ABSTRACT

Bituminous binder is always in contact with mineral fillers in asphalt mixtures, thus the mechanisms of oxidative aging of binders are influenced by the physical and chemical interaction between fillers and the bitumen. This study attempts to investigate into the factors affect the ageing process of binders. The effect of granite fillers and hydrated lime with two different bitumen binders on mastic ageing were studied. The Thin Film Oven Test (TFOT) was used for short-term aging and the Pressure Aging Vessel (PAV) used for long-term aging. Different ageing indices were used to measure the changes in physical and rheological properties such as changes in the viscosity, softening point, and complex modulus (G*) of mastics. The chemical changes of the binders were investigated by the means of Fourier Transform Infrared Spectroscopy (FTIR). Results indicate that hydrated lime slows down bitumen ageing more than granite fillers. This effect depends mainly on the bitumen type and filler concentration. Also it showed that hydrated lime interacts differently with the two binders used in this study in terms of stiffening and ageing effects. In addition results show that different ageing indices were correlated well to each other and also with the chemical changes measured by FTIR.