one high shear mixer, in a manner such that the rubber-modified asphalt cement composition has an integration value of at least 95.
10. The system of claim 9 , wherein the temperature is in the range of 460° F. to 510° F.
11. The system of claim 9 , wherein the temperature is in the range of 480° F. to 510° F.
12. The system of claim 9 , wherein the temperature is in the range of 490° F. to 510° F.
13. The system of claim 9 , wherein the rubber-modified asphalt cement composition comprises 5-15 wt. % rubber.