Performance evaluation of asphalt rubber mixtures

Every year thousands of tons of old road tyres have to be disposed of, usually by means of landfill (as Construction and Demolition material or urban solid waste). In Italy, an enormous number of old road tyres are destroyed in this way instead of being re-used in different applications, despite the fact that different methodologies for the recovery, recycling or storage have been tested. The mechanical treatment of tyres is today very interesting, because it is useful in order to obtain crumb rubber aggregate which can be used in road applications such as construction and maintenance of road pavements by means of bituminous mixtures. In spite of many experiments and extensive applications in the United States and some European countries, in Italy Asphalt Rubber Hot Mixes are not very common, and the use of crumb rubber has only been tested in some small road applications. This paper discusses the results of a laboratory experiment which analysed the potentials of crumb rubber from road tyres as an additive and aggregate for bituminous mixtures in special applications for road pavements, with the aim of producing different types of asphalt that can minimize the environmental impact of traffic (low noise pavements, surfaces that reduce the transmission of traffic vibrations).