Enhancing rheological and adhesion performance of asphalt binder with alkali-activated waste dolomite dust

Asphalt modification with inorganic whiskers is a novel and green method to improve the performance of asphalt pavement, but it is still limited by the high costs and uneven dispersion of whiskers. In this study, an innovative asphalt modifier that can in-situ generate whiskers in hot mix asphalt (HMA) was developed by the alkali activation method using waste dolomite dust as raw material. The morphology and distribution of the alkali-activated waste dolomite dust (AWD) whiskers were examined by scanning electron microscopy and fluorescence microscopy, and the effects of AWD curing time, processing mode and dosage on the rheological and adhesion properties of the modified asphalt binder were evaluated. The results indicate that AWD can spontaneously form whiskers in the asphalt matrix under the flowing temperature of HMA, and the optimal performance enhancement effect on asphalt binder is achieved when the AWD curing time is 1 day, and its dosage is 5% of the asphalt binder mass. Compared with neat binder, the modified binder with AWD shows a 65% increase in rutting factor and a 2-level improvement in adhesion grade, while the costs of AWD are only 1/27 of those of commercial CaCO₃ whiskers. These findings demonstrate that AWD is a cost-effective, eco-friendly and high-performance asphalt modifier, which has great potential for application in asphalt pavement engineering.