Analysis of Fatigue Test for Bituminous Mixtures

Abstract

In this study, cyclic tension-compression tests on cylindrical specimens are performed in order to investigate fatigue characteristics of bituminous mixtures. Sinusoidal loading is applied at 10 Hz in controlled axial strain mode at 10°C. Axial strain and axial load are measured as well as radial strain, thanks to a specially designed device. The evolution of Poisson’s ratio and volumetric strain is observed during fatigue tests. Fatigue test results are analyzed considering six different fatigue life criteria (using either classical complex modulus drop, nonhomogeneity of the strain field, or dissipated energy evolution, among others). During the first phase of fatigue tests, some skewing phenomena (e.g., thixotropy and heating) are predominant and create reversible effects that must not be interpreted as fatigue. A method to take into account these phenomena is also applied to obtain a corrected damage value at failure. This parameter is shown to be a constant intrinsic value. Based on this result, a new approach is also proposed to predict failure. This method enables stopping tests at 300,000 cycles. The approach has the interest to limit the testing time duration to less than 8.5 h (with 10 Hz frequency).