Experimental Evaluation of the Properties of Asphalt Binders Modified with Calcium Sulfate Anhydrous Whiskers and Polyester Fibers

The use of waste calcium sulfate whiskers in pavement construction is cost-effective and beneficial to the environment. In this paper, modified asphalt binders are prepared by adding calcium sulfate anhydrous whiskers (ACSW, 9 wt.%,11 wt.%, and 13 wt.% by weight of asphalt binder) and polyester fibers (4 wt.%,6 wt.%, and 8 wt.% by weight of asphalt binder). The viscosity-temperature, rheological, and low-temperature properties of the modified asphalt binder were evaluated using the Brookfield rotational viscosity test, the dynamic shear rheometer (DSR) test, the bending beam rheometer (BBR) test, and the force ductility test. The results demonstrated that the addition of the ACSW and polyester fiber could improve the anti-deformation and low-temperature properties of the asphalt binders, but reduce their viscosity-temperature properties to some extent. The modified asphalt binder with 11 wt.% ACSW and 8% polyester fiber showed the best anti-deformation property, while the 11 wt.% ACSW and 6 wt.% polyester fiber modified asphalt binder had a better low-temperature performance. The force ductility test was more suitable than the BBR test to characterize the low-temperature properties of the modified asphalt binders. The Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) tests were conducted to study the functional groups and micro-structure of the modified asphalt binders, and the results indicated that no new functional groups were generated and that the interaction between the ACSW, polyester fiber, and asphalt binder was a physical adsorption and interleaving process.