A Novel Approach Based on Munsell Value for the Evaluation of Asphalt Aging Degree

In this study, a novel approach based on Munsell value was established to reveal the relationship between the aging degree and color vision of asphalt. Five different asphalt binders were treated by three types of aging protocols such as thin film oven test (TFOT), pressure aging vessel (PAV), and ultraviolet (UV) radiation, then the effects of each aging treatment on the ductility and color spectrum (collected by a spectrometer, AvaField-3) of the binders were studied. The results show that the ductility of five binders is decreased after the three aging modes (including TFOT, PAV and UV aging), nevertheless, the Munsell values show different behaviors, they become smaller after TFOT and PAV aging while becoming larger after UV aging. Scanning electron microscope (SEM) photographs show that the UV aging leads to a transformation of the binder’s surface from smooth to pleated, thus the specular reflection of the asphalt surface changes into diffuse reflection, resulting in an increase in Munsell value of asphalt after UV aging. Meanwhile, the variation of Munsell value for the asphalt after UV aging is larger than that for asphalt after thermal oxidative aging, resulting in the increase of Munsell value of asphalt which undergoes thermal oxidative aging and UV aging. Based on field data collection and analysis, a linear regression equation ( R 2 = 0.915) is established between the Munsell value and the service life of asphalt pavement, which shows that the asphalt pavement will become white with the service life-prolonging. Based on this study, the method of Munsell value can be a promising approach to evaluate the aging degree of asphalt pavement.