Asphalt rubber versus other modified bitumens

Asphalt rubber and rubberized asphalt samples were produced using various
available, public recipes and their properties were compared to different laboratory and
bitumen terminal / refinery produced linear and radial type of styrene-butadiene-styrene
block copolymer (SBS), SBS-polyphosphoric acid (PPA), ethylene-vinyl-acetate (EVA) and
Elvaloy modified bitumen.
The aging characteristic of asphalt rubbers was found to be always better than the
unsaturated polymer contained modified binders, however the confidence range of standards
testing methods showed higher variability due to inhomogeneity of the rubber modified
binders. Asphalt rubber had the highest, while Elvaloy resulted the lowest viscosity at all
tested temperatures. Elasticity of SBS modified bitumens were found to be the best, while cold
performance were significantly improved by rubber modified binders due to the presence of
crumb rubber particles.
It was found that an appropriately designed and manufactured asphalt rubber binder can
replace SBS, SBS-PPA or EVA, Elvaloy modified bitumen. However it should be considered
that the main objective is probably not this but to increase utilization of rubber modified
bitumen versus common non-modified bitumen.