Polymer-modified, oxidized asphalt compositions and methods of preparation

Disclosed in this invention are novel road paving asphaltic compositions having improved viscoelastic properties and storage stability and unexpected phase compatibility. They contain neutralized mixtures of oxidized asphalt and an acid functionalized polymer, which polymer is selected from the group consisting of sulfonated EPDM, sulfonated styrene-butadiene, and acrylic acid terpolymers, in an amount that is sufficient to result in an asphaltic composition having a softening point greater about 55 DEG C. and a viscosity in the range from about 150 cPs to 2000 cPs or from about 3000 cPs to about 8000 cPs at 135 DEG C. and effective to allow the formation of one continuous phase or two interdispersed phases that do not segregate on standing at elevated temperatures. The basic neutralizing agent used in these compositions contain cations having a valence of from +1 to +3, preferably +2. The invention also relates to the products produced by the process and method of making the compositions. The compositions can be used as a binder in paving applications, particularly as a binder in dense graded and in open graded hot mix pavements.