Fatigue performance of recycled hot mix asphalt: A laboratory study

The paper introduces and analyses the results of an experimental trial on the fatigue resistance of recycled hot mix asphalts for road pavements. Based on the gyratory compaction and the indirect tensile strength test, the mix design procedure has optimized nine different mixes, considering both conventional limestone and Reclaimed Asphalt Pavement (RAP), the latter used at different quantities, up to 40% by weight of the aggregate. A standard bitumen and two polymer modified binders were used for the production of the mixes. The fatigue study was carried out with four point bending tests, each one performed at 20°C and 10Hz. The empirical stiffness reduction method, along with the energy ratio approach, based on the dissipated energy concept, were adopted to elaborate the experimental data. Unaged as well as aged specimens were checked, to analyse the ageing effects on the fatigue performance. In comparison with the control mixes, produced only with limestone, improved fatigue performance was noticed for the mixtures prepared with RAP, especially when made with polymer modified binders, under both aged and unaged conditions. Both the approaches adopted for the experimental data analysis have outlined the same ranking of the mixes.