Estimating asphalt binder fatigue at multiple temperatures using a simplified pseudo-strain energy analysis approach in the LAS test

Abstract

The linear amplitude sweep (LAS) test is considered an effective tool for evaluating the fatigue behavior of asphalt binders. However, because of the inherent viscoelastic nature of binders their fatigue life varies with temperatures. This leads to a challenge of selecting the LAS testing temperature for screening binders. Recently, an idea of incorporating the time–temperature superposition into the simplified viscoelastic continuum damage (S-VECD) model based on the pseudo-strain energy (PSE) concept is suggested as an opportunity for predicting the fatigue behavior at other temperatures of interest. This study investigates the temperature dependency of the material integrity-damage intensity (C-Damage Intensity) curves derived from the PSE analysis. The results show that the time–temperature superposition is not always applicable for the C-Damage Intensity curves in the PSE analysis. It is however found that those curves at various temperatures have their inherent correlation, allowing the prediction of fatigue behavior at other temperatures. A simplified approach is introduced in this study in which the shift factors measured from frequency sweep portion of LAS tests are used to predict the C-Damage Intensity curves and calculate the fatigue life at other temperatures. The results from this approach is found to correlate very well with the measured fatigue life of asphalt binders.