## 3 Life Cycle Inventory
### Material Production
#### 3.1.1 Asphalt  
An asphalt pavement is a blend of mineral aggregates and bitumen. The percentages vary according to the use and production techniques. The bitumen content is approximately 4-6%, and the rest is made up of gravel, sand and/or mineral filler and possibly reclaimed asphalt pavement (RAP). The environmental impacts of asphalt production depend to a great extent on the bitumen content, on the RAP content [24] and on the technology used to produce it (hot mix asphalt, warm mix asphalt or cold mix asphalt) [51]. The environmental performance of asphalt pavements is very sensitive to transportation distances, hence the comparisons that can be made are very site specific [48]. The transportation of the asphalt to the construction site varies according to the contingency, but it is suggested to keep this value as low as possible. The distance between the construction and production sites should not be longer than 80-100 km, especially for hot mix asphalt (HMA), because bitumen has to be kept at a high temperature to be workable during paving operations. [52]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Materials** & **Use** & **Quantity Per km** \\ \hline Asphalt & Wear and binder layers & 992,394 kg \\ Bituminous emulsion & Bond between layers & 2190 kg \\ Concrete & Coil housings & 113,760 kg \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The materials per km of e-road. The choice of the mixture for an asphalt road surface is closely related to the purpose of the road, to site specific aspects, etc. The production of a traditional asphalt mix requires that the aggregates are completely dry before they can be bound with bitumen (which is hydrophobic). This requires heating the aggregates up to 160 \({}^{\circ}\)C. Warm mix asphalt (WMA) is the name that is given to a variety of technologies that allow asphalt mixtures to be produced at lower temperatures. According to the European Asphalt Pavement Association (EAPA), WMA is generally produced over a temperature range of 100 \({}^{\circ}\)C to 140 \({}^{\circ}\)C, while the half-warm mix asphalt (HWMA) is fabricated between 70 \({}^{\circ}\)C and 100 \({}^{\circ}\)C [53]. The standard hot mix asphalt (HMA) is instead produced at approximately 160 \({}^{\circ}\)C. The cold mix asphalt has recently gained attention, since it is prepared at ambient temperatures. In order to model asphalt production, a suitable mixture for the wear and binder layers was used. The weight percentages of the different components of the mixture are reported in Table 4[24]. The extraction of these raw materials was modelled using the EcoInvent database, version 3.3. The HMA production has been considered. The emissions and energy consumption for HMA production were derived from the study of [PERSON] et al. [24]. The use of recycled asphalt, a possible solution that has been suggested to obtain a reduction in environmental pressure, requires a deeper investigation of this type of application. In some cases, a thicker layer is required to ensure the same performances as virgin asphalt. The thickness is an important variable in the case of an e-road, since it directly affects the charging efficiency. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Materials** & **Sand 0/3** & **Gravel 3/6** & **Gravel 6/12** & **Filler** & **Bitumen** \\ \hline Percentage & 16.90\% & 36.60\% & 35.70\% & 5.70\% & 5.10\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Asphal composition [24].