THE IMPACT OF AGEING ON THE BITUMEN STIFFNESS MODULUS USING THE CAM MODEL

This article presents the results of the viscoelastic properties of the polymer-modified bitumen produced in Warm Mix Asphalt technology. A Fischer-Tropsch synthetic wax and a liquid surface-active agent (fatty amine) were used as bitumen viscosity-reducing modifiers. All tested parameters were determined after short-term and long-term ageing. The complex modulus G* and phase angle delta were measured with a cone-plate rheometer. All dynamic tests were performed at 60 degrees C within the frequency range from 0.005 Hz to 10 Hz. On the basis of the rheological index R determined using the Christensen-Anderson-Marasteanu (CAM) model, it was found that the fatty amine additive slowed down the agehardening process in the bitumen. In contrast, the synthetic wax increased the stiffness of the bitumen at all levels tested, regardless of the type of ageing simulation process.