## 3 Results and Discussion
### Mechanical Performance  
In terms of stability, two indicators were assigned: Marshall stability and Marshall deformation. Both properties were well represented by a normal distribution (see Figure 10); thus, the boundaries of the labels were defined according to the probabilistic criteria mentioned in Section 2.2. Figure 9: Flowchart of the global labeling scheme. The Spanish technical standard establishes a minimum value for Marshall stability. This may lead to the assumption that a higher stability value results in a greater performance, but this is not true for wearing courses for thin layers. A bituminous mixture with a high stability value may result excessively stiff and lead to a brittle fracture. For this reason, a maximum value was also defined, and the limits were established symmetrically; the 50 th percentile was designed as the optimal stability. Indeed, the standard establishes different minimum values based on the type of mixture: dense and semi-dense mixtures, also known as asphalt-concrete (AC) mixtures, and gap-graded mixtures [33]. Hence, different labels were developed depending on the type of mixture (see Figure 11). A global label was also defined for cases where the nature of the mixture was unknown, and the chosen minimum and maximum values corresponded to the less restrictive mixture type to avoid penalizing mixtures that may comply with the standard (see Figure 12). In any case, it is recommended to verify the type of mixture. Figure 11: Marshall stability labels based on the type of mixture. Figure 12: Marshall stability global label. Figure 10: Histogram and normal distribution curve of stability indicators. In the case of Marshall deformation, it only applied to AC mixtures, and the technical standard defines a value range (see Figure 13); thus, the limits were also defined symmetrically [33]. For open graded friction courses, dosage criteria were based on the resistance to disaggregation or the loss of particles of the mixtures, and the performance test was the dry Cantabro losses (%) test [20; 33]. The obtained values for this indicator were well fitted by a log-normal distribution, and the technical standard established a maximum of particle loss depending on the mixture type (see Figures 14 and 15). Concerning water sensibility, the current test to evaluate binder-aggregate tackiness is the indirect tensile strength ratio (ITSR) test. The Spanish technical standard defines different minimum values for conserved indirect tensile strength after water immersion depending on the mixture type [20]. Indeed, it distinguishes two groups: (1) AC mixtures and permeable friction courses, and (2) gap-graded and  
Figure 14: Disaggregation resistance labels based on the type of mixture. Figure 13: Marshall deformation global label. Figure 15: Disaggregation resistance global label. asphalt concrete friction courses. The first group followed a normal distribution pattern, while the second one could not be represented either by a normal or a log-normal distribution; thus, the limits of the labels were directly applied to the sorted values (see Figures 16 and 17). Finally, all results related to the cracking resistance of the mixture were obtained during the laboratory stage. In this case, two opposite indicators are used to explain this property. On one hand, the tensile strength (TS) represents the cohesion provided by the asphalt mastic and, on the other hand, the displacement at 50% post-peak load (d\({}_{0.5\text{PostFmax}}\)) is directly related to the ductility of the mixture. Both indicators must be satisfied at the same time. For this reason, the boundaries were not established through the cumulative distribution curve, but through a TS-d\({}_{0.5\text{PostFmax}}\) graphic; the admissible limits were mapped, resulting in different performance areas (see Figure 18) [34]. In the case that both indicators are not satisfied at the same time, the resulting label class will be the most restrictive one. Figure 16: ITSR labels based on the type of mixture. Figure 17: ITSR global label.