Recycling of tyre rubber in porous asphalt using the dry process: a laboratory characterisation

Recycling of tyire rubber in the road pavement, may be one of the best way to reduce waste tires in large quantities and, at the same time, improve some engineering properties of asphalt mixtures. The paper discusses the results of an experimental study, in order to analyse the potentialities of crumb rubber from road tyres in bituminous mixtures, using the dry process. Two types of porous asphalt mixtures, over the control mixtures without rubber, were formulated by means of the traditional Marshall methodology, and mechanically evaluated by means of the Indirect Tensile Stiffness Modulus test (ITSM), the Creep test (with confinement), and the Indirect Tensile Fatigue Test (ITFT). Results of this study indicate that the tyre rubber could have a different influence on the performance characteristics, depending on the grading and volumetric properties of the mix being studied: an interesting increase of the fatigue life, a better stiffness behaviour at lower temperatures and a bigger permanent deformation resistance resistance at high temperatures.