# Comparative \"from Cradle to Gate\" Life Cycle Assessments of Hot Mix Asphalt (HMA) Materials
## 2 Data and Methods
### Inventory Analysis Phase: Primary Data  
As explained previously, in the LCI phase, the authors collected primary data directly from the two mix plants, named Company 1 and Company 2. The year 2014 was selected as the reference for the analysis. Information for both companies for this year is presented next. Company 1 includes aggregates that are both natural (purchased from the quarries) and recycled (from recycling plants), and 20% of the total aggregates used in the binder mixes belong to the second group. The bitumen used in the production of the HMA comes from two refineries located in Falconara and Livorno (Italy), and the limestone material is extracted from a quarry in Riofreddo (Figure 2, obtained from Google Earth, and Table 2). In terms of transportation, bitumen and fuels are transported from the refineries to the plant by tankers with a capacity of 30 m\({}^{3}\), and aggregates are transported from the quarry to the plant by trucks with a capacity of 20 m\({}^{3}\). Regarding the energy sources used in the plant, the burner and the thermal oil boiler work with methane gas, and the annual consumption of natural gas is 730,835 m\({}^{3}\), while the annual electricity consumption is 392,020 kW. Finally, the annual production of asphalt concrete in this plant is 49,758 m\({}^{3}\) (the average hourly production is 80 m\({}^{3}\)). Table 2 lists the distances of the raw products to the mix plant of Company 1. Similar to Company 1, aggregates in Company 2 are both natural (purchased from the quarries) and recycled (from recycling plants), and 20% of the total aggregates in the binder mixes are recycled. In this case, the bitumen is obtained from two refineries located in Falconara and Livorno (Italy) and limestone is extracted from a quarry in the city of Anagni (Figure 3, obtained from Google Earth). Regarding the transportation of raw materials, bitumen and fuels are transported from the refineries to the plant by tankers with a capacity of 20 m\({}^{3}\), while aggregates are transported from the quarries to the plant by trucks with a capacity of 20 m\({}^{3}\). Energy sources in this plant include low-sulfur crude oil, which is used to feed the oven in the plant mix, and gasoil, which feeds the diathermic oil boiler. The annual consumption of gasoil is 107,640 kg and the annual consumption of low-sulfur crude oil is 533,073 kg. In terms of production, this plant manufactures 51,257 m\({}^{3}\) of asphalt concrete per year (the average hourly production is 101 m\({}^{3}\)). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Primary Data—Company 1** & **Place** & **Distance (km)** \\ \hline Aggregates & Riofreddo & 73 \\ \hline \multirow{2}{*}{Bitumen} & Falconara & 322 \\ \cline{2-3}  & Livorno & 325 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Geographical data of Company 1. Figure 2: Company 1 geographical data. Table 3 lists the distances of the raw products to the mix plant of Company 2. Tables 4 and 5 show the smokestacks emissions in both mix plants. The data presented in these tables were obtained following the UNI EN ISO 16911-1:2013 standard [49], which regulates the methods for sampling and analyzing the control of emissions. It is noteworthy that a third party certified these data. The oxygen content by volume in the waste gas corresponds to 17% for Company 1 and to 16% for Company 2.