Evaluation of asphalt mixtures modified with polymer and wax

Performance of bitumen is significantly susceptible to the environmental changes and traffic loading characteristics. Thus, different types of asphalt additives may improve the bitumen performance under these conditions. In this paper, the rheological properties of a conventional asphalt binder (typically used in Egypt) modified with different polymer products and wax were investigated. The modifiers are SUPERPLAST, Showax, waste plastic bags and polypropylene polymer. Penetration, softening point, rotational viscometer tests and scanning electron microscopy (SEM) were performed on the conventional and modified binders. Conventional and modified mixtures were prepared and tested for Marshall stability, and the optimum percentage of each modifier was determined. The moisture susceptibility of the asphalt mixtures was evaluated in terms of indirect tensile strength (IDT) and loss of stability. The dynamic modulus (E*) of the asphalt mixes was estimated by some of the popular predictive equations for the prediction of pavement performance using the quality-related specifications software (QRSS) at two different rates of loading (traffic speed) and three climatic conditions in Egypt. The results showed better mechanical properties and better resistance to moisture damage for the modified mixtures. In general, the findings indicate that the use of polymer products or wax as modifiers is helpful in improving the pavement performance.