Effects of mixing procedures on the properties of polymer modified bitumen

Abstract

In this study two types of polymer pellets, Styrene-Butadiene-Styrene (SBS)
and Ethylene Vinyl Acetate (EVA), were used to modify a 70/100 pen grade bitumen.
Mixing variables such as, mixing speeds, mixing times and maturation times were considered
in the polymer modification process. The influences of the mixing variables on the polymer
modified binder were evaluated using conventional binder test methods and morphology
study using florescence microscopy. The microscopy and conventional binder test result
analysis in general showed the strong influence of mixing speed on polymer dispersion. The
effects of mixing times on the binder test results were not distinct for both EVA and SBS
polymers. The effect of pre/post stirring procedures on the binder test results was also found
minimal, only the maximum speed used in the maturation process seem to influence the test
results.