No abstract

The polyurea elastomer (PUA) powder modifier was prepared by the method of spraying–initial crushing–fine grinding, and then, the PUA-modified asphalt was produced. The typical functional structure of PUA was identified and characterized. The apparent viscosity of PUA-modified asphalt was tested at different temperatures. The impact of particle size and content of PUA on creep and recovery properties of asphalt at high temperature was investigated through the multiple stress creep recovery test. The mesothermal fatigue behavior of PUA-modified asphalt was evaluated by means of time sweep and linear amplitude sweep. Results indicated that the high elastic properties of PUA materials might depend on the spherical structure inside PUA material. The diameter of functional structure was around 20 µm and presented as 3D ball structure. The increase in PUA particle size would lead to the increase in cracks and folds in the bonding surface PUA modifier could improve by about 50% of the apparent viscosity significantly. Furthermore, PUA modifier could promote the high-temperature rutting resistance and middle-temperature fatigue property of asphalt. The improving effect on R could reach almost 28% and the 0.075 mm could be the best application size of PUA.

In order to investigate the effect of nano polymer materials on the UV aged performance of asphalt binder, a nano PA modifying agent was selected to prepare modified asphalt. Under the effect of UV radiation, the modifying effect of nano PA on the rheological properties of asphalt was studied. With the extension of UV ageing time, the microstructure variation of PA modified asphalt was characterized by using a focused ion beam scanning electron microscope (FIB-SEM). The thermophysical properties of PA modified asphalt were investigated by thermogravimetric analysis (TG). Furthermore, the functional group compositions of PA modified asphalt were investigated by dynamic FTIR. The results showed that with the extension of UV ageing time, the PA modifier could mitigate the ageing effect of UV radiation on the asphalt binder. PA modifier could achieve an increasing effect on the viscoelasticity of asphalt during the UV ageing process. PA modifier suppressed the generation of microcracks in the surface microzone of UV aged asphalt samples. PA modifier could promote the thermal stability improvement of asphalt binder when subjected to UV radiation. The generation of carbonyl and sulfoxide groups in asphalt was inhibited during the UV ageing period, which indicated that the UV induced reaction of asphalt could be postponed by the PA modifying agent.