Effect of Treatment Method on the High Temperature Performance and Thermal Storage Stability of Discarded Masks Modified Asphalt

In the context of the global pandemic of covid-19, the use and disposal of medical masks have created a series of ethical and environmental issues. The purpose of this paper is to investigate and evaluate the effects of both cold and hot treatments on the high-temperature performance and thermal storage stability performance of discarded masks (DM) modified asphalt. A series of tests were conducted to evaluate the physical, rheological, and microscopic morphology properties of the samples. These tests include softening point, rotational viscosity, dynamic shear rheology, Fourier transform infrared spectroscopy, and fluorescence microscopy. The results showed that the DM modifier could improve the softening point, rotational viscosity, complex modulus, and rutting factor of the asphalt. With the same amount of modifier, the cold-treated discarded masks (CDM) modified asphalt had a higher softening point, rotational viscosity, complex modulus, and rutting factor than the heat-treated discarded masks (HDM) modified asphalt. After thermal storage, the DM modified asphalt produced segregation, and the degree of segregation was positively correlated with the amount of DM modifier. Further, the softening point, viscosity, and rutting factor of the top sample were always larger than the bottom. The difference in softening point（△TR&B）, the 135℃ rotational viscosity stability index (VS), and the 58℃ rutting factor stability index (RS) of HDM and CDM modified asphalt were 2.1℃/7.4℃, 0.53/0.995 and 0.372/1.035, respectively, when the modifier was 2%, indicating that the HDM modified asphalt had better thermal storage stability. The results of fluorescence microscopy tests of the top and bottom samples after thermal storage can illustrate the differences to some extent. In addition, the infrared spectroscopy test results showed that the HDM and CDM modified asphalt was mainly a physical co-blending process. In short, the CDM modified asphalt has better high temperature performance than the HDM modified asphalt, but taking into account the actual modification effect and thermal storage stability on the quality of modified asphalt, it is recommended to use HDM modifier with the amount of doping between 1-2%.