Influence of Thermo-Oxidative Aging on the Properties of SBS-Modified Asphalt Binders

The superior performance of styrene-butadiene-styrene (SBS) modified asphalt makes it widely used in asphalt pavement construction. However, SBS-modified asphalt pavement still faces an aging problem. Aging causes the performance of asphalt materials to decline and many pavement diseases. The dosage of SBS commonly used in industry is generally between 3% and 4.5%, and the performance of SBS with a high dosage needs to be explored. Therefore, in this paper, 12 modified binders were prepared with blending amounts of 3%, 5%, and 7% and the type of modifiers as linear and star. The softening point increment (SPI), viscosity aging index (VAI), rutting factor index (RFI), complex modulus aging index (CMAI), and phase angle aging index (PAAI) were used to study the antiaging performance of SBS-modified asphalt. Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) were used to study the microscopic and structural changes that occur during the aging process of modified asphalt. The result shows that when the amount of the same type of modifier is 3%-7%, the higher the amount of modifier, the better the performance of the modified asphalt. At the same content, a star modifier is not necessarily better than a linear modifier. For the same type of modifier, the larger the amount, the better the antiaging performance of the modified asphalt. Given an increase in aging time, the deterioration of the asphalt performance will deepen. Aging leads to the enhanced high-temperature performance of asphalt. The macroscopic performance of asphalt aging can be explained by the microscopic view. The aging process of modified asphalt is the cumulative process of oxidation products.