Development of bio-based stabilizers and their effects on the performance of SBS-modified asphalt

Abstract

Polymer-modified asphalt has been widely used in pavement engineering thanks to its excellent road performance. However, differences in the molecular structure, molecular weight, and density of polymer modifiers and base asphalt binders make modified asphalts prone to phase separate into the modifier and the base asphalt binder during static processes, such as transportation and storage. To ensure the storage stability of polymer-modified asphalt, stabilizers are usually added in the polymer-modified asphalt preparation process. Sulfur powder is a commonly used stabilizer with a good stabilizing effect for the preparation of modified asphalt but faces the problems of fire hazard and environmental pollution. In this study, based on the compounding process, three environmentally friendly and safe bio-based sulfur stabilizers were developed. Based on the preparation and performance evaluation of styrene-butadienestyrene block copolymer–modified asphalt under the same conditions, the effects of bio-based stabilizers on the performance of the modified asphalt were investigated. A comparative evaluation of the physical properties of modified asphalts was used to infer the high-temperature performance from the rutting factor measured by a dynamic shear rheological test. The low-temperature performance was inferred from the stiffness S and the m value measured by the bending beam rheological test. The elastic recovery performance of asphalt was characterized in terms of the average percent recovery R and the nonrecoverable creep compliance Jnr, as measured by a multiple stress creep recovery test. The microscopic morphology of the modified asphalt was observed under a fluorescence microscope. The results showed that the modified asphalts prepared with bio-based stabilizers all had low 135 °C viscosity and good high- and low-temperature performance. The best rheological parameters were found for modified asphalt prepared with Stabilizer A, followed by that prepared with Stabilizer C and then Stabilizer B. Both the original and the short-term-aged modified asphalt containing Stabilizer A showed good network structure under the fluorescence microscope. In addition, the costs of bio-based stabilizers were similar to that of traditional sulfur powder.