Effect of Mixing Time and Temperature on Cracking Resistance of Bituminous Mixtures Containing Reclaimed Asphalt Pavement Material

The use of reclaimed asphalt pavement (RAP) in bituminous mixtures is considerably increasing due to the environmental and economic benefits of recycled materials. However, stiffer mixes, usually resulting from RAP addition, have raised concern about long-term properties of the pavement; a mechanical characterization of these mixes is thus needed. In this study, the effect of mixing condition on bituminous mixtures containing RAP was evaluated. Volumetric and mechanical properties were analyzed. An experimental program, with the aim of measuring stiffness modulus, water sensitivity, and cracking resistance, was conducted. Cracking resistance was evaluated according to the Fenix test because it has proved to be a convenient and effective method for characterizing cracking behavior of bituminous mixtures at different temperatures. Mixtures containing 20 or 40% of RAP material were tested; virgin aggregates and RAP mixing temperatures as well as mixing time were varied and comparisons with a reference mix were conducted to characterize fracture energy and mechanical performance.