Effect of active mineral or hydrated lime fillers on ageing and moisture of bituminous mixtures

This thesis attempts to provide a deeper understanding of the effect of mineral fillers on the aging of bitumen with and without the presence of moisture in the mixture. More specifically, a chemical and mechanical performance characterization of mineral fillers containing hydrated lime was carried out, deepening the issue of degradation and carbonation in limestone following oxidative aging. Six different mineral fillers have been used in this research; the fillers differed with respect to the amount of active hydrated lime. The mixtures of bitumen-mineral fillers were prepared according to a single design protocol. The resulting mastics together with the neat bitumen were subjected to accelerated aging in the laboratory by means of the Pressure Aging Vessel (PAV). The ageing protocols differed with regard to the gas that was used and the presence of humidity. After each conditioning protocol, the samples were tested by using Dynamic Shear Rheometer (DSR) and Fourier Transfer Infrared spectrometer (FTIR). DSR was used to determine the rheological properties of materials, such as relaxation, fatigue and stiffness. FTIR was used to study the chemical composition of fillers and mastics before and after conditioning. The FTIR measurements were further used to develop a methodology that enables the quantification of the degradation of hydrated lime due to moisture and ageing effects.