Effects of Thermal Oxidative Aging Intensity on Asphalt and Its Recycling Properties

ZHANG Henglong, ZHAO Bin, XU Guoqing, ZHU Chongzheng, BU Chaofan

Abstract

To explore the effect of thermal oxidative aging intensity on the properties of asphalt, different times of the rotating thin film oven test (RTFOT) and RTFOT + pressure aging vessel (PAV) aging tests were applied to asphalt. The conventional physical properties and dynamic shear rheological properties of asphalt samples were tested before and after aging. Additionally, the viscosity harmonic method was used to determine the amount of rejuvenating agent in order to restore the asphalt performance under different thermal oxidative aging to the matrix asphalt. The test results show that the physical properties of asphalt are significantly changed after different thermal oxidative aging intensity. The dynamic shear rheological test results exhibit that the increase ratio of asphalt complex modulus （G*） decreases obviously after the certain aging degree, and finally, the G* approaches a stable value. It is found through physical and rheological properties that, for Changlian 70# asphalt, 3 times RTFOT aging intensity is equal to the RTFOT + PAV aging intensity. In addition, through viscosity harmonic method selecting rejuvenating agent dosage, it can be found that the recycling asphalt′s G* can restore to the level of matrix asphalt，the penetration is slightly lower than the matrix asphalt，but the ductility is improved obviously. Additionally, the softening point is higher than that of matrix asphalt. At the same time，the phase angle（δ） at low temperature can be restored to the level of matrix asphalt, but it cannot be restored to the level of the matrix asphalt at high temperature.

 

Keywords: road engineering,  asphalt,  oxidative aging,  recycling,  viscosity harmonic method,  rheological properties


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References


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