## 2 Literature Review
### The Use of Asphalt Mixing Plant Capacities in Europe  
The positive linear correlation (Figure 4) shows that an increase in the number of AMPs across the country (\(\overline{N}_{c}\)) results in a rising volume of the HMA and WMA mixture \begin{table}
\begin{tabular}{c c c} \hline \hline
**The Scale of the** **Amount (Mass)** & **The Amount of the Asphalt Mixture** **in Millions of Tonnes and the Rank** **of the Quantity** & **The National Abbreviation and the Actual Average** **Amount of the Mixture Produced in all the AMPs** **(Millions of Tonnes/Year)** \\ \hline \multirow{2}{*}{Very large} & 30–50 & DE (47.25); FR (37.625); TR (31.67); IT (30.57) \\  & 15–30 & ES (29.71); GB (22.575); PL (18.48) \\ \multirow{2}{*}{Large} & 5–15 & NL (9.19); AT (8.35); SE (7.93); PT (7.66); CZ (6.53); \\  & (8–16) & NO (5.80); CH (5.48); FI (53.1); BE (5.10) \\ \multirow{2}{*}{Small} & 2–5 & GR (4.91); DK (3.45); RO (3.375); HU (3.08); HR (2.99); \\  & (17–23) & IE (2.475); SK (2.025) \\ \multirow{2}{*}{Minimal} & 0.25–2 & SI (1.725); LT (1.57); EE (1.325); RS (1.30); LV (0.60); \\  & (24–30) & LU (0.597); IS (0.275) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The categorization of the countries according to the amount of asphalt mixture produced. (\(\overline{P}_{c}\)) produced in the plants. Regarding the introduced values, the average amount of the asphalt mixture (\(Q_{c,AMP}\)) annually manufactured in one AMP in each of the 30 countries, Europe and E-28 was calculated using the formula (in tonnes):  
\[Q_{c,AMP}=\frac{\overline{P}_{c}}{\overline{N}_{c}}. \tag{3}\]  
The results of the calculation (Figure 5) show that a single AMP annually mostly (more than 100,000 t) produces HMA and WMA mixtures in the following way: NL (217,773 t), LU (142,143), BE (130,769 t) and SI (100,291 t). From 80,000 to 100,000 tonnes is produced in PT (84,361 t), GB (83,364 t), SE (81,921 t) and DK (80,986 t). The amount of asphalt mixture close to the average of the European countries (from 55,000 t to 75,000 t) is manufactured in FR (75,446 t), ES (73,141 t), DE (73,120 t), AT (72,357 t), RO (68,044 t), FI (62,989 t), NO (60,291 t), CZ (59,908 t), TR (58,260 t) and PL (55,663 t). Less than the average of the European countries (from 40,000 t to 55,000 t) in a single AMP per one year is made in EE (52,475 t), HR (52,456 t), IE (48,625 t), IT (46,851 t) and SK (40,581 t). A lesser amount of the asphalt mixture (from 30,000 to 40,000 t) in a single AMP is manufactured in RS (39,394 t), LT (39,250 t), CH (38,322 t), HU (37,108 t) and IS (32,728 t). The least amount (less than 25,000 t) of the asphalt mixture in Europe is produced in the AMPs of LV (24,691 t) and GR (22,575 t). Based on the research results described above and shown in Figure 5, for a more detailed analysis, a histogram was developed to represent the frequency distribution of the average mixture production in the AMPs (Figure 6). On the vertical axis of the histogram, the widths of each interval are equal--32,533 t/year. Specifically, the histogram shows the variations in the actual annual MCs of AMPs in the European countries, which ranges from 22,575 (GR) to 217,773 t/year (NL). The difference between the maximum and minimum actual MC indicates that the use of the technical capabilities of AMPs to produce the asphalt mixture varies nearly 10-times in individual countries. The MC of new AMPs is 80-400 t/h (\"Ammann\") and 160-400 t/h (\"Benninghoven\"). The difference makes 5.0 and 2.5 times, respectively. Therefore, it is very likely that the cause for the approximately 10-times actual difference in the MCs of the AMPs is the extended downtime of the AMPs rather than significant differences in their technical mixing capacity. This statement can also be explained by the fact that an AMP usually does not produce asphalt mixtures to store them, i.e., an AMP only produces asphalt mixtures when there is a demand.