Effect of mineral fillers adsorption on rheological and chemical properties of asphalt binder

An asphalt mastic imparts most of its characteristics to the asphalt concrete mixture and also dictates several forms of distresses in asphalt mixtures and pavements. Several studies have demonstrated that the interaction between asphalt binder and mineral fillers has a significant impact on the properties and performance of asphalt mastics and mixtures. The objective of this study was to investigate the nature of binder adsorption on mineral filler surface while simultaneously quantifying the influence of such adsorption on the properties of the binder in the immediate vicinity of the interface and bulk. An adsorption test using mineral fillers and binders was conducted to achieve this goal along with measurements of asphaltene content and rheology on the original binder and the residual binder from the adsorption tests. Results show that polar fractions preferentially adhered to the surface of the mineral filler. Such preferential adsorption resulted in a significant increase in the complex modulus of the adsorbed or fixed asphalt with a concomitant decrease in the complex modulus of the free or bulk asphalt binder. These changes in complex modulus varied only slightly as a function of the frequency. The magnitude of adsorption was dictated by the mineral nature of the surface and more importantly by the specific surface area of the particles. The findings from this study are useful to better understand and model the failure mechanisms in the micro structure of asphalt composites.