Effect of Analysis Procedures in Linear Amplitude Sweep Test on the Fatigue Resistance of Nanoclay-Modified Asphalt Binders

Abstract

The present study aims to quantify the fatigue characteristics of nanoclay-modified binders, considering different analysis procedures in the linear amplitude sweep (LAS) test. Four unmodified and modified asphalt binders were subjected to the LAS test at 10°C, 20°C, and 30°C. The fatigue life obtained using five different analytical methods were assessed and compared. The effect of controlled strain rate (CSR) used in the LAS test was not found to be significant in changing the fatigue ranking of asphalt binders. Different analytical methods produce different fatigue curves with no change in the relative ranking of the binders at each temperature. The model parameters (a and b) obtained by fitting the relationship between average released pseudostrain energy (GR) and the number of cycles to failure (Nf) can significantly impact fatigue life, resulting in a discrepancy in the results. This discrepancy, across different temperatures and binder types, can be removed by smoothening of the model with b=−2. The unified GR–R-based analysis, as is proposed in this study, results in a lower value of fatigue life at lower strain susceptibility in the standard fatigue model. Statistical analysis reveals that there is no distinct influence of nanoclay on the fatigue life of asphalt binders. Inclusion of nanoclay results in either similar or marginally higher fatigue life at all the temperatures. The analysis and results support the use of a GR–R-based approach for quantifying the fatigue life of asphalt binders.