Effect of ultraviolet (UV) aging on rheology properties and microstructure of polyurethane (PU) modified asphalt

Abstract

In order to investigate the effect of polyurethane (PU) modifier on the anti-UV aging ability of asphalt, in this study, the base asphalt and PU modified asphalts were subjected to short-term UV and long-term UV aging. After that, three tests, including physical property test (penetration and ductility), dynamic shear rheology test (DSR) and atomic force microscopy (AFM) test were used to evaluate the effect of UV aging on the performance of PU modified asphalt. The test results show that the change rate of softening point and ductility of PU modified asphalt is lower than that of base asphalt after aging. The PU modifier reduces the effect of UV aging on the complex modulus G* and phase angle δ of the asphalt. In addition, AFM was used to observe the morphology of asphalt before and after UV aging. The results showed that the addition of PU modifier can hinder the movement of small molecules in the asphalt, leading to the microstructure of the asphalt more stable. Through statistical analysis of the height and modulus of asphalt surface morphology, it is found that the effect of UV aging on the surface height and modulus of PU modified asphalt is less than that of the base asphalt. This indicates that the PU modifier could significant improve the UV aging properties of asphalt binders.