Research on the Low-Temperature Properties of SBS Asphalt Modified with Warm-Mix Agent

Warm-mix technology for asphalt pavement is a component of sustainable social development. The low-temperature performance of a styrene-butadiene-styrene (SBS) asphalt binder modified with a warm-mix agent was evaluated. Force measurement ductility, bending beam rheology (BBR), and differential scanning calorimetry (DSC) tests were used to assess the physical indicators and rheological parameters of the asphalt binder with 2%-3.5% warm-mix agent dosages. The entropy weight method was used to quantitatively evaluate the low-temperature performance indicators of the asphalt binders. A hot-stage microscope was used to observe the microscopic phase state of warm-mix asphalt. Based on the low-temperature bending and indirect tensile cracking tests (IDEAL-CT), the anticracking performance of the warm-mix asphalt mixtures was tested; the gray correlation method was used to analyze the correlation between the low-temperature performance indicators of the asphalt binder and the anticracking performance of the mixture. The results showed that after the warm-mix agent was added to the SBS asphalt binder, the binder gradually softened, the glass transition temperature gradually decreased, and the low-temperature performance gradually improved. The warm-mix agent improved the dispersion of macromolecular substances in the asphalt binder and reduced the concentration and aggregation size of the substances. The tensile compliance (SC), yield strain energy (E), maximum tensile load (Fmax), and comprehensive compliance parameters (JC) are suitable for evaluating the low-temperature performance of asphalt binders. The low-temperature cracking resistance of the asphalt mixtures was improved by adding a warm-mix agent; Fmax, E, and JC had a good correlation with the low-temperature cracking resistance of the mixture.