Effect of asphalt mix design method on binder and gradation selection

To investigate the hypothesis that Superpave Volumetric mix design yields s uperior performing mixes overall, the Portuguese Road Directorate (JAE) com pared the performance of Superpave mixes with the performance of other mixe s. The comparisons were made with gradations that pass through, above, and below the restricted zone. Performance was evaluated using the Marshall tes t. the Hveem test, the Repetitive Simple Shear Test at Constant Height, the Four Point Bending Fatigue Test, and the French Wheel Tracking Device. The se research efforts led to consideration as to what extent the binder and g radation selections are dependent on the mix design tool. The results indic ate that some Superpave mixes yield the lowest laboratory performance in so me of the tests.