## 3 Results and Discussions
### Characterization of Raw Materials
Figure 3: Results of X-ray diffraction of ladle furnace slag. In addition, a series of physical properties were analyzed which are essential for evaluating the suitability of a material which performs the function of a filler in bituminous mixtures. These physical properties of the ladle furnace slag are detailed in Table 6.  
The particle density of the ladle furnace slag does not differ greatly from that of a commercial filler, 2650 kg/m\({}^{3}\), so no volumetric corrections are necessary. In turn, the bulk density of the slag studied reflects an acceptable result, not being qualified as a powdery material. Finally, the null plasticity index of the ladle furnace slag shows the inexistence of particles that could cause subsequent expansion problems, such as clayey particles. Based on the above, it can be established that the chemical composition and physical properties of the ladle furnace slag are suitable for use as filler in bituminous mixtures. On the other hand, the electric arc furnace slags were analyzed chemically. For this purpose, the elemental analysis test was first carried out. The results of this test are shown in Table 7.  
The elemental analysis test reflected the chemical composition of an inorganic material, existing low percentages of carbon and hydrogen. At the same time, the inexistence of nitrogen and sulfur was reflected, demonstrating the non-production of polluting lixiviates of these chemical elements. As it is an inorganic material, the X-ray fluorescence test was carried out in order to quantitatively determine the presence of the rest of the chemical elements not analyzed in the elemental analysis. The results of this test are shown in Table 8.  
The chemical composition of the electric arc furnace slag is directly derived from its production process. Therefore, there are high percentages of iron, as it is the main element of steel, as well as calcium, a chemical element present in the additive to the molten liquid for the formation of the slag. In turn, silicon and aluminum are common elements present in the scrap that is used to manufacture steel. Magnesium, manganese, and chromium are also common in the composition of steels. The other elements are found in such a reduced proportion that they do not produce modifications in the properties of the final material. However, the leachate test was subsequently carried out to verify that the concentration of the polluting chemical elements is below the limits set by the regulations. Once the elemental composition had been determined, the main chemical compounds were identified through the X-ray diffraction test. The diffractogram derived from the X-ray diffraction test of the electric arc furnace slag is shown in Figure 5. \begin{table}
\begin{tabular}{c c c} \hline
**Test** & **Standard** & **Value/Unit** \\ \hline Particle density & UNE-EN 1097-7 & 2.71 \(\pm\) 0.07 t/m\({}^{3}\) \\ Bulk density & UNE-EN 1097-3 & 0.75 \(\pm\) 0.01 t/m\({}^{3}\) \\ Plasticity index & UNE 103103/UNE 103104 & No plasticity \\ \hline \end{tabular}
\end{table} 
Table 6: Density and plasticity tests for the fine portion of ladle furnace slag. \begin{table}
\begin{tabular}{c c c c c} \hline
**Sample** & **Nitrogen, \%** & **Carbon, \%** & **Hydrogen, \%** & **Sulfur, \%** \\ \hline EAFS & 0.005 \(\pm\) 0.001 & 0.164 \(\pm\) 0.003 & 0.044 \(\pm\) 0.001 & 0.000 \(\pm\) 0.001 \\ \hline \end{tabular}
\end{table} 
Table 7: Elemental analysis of the electric arc furnace slag. The diffractogram of the electric arc furnace slag reflected the high content of amorphous or non-diffracting material. Iron oxide and mixed iron and manganese oxides were identified as the main phases. Wollastonite was also identified in a smaller proportion. Therefore, and unlike the ladle furnace slag, the results reflect the chemical composition of a much more stable material in which the chemical compounds present do not lead to variations in shape. In other words, the expansiveness of these electric arc furnace slags is non-existent.