Asphalt-rubber compositions and systems and methods for preparing same

Abstract

One embodiment provides a process for preparing an asphalt-coated crumb rubber composition that meets the specification set forth in ASTM D80-02 or deviations thereof which may be established by the specifying agency from time to time. The process generally comprises obtaining asphalt of different penetration grades, combining the asphalt of each grade with preselected chemicals to form separate premixed components, blending the premixed components together under predetermined conditions to form, upon curing, an asphalt-coated crumb rubber composition that meets certain physical requirements for asphalt-rubber binder (ARB), such as those set forth in ASTM D8-02. Advantageously, the resulting asphalt-coated crumb rubber composition not only meets the physical requirements of ARB used in road paving but also has improved dispersion of the rubber, such as dispersion of the rubber in an oil-in-water emulsion of an asphalt.

What is claimed is: 
     
         1 . An emulsion of an asphalt-rubber binder comprising:
 an asphalt;   crumb rubber, representing about 30% to about 50% of the total weight of all non-volatile components of the emulsion, which has swollen in the presence of the asphalt;   a cationic surfactant;   and water;   wherein the emulsion is stable at a pH below about 7.   
     
     
         2 . An asphalt emulsion comprising:
 an asphalt having a pen value of from about 0 dmm to about 30 dmm;   an amido amine surfactant, an ammonium salt thereof, or a combination thereof; and   water, representing about 30% to about 50% of the weight of the emulsion.