Linear Viscoelastic and Fatigue Characteristics of Styrene–Butadiene–Styrene Modified Asphalt Mixtures

Three styrene–butadiene–styrene coblock polymer modified asphalt concrete mixtures (70/100M5, 160/220M5, and 160/220M10) are characterized using complex modulus and fatigue testing. The compositions of the materials investigated are identical (aggregate size distribution, binder, and void contents) and differ solely regarding binder characteristics. The modified binders are manufactured using two base bitumens (70/100 and 160/220) modified by a styrene–butadiene–styrene coblock polymer. The fatigue tests are carried out at three different temperatures (0, 10, and 20°C) using both stress- and strain-controlled modes. A continuum damage model is used to investigate its ability to characterize fatigue of polymer modified mixtures. The results indicate that the continuum damage model is suitable for characterizing the materials at the test conditions used (mode of loading, excitation amplitude, and testing temperature) in that visually similar material functions are obtained. Using statistical analysis, it was indicated that strain amplitude does not significantly influence the model parameters of the characteristic material functions. However, even though different loading conditions lead to apparently similar material functions, the model parameter values were actually significantly affected by the testing temperature used. Predictions of fatigue path, including number of cycles to failure, based on the material functions indicate reasonable accuracy.