| Abstrakt: |
Rotational viscosities of different asphalt binders were determined at temperatures between 80°C and 185°C. Viscosity–temperature dependence of asphalt binders was described with the use of the Vogel–Tammann–Fulcher (VTF) and the William–Landel–Ferry (WLF) equations. The Vogel temperature (Tv) and the glass transition temperature (Tg) for different asphalt binders were determined by fitting experimental values of viscosity at different temperatures with these two equations. For asphalt binders, the difference between Tvand Tgwas about 40K. Effects of asphaltenes, aging, chemical modification, and polymer content on these temperatures were evaluated. As asphaltene content increased, both temperatures, Tvand Tg, increased. Different polymers showed different effects on these temperatures. The values of Tvand Tgwere correlated with the critical cracking temperature (Tcr) determined through use of a bending beam rheometer and a direct tension tester. The results suggested that the correlations between Tv, Tg, and Tcrcould be used to determine Tcrfrom the rotational viscosity results tested at high temperature. With simple rotational measurements, a quick estimation of Tcrof asphalt binders could be obtained. Liquid fragility theory was also used to study Tgof asphalt binders. Parameters determined with the VTF and WLF equations indicated that asphalt binders behaved as fragile liquids because of their non-Arrhenius behavior in the temperature range studied. |
