X. Lu et U. Isacsson, CHARACTERIZATION OF STYRENE-BUTADIENE-STYRENE POLYMER-MODIFIED BITUMENS - COMPARISON OF CONVENTIONAL METHODS AND DYNAMIC-MECHANICAL ANALYSES, Journal of testing and evaluation, 25(4), 1997, pp. 383-390
Rheological properties of styrene-butadiene-styrene polymer (SBS) modi
fied bitumens were studied using conventional test methods (penetratio
n, softening point, kinematic viscosity and Fraass breaking point) and
dynamic mechanical analysis (DMA). The study indicated that SBS modif
ication improved the viscoelastic properties of bitumens, which can be
demonstrated using DMA but not conventional methods. Significantly im
proved properties of binders included increased dynamic mechanical mod
uli and decreased phase angle at high temperatures, as well as reduced
complex modulus and increased phase angle at low temperatures. SBS mo
dification also caused reductions in glass transition temperature, Fra
ass breaking point, and temperature susceptibility. The degree of impr
ovement was observed to be influenced by bitumen source/grade and poly
mer content/structure. Comparison showed that certain relationships ex
ist between parameters obtained using conventional methods and DMA, su
ch as between penetration and complex modulus, kinematic viscosity and
complex viscosity, and Fraass breaking point and glass transition tem
perature. However, the main conclusion of the study is that convention
al test parameters such as penetration and softening point are not sui
table for characterization of rheological properties of SBS modified b
itumens.