Crumb Rubber in cold recycled bituminous mixes: comparison between traditional Crumb Rubber and Cryogenic Crumb

Today recycling is one of the most innovative and interesting techniques for the rehabilitation of destressed road pavements. In recent years the increased interest in this process, has led to the development of various alternative methods for the recovery and the reuse of road bituminous materials. Cold recycling is, among the recycling techniques, certainly the most studied and developed: it allows the recovering of bituminous material from an existing pavement without the addition of heat, whilst ensuring the creation of high quality bound base layers. A wide range of materials have been tested together with Reclaimed Asphalt Pavement (RAP) and, consequently, there is a large number of variables that can be considered in the mix-design process of new eco-friendly Cold Recycled Mixes. In particular, the present research involves the use of Crumb Rubber within a mixture containing 100% Reclaimed Asphalt Pavement, cold recycled with bitumen emulsion and cement. Two different Crumb Rubbers were adopted: one from the ambient production method, and one produced with the cryogenic process. The goal of this research project was to analyze and evaluate the different physical and mechanical characteristics induced by the shared use of two different types of Crumb Rubber in the Cold Recycled Mixes.