Characterizing Asphalt Binder Phase Transitions via Dynamic Mechanical Analysis: Performance Implications and SARA Fraction Correlations

Asphalt is widely used as a binder in pavement engineering. The temperature-dependent phase transition behavior of asphalt binders critically influences pavement performance. This study comprehensively evaluates phase transition characteristics to establish robust performance indicators. Dynamic mechanical analysis (DMA) was employed to characterize 30 neat asphalt binders across a broad temperature range. Phase transition temperatures and moduli were derived from complex and loss modulus curves. Correlations with saturate, aromatic, resin, and asphaltene (SARA) fractions and conventional properties (penetration, viscosity, ductility) were statistically analyzed. The results revealed significant performance variations among binders of identical penetration grades. Tg effectively differentiated low-temperature behavior, overcoming empirical limitations. High-temperature indicators (T2, E20) strongly correlated with viscosity (R2 > 0.96). SARA analysis showed that saturates reduced Tg (r = −0.566) while asphaltenes increased E20 (r = 0.804). Multiple regression models confirm synergistic interactions among SARA fractions, although low-temperature indices exhibit a weaker dependence on composition. DMA-derived phase transition parameters provide physically meaningful performance indicators, superior to conventional metrics. Incorporating Tg and T2/E20 into grading systems can enhance asphalt selection for thermal susceptibility, advancing pavement durability design.