## 2 Multi-Disciplinary Aspects of Reutilizing Waste Materials
### Lifecycle Assessment  
As a follow-up to the previous section, another crucial factor to take into account while using recycling material in pavement engineering is the economic pillar. Costs include both those associated with road users and those that have an impact on road agencies \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Country**} & \multicolumn{5}{c}{**Percentage (\%) of Recycled Asphal for Use in Reconstruction**} \\ \cline{2-6}  & **HMA and WMA** & **Cold Mixtures** & **Unbound Layers** &
\begin{tabular}{c} **Other** \\ **Miscellaneous** \\ **Works** \\ \end{tabular} & **Landfilling** \\  & & & & & \\ \hline Austria & 60 & N/A & N/A & N/A & N/A \\ Belgium & 95 & N/A & N/A & N/A & N/A \\ Czech Republic & 14 & 30 & 20 & 10 & 26 \\ Denmark & 66 & 0 & 8 & 0 & 26 \\ Finland & 100 & 0 & 0 & 0 & 0 \\ France & 70 & N/A & N/A & N/A & N/A \\ Germany & 84 & 0 & 16 & 0 & 0 \\ Hungary & 95 & 0 & 0 & 4 & 1 \\ Italy & 23 & N/A & N/A & N/A & N/A \\ Netherlands & 71 & 11 & 0 & 0 & 18 \\ Norway & 30 & 1 & 0 & 0 & 0 \\ Slovakia & 96 & 2 & 1 & 1 & 0 \\ Slovenia & 24 & 6 & 10 & 0 & 60 \\ Spain & 83 & 0 & 14 & 0 & 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Distribution of recycled asphalt in the EU, year 2017 (adapted from ([PERSON] et al., 2018)). Figure 3: Main issues with RAP performance. and operators [21]. Evaluations of the adaptability of current manufacturing methods and equipment should be carried out, together with comparisons with virgin material supply and recycled material processing [1]. A focused technological shift and a significant advancement in the relevant standards and/or recommendations can be sparked by such research. Until now, lifecycle analysis (LCA) seemed to be a complete instrument that was vital to support performance analysis of recycled mixtures and enable more thorough decision-making, while embracing recycling viewpoints [47; 48; 49; 50]. Some of the environmental benefits of using recycling materials include the natural resource preservation, the reduction of air acidification and photochemical haze caused by the usage of plastic, as well as the elimination of transportation costs associated with waste milling products to landfills [51]. [PERSON] and [PERSON] [48] have recently developed the Environmental Sustainability and Circularity Index (ESCI), which ranks the various degrees of circularity of a recyclable material. There are also cases where LCA of asphalt mixes for wearing courses might not support the use of a specific combination of materials despite the mechanical performance benefits. For example, in a study from [PERSON] et al. [47], wearing course mixtures made up of CR and RAP were compared in terms of their environmental impact with traditional pavement mixtures. For a proper planning and construction of wet rubberized mixtures, considerable environmental advantages were achieved, followed by marginal improvements after RAP addition. On the contrary, the researchers did not report environmental advantages for dry processed mixtures. From the above example, it appears that the LCA can lead to controversial results. The fact is that LCA is only occasionally performed and is used even more infrequently in the analysis of a research project. Nonetheless, it should be mentioned that the main barrier to producing trustworthy LCA inventory data is the need to take into account a number of assumptions, whether or not they are conservative. In addition, the use of international LCA tools envisages the risk of using assumptions that are only of location-specific applicability, thereby leading to results with limited prediction accuracy. Again, the issue of field-scale experiments is emphasized so that more reliable LCA can be jointly performed. Overall, LCA needs to be more methodologically retrofitted through regular investigations and holistic comparisons (Figure 4). Going a step beyond LCA, the aspect of cost is almost overlooked in the related research.