ORIGINAL ARTICLE Mechanical performance of asphalt rubber mixtures with warm mix asphalt additives Ana Marı ´a Rodrı ´guez-Alloza . Juan Gallego Received: 11 January 2017 / Accepted: 27 February 2017 Ó RILEM 2017 Abstract The growing concern regarding global warming has led to the recent development of warm mix asphalt (WMA) technology in the field of pave- ment materials. Production and compaction tempera- tures can be reduced by lowering the binder viscosity and in turn reduce greenhouse gas emissions (GHG) and energy consumption without significantly chang- ing the mechanical characteristics of the mixtures. There are different additives and technologies which reduce production temperatures, but not all of them have been studied, especially regarding asphalt rubber (AR) mixtures with a high content of rubber (20% over the weight of bitumen). These mixtures, with a high viscosity binder, must be produced at higher temper- atures compared to a conventional mixture. This study contrasted and assessed AR mixtures with waxes as WMA additives in order to test: water sensitivity, resistance to permanent deformation and fatigue as well as stiffness. The study demonstrated that the waxes used enhance resistance to permanent deformation without compromising fatigue resistance. Water resistance is slightly inferior and the stiffness modulus depends on production temperature. Keywords Asphalt rubber Á Warm mix asphalt Á Water sensitivity Á Rutting resistance Á Stiffness modulus Á Fatigue resistance 1 Introduction The use of waste tire material to produce crumb rubber modified (CRM) binders is highly beneficial for the preservation of natural resources. With this in mind, pavements containing rubberized binders offer multi- ple benefits: a higher resistance to rutting, fatigue and thermal cracking. Furthermore, traffic noise is reduced, maintenance costs are cheaper and pavement life is prolonged [1–7]. There is however one major drawback; production temperature is higher when compared to a conventional mixture. This is due to the greater viscosity of the binder which in turn results in a great amount of greenhouse gas emissions (GHG) production and higher energy consumption. The solution to this problem could be the Warm Mix Asphalt (WMA) technology, which is able to reduce production and compaction temperatures and also reduces odours making working conditions far better both at the paving sites and in production plants [8]. A. M. Rodrı ´guez-Alloza (&) Department of Civil Engineering: Construction, Infrastructure and Transport, Universidad Polite ´cnica de Madrid (UPM), C/Alfonso XII, 3 and 5, 28014 Madrid, Spain e-mail: anamaria.rodriguez.alloza@upm.es J. Gallego Department of Civil Engineering: Transport and Territory, Universidad Polite ´cnica de Madrid (UPM), C/Profesor Aranguren, 3, 28040 Madrid, Spain Materials and Structures (2017)50:147 DOI 10.1617/s11527-017-1020-z