Effect of filler properties on the hydrothermal ageing of bituminous mastics

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.