# End-of-Life Tyres: Comparative Life Cycle Assessment of Treatment Scenarios
## 1 Introduction and State of the Art
Literature on ELTs management is quite abundant and environmental assessments have been performed for different tyre treatments and recovery methods. However, results are often difficult to compare or are scarcely reproducible because of lack of inventory data. [PERSON] et al. [12] have provided LCA impact assessment for nine recovery treatments and concluded that the most beneficial scenarios are the production of synthetic ELT-based turf, the manufacturing of moulded objects from ELT and energy recovery in cement works. However, authors did not provide the input/output data employed for the analyses (the Life Cycle Inventory, LCI), and, as a consequence, the study is not easily replicable and updatable. Artificial turf and energy recovery in cement plant has been identified as the most environmental friendly solutions also by [PERSON] et al. [13], who provided a complete analysis considering nine scrap tyre applications. Different scenarios were considered by [PERSON] et al. [14], who assessed the treatments of ambient grinding, dynamic devulcanization, pyrolysis and illegal tyre oil extraction, concluding that the most environmental friendly scenario is the pyrolysis one. Even though pyrolysis of ELT is rarely performed [15], characteristics of this process have been recently analysed also by [PERSON] et al. [16] and its environmental performance has been compared with other scenarios by [PERSON] [17]. According to the Waste Framework Directive (2008), reuse and recycle of waste should be prioritized compared to energy recovery. In line with this directive, the study of [PERSON] et al. [18] demonstrated that higher environmental impact reductions can be obtained for the material recycling route relative to energy recovery in a cement kiln. Among the most investigated recycling routes there is the use of crub rubber (CR) for asphalt mixtures. [PERSON] et al. [19] compared environmental impacts of asphalt with and without crumb rubber, resulting that this latter presents environmental benefits. [PERSON] [20] compared with a detailed LCA study the reuse for asphalts with other three different scenarios (production of floor, production of wire and landfill). As well, [PERSON] et al. and [PERSON] et al. [21; 22] compared the use of CR with the use of reclaimed asphalt pavements (RAP). A literature review on environmental impacts of rubberizedasphal has been provided by [PERSON] et al. [23]. Emissions caused by CR used in asphalts has been the focus of the studies of [PERSON] et al. and [PERSON] et al. [24; 25]. Few studies, such as the LCA analysis of [PERSON] et al. [26], are available on the reuse of CR to produce new tyres. A very specific application of ELT was studied by [PERSON] and [PERSON] [27], who developed a process to employ this waste for the production of catalyst for biodiesel. In this literature context, this paper aims to investigate the environmental impacts of two different scenarios of ELT treatments. Specifically, it is analysed the recycling of CR deriving from the tyre shredding for the composition of bituminous mixtures for the wearing course of roads and this scenario is compared with the energy recovery route in a dedicated incinerator. To this aim the standardised methodology of Life Cycle Assessment (LCA) (ISO 14040-44) is employed. Results of this analysis will provide specific LCA-based information able to help decision-making in understanding which one of the analysed ELTs treatment offers the highest environmental benefit. This work is therefore expected to support the scientific community and the tyres waste sector in the identification of the most suitable final treatment, where actions should be preferentially addressed to improve the environmental profile.