Investigation of aging performance of SBS modified asphalt with various aging methods

Two kinds of base asphalts (penetration 70 and 90) were used for preparing styrene-butadiene-styrene block copolymers (SBS) modified asphalts. The obtained two kinds of SBS modified asphalts were designated as SBS-70 and SBS-90. Then three types of aging methods such as thin film oven test (TFOT), pressure aging vessel (PAV), and ultraviolet (UV) radiation were applied. The effects of each aging method on the physical characteristics, rheological property and chemical composition of the binders were studied. The Fourier Transform Infrared Spectroscopy (FTIR) was used to measure the chemical structures of modified asphalts. The morphological characteristic of SBS modified asphalts was determined using fluorescence microscope (FM). The results show that SBS-90 displays the higher retained penetration and ductility as well as the lower viscosity aging index in comparison with SBS-70, which is in accordance with the aging results of base asphalt. According to the rheological test, SBS-90 shows a larger complex modulus aging index and a smaller phase angle aging index than that of SBS-70. All the above results indicate that the aging degree of SBS-90 is higher than SBS-70. This conclusion also can be proved by the results of FTIR and FM analysis. In addition, compared with PAV aging, UV aging shows more obvious influence on the degradation of SBS copolymer.