Assessing the effects of RAP, RAS, and warm-mix technologies on fatigue performance of asphalt mixtures and pavements using viscoelastic continuum damage approach

The objective of this study was to evaluate the effects of incorporating recycled materials, i.e. reclaimed asphalt pavement (RAP) and recycled asphalt shingles, and the use of warm-mix technologies on fatigue performance of asphalt mixtures and pavement structures using the viscoelastic continuum damage (VECD) approach. Material characterisation involved dynamic modulus test and direct tension cyclic fatigue test. Two parameters, namely Material Fatigue Sensitivity (MFS) and Structure Fatigue Sensitivity (SFS), were developed to represent the fatigue resistance of asphalt mixtures and their performance in pavement structures, respectively. Validity of MFS and SFS were verified by the semi-circular bend test at intermediate temperature and the field fatigue performance, respectively. Based on the MFS results, increase in the content of recycled materials compromised fatigue resistance, implementation of warm-mix technologies brought about marginal improvements, and use of soft binder yielded pronounced fatigue benefits for hot-mix asphalt mixtures with high RAP content.