Characteristics of compound asphalt modified by waste tire rubber (WTR) and ethylene vinyl acetate (EVA): Conventional, rheological, and microstructural properties

Waste tire rubber (WTR) and waste plastic ethylene vinyl acetate (EVA) has been widely used as modifier for the improvement of asphalt individually. However, there are little studies applied the combination of WTR and EVA to the modification of asphalt to enhance its performance. This study aims to study the modifying effect of the combination of WTR and EVA on the asphalt. The conventional test and the rheological test, which including penetration test, softening point test, viscosity test, and dynamic shear rheological test were exerted to appraise the physical properties. Meanwhile, the force-ductility test and the Bending Beam Rheology test were exerted to evaluate the low-temperature performance of modified asphalt. Furthermore, the temperature and frequency sweeps were employed by using dynamic shear rheometer (DSR) to simulate the loading and temperature conditions in asphalt-based pavement mixtures. Finally, microscopy features were studied by the FTIR and environment scanning electronic microscopy (ESEM). The preliminary results of this study showed that the combination of WTR and EVA improved the high-temperature properties of the asphalt, which were manifested in reducing penetration, increasing softening point and viscosity in the laboratory. The temperature sweep results illustrated that temperature dominantly influence the elastic component at the temperature range from 30 °C to 90 °C. By combining with the rutting factor of asphalt, the fitting data of zero shear viscosity (ZSV) at 60 °C showed that with the increase of WTR or EVA content (by wt.), the resistance to rutting deformation was greatly ameliorated. FTIR results and ESEM photography identify that both WTR and EVA have perfectly mingled with asphalt. Lastly, it is concluded from the performance comparisons of the modified asphalts with different combined WTR and EVA, the optimal combination of this series of samples on high-temperature properties was 15%WTR +4%EVA.