LABORATORY STUDIES OF BITUMEN REJUVENATOR DIFFUSION USING FTIR-ATR

The topic of this thesis originates from the lack of knowledge regarding the diffusion process by which new and old binders are mixed. If the process is incomplete, the properties of the final recycled asphalt will be influenced negatively. A new method using FTIR-ATR (Fourier Transform Infrared Spectroscopy by Attenuated Total Reflectance) has been developed to characterise the diffusion of one bituminous binder into another. Using this method, a study has been made of parameters such as temperature, binder film thickness, degree of ageing (TFOT), and, to some extent, chemical properties of the binders. The results show that temperature has a major influenc on the diffusion rate, while the effect of ageing appears to be negligible. It is also shown that the diffusion process can be described using Ficks law. Generally, the diffusion rate is influenced by temperature, the size of the diffusing molecules and the viscosity of the media in which the diffusion takes place. The results imply that it is the viscosity of themaltene phase of the binder that governs the diffusion rate rather than the viscosity of the bitumen as a whole. (A)