Moisture sorption can significantly influence hydrothermal ageing and alter the chemical and rheological properties of bituminous mastics. Mineral filler particles are added to bituminous binders to form mastics with increased stiffness. The addition of fillers can considerably change the moisture sorption and the physico-chemical properties of binders by surface interactions and physical presence. This study aims to investigate the effect of filler type on the moisture-induced changes of bituminous mastics after wetting-drying cycles by means of sorption, rheological and infrared spectrometry tests. The results show that mineral fillers with higher diffusivity increase the overall capacity of mastics to absorb moisture, but at the same time allow for moisture desorption during drying. Nevertheless, it has been found that it is not the diffusivity properties but rather the bitumen and filler interactions that control the hydrothermal ageing of the mastics.

Bitumen undergoes ageing, which leads to changes in its chemical and rheological properties, causing it to become harder and more brittle with time. This study aims to compare the effects of different laboratory ageing methods on the chemistry and rheology of three bitumen types: a Pen 40=60, a Pen 70=100, and a polymer-modified bitumen (PmB). Four ageing protocols were applied: ageing at room temperature, oven ageing, pressure ageing vessel (PAV), and rolling thin-film oven test (RTFOT) combined with PAVageing. The effects of temperature, pressure, and ageing time were studied using dynamic shear tests and infrared spectroscopy. The results highlight the relationship between chemistry and rheology of bitumen. Bitumen hardening, which was revealed by an increase in complex modulus and a decrease in phase angle, was reflected in the growth of specific chemical functional groups. Among all materials, soft bitumen showed the greater tendency to oxidize. Different behavior was observed for PmB, which presented the highest resistance against oxidation among the studied bitumens, even though the reaction with oxygen caused the deterioration of the added polymer modifiers.