The environmental impact assessment of Asphalt Rubber: an interesting application for end of life tires

Today great efforts shall be done to plan effective techniques and frameworks for waste disposal and recycling, in order to keep down or even reduce, where it is possible, environmental pollution due to the storage of unproductive resources. Regarding the shortening of weaving factory for road pavement layings, a possible solution is to employ recovery materials, which are directly related to the road final use, such as tires, with the aim to enclose as much as possible the whole productive cycle and at the same time to enlarge environmental benefits. Asphalt rubber technology arises from all these concepts; moreover, it has shown to provide very good mechanical performances even at very low temperatures, which is suitable for a continental climate, with a longer duration and less maintenance required. In addition, its specific mix design has been studied both to reduce noise emissions and to optimize acoustical absorption. In this paper, we applied Life Cycle Assessment to evaluate the global environmental performances of an asphalt rubber pavement and compare it with a conventional asphalt pavement. Asphalt rubber results with a 30% improved environmental burdens on all the potential impact categories considered in respect to the traditional asphalt. This important improvement occurs despite the larger environmental impacts of AR bitumen and conglomerate production and descends from the lower amount of material requirement for the asphalt rubber pavement construction and its longer lifecycle. In a parallel evaluation, we assessed the positive environmental burdens connected to this material recycling solution, by comparing it with other common alternatives occurring in the current ELTs management scenarios in Italy, that is landfill dumping and ELTs transboundary export to Far East where the materials are further processed and recycled in rubber items, and often shipped back to Italy. A significant environmental advantage of AR scenario resulted compared to the landfill disposal alternative, while a less evident advantage was assessed compared to the export scenario. These results strongly support all those efforts aimed at the rise of material recovery solutions, such as the asphalt rubber technology among others, in order to develop a consolidated national ELTs supply chain. Having evaluated all the technical and environmental aspects of these solutions, a further support may derive from the application of Green Public Procurement initiatives.