Fatigue Characteristics of Superpave and Hveem Mixtures

Abstract

A study was conducted to evaluate the fatigue characteristics of hot mix asphalt (HMA) mixtures designed using the Superpave volumetric method and Nevada’s Hveem method. Fatigue characteristics were evaluated using the flexural beam fatigue test under the strain-controlled mode of loading. The influence of long-term oven aging on the fatigue performance was also evaluated. Analysis of variance statistic and principal component analysis were used for comparing and ranking mixtures fatigue performance. Results indicate that Superpave mixtures performed better in fatigue than Nevada’s Hveem mixtures on two projects while the opposite was observed on the other project. Additionally a reduction in fatigue life was observed for the unmodified asphalt mixtures in general as a result of aging, whereas the polymer modified asphalt mixtures didn’t show any reduction in fatigue resistance due to aging. An increase in the initial flexural stiffness didn’t necessarily reduce the beam fatigue life in the strain-controlled mode of loading. Two generalized performance models are presented in this paper. The first model relates the number of load repetitions to failure to the tensile strain and the flexural stiffness of the mixture, while the second model includes a volumetric term that is a function of the asphalt binder content and air voids. The multiple linear regression analysis indicates that the model accuracy increases significantly when the volumetric term is included.