Canadian Journal of Chemical Engineering, Vol.80, No.2, 253-263, 2002
Rheological examination of temperature dependence of conventional and polymer-modified road bitumens
Rheological characterization of two types of road bitumens, conventional and polymer-modified, has been examined in the temperature range between 20degreesC and 140degreesC. Tests were carried out before and after ageing following a thin-film oven test. Polymer-modified bitumens exhibit non-Newtonian behaviour up to the 120degreesC due to a complex secondary structure formed by added polymers. For conventional bitumens, Newtonian behaviour was observed above 60degreesC. Special attention was paid to measurements and to analysis of the dynamic data of oscillatory shear. The mechanical spectra in a wide frequency range have been obtained using the WLF time-temperature superposition principle. The analysis of viscoelastic data clearly showed the differences between the two types of bitumen. Conventional bitumens were more sensitive to temperature and to the ageing effects. For polymer modified bitumens, the elastic contribution to viscoelastic response was more pronounced, and independent of temperature and ageing.