## 4 Conclusions  
The partial conclusions defined, based on the results of the tests mentioned in the methodology, lead to the verification of the final conclusion of the investigation. Therefore, we proceed to the definition of the partial conclusions:  
* The cellulose fibers discarded from the papermaking industry have a mainly organic chemical composition, with very low or non-existing chemical element pollutants,  
Figure 11: Wheel-tracking test for the optimum combination of materials from the HC, SC, and SS families of bituminous mixtures. such as nitrogen or sulfur. Furthermore, these cellulose fibers are millimetric in size and are disaggregated, making it possible for them to be homogenized in the bituminous mixture. * Ladle furnace slag has a chemical composition consisting mainly of silicates and calcium oxide. This composition is responsible for the cementitious characteristics. At the same time, the slag has a particle density similar to that of a commercial filler, with a suitable specific surface and without the presence of plasticity. * Electric arc furnace slag has a chemical composition consisting mainly of iron oxides and wollastonite. This chemical composition conditions their higher particle density, as well as a resistance to fragmentation, to the freezing-thawing cycles and high resistance to polishing. It is worth noting the absence of colloidal particles and its excellent shape for mixtures with discontinuous grading. * Leachate from electric arc furnace slag and ladle furnace slag have concentrations of chemical elements pollutants that are lower than those required by regulations. Their use for bituminous mixtures is therefore not an environmental problem. * Discarded cellulose fibers from the papermaking industry allow higher percentages of bitumen to be absorbed in all families of bituminous mixtures without presenting problems of binder bleeding. These fibers therefore form a quality mastic with the filler and bitumen capable of withstanding the traction loads of traffic. * The void content in the mix of the families conformed with electric arc furnace slag and ladle furnace slag is similar to that of traditional mixtures. * The utilization of electric arc furnace slag, as a coarse and fine aggregate for bituminous mixtures, provides greater Marshall stability, preventing the formation of plastic deformations. In addition, the employment of this by-product creates mixtures of greater durability as reflected in the wheel-tracking test
* The use of ladle furnace slag as filler for hot mix asphalt provides excellent Marshall stability, with reduced deformations. The cementitious properties of this by-product are therefore confirmed, creating durable and resistant materials as demonstrated by the wheel-tracking test. On the basis of the partial conclusions it can be concluded that electric arc furnace slag and ladle furnace slag create more resistant bituminous mixtures, less likely to produce plastic deformation and more durable over time. In addition, the incorporation of cellulose fibers from the papermaking industry makes it possible to form a higher quality mastic without the production of bleeding. Therefore, this type of bituminous mixture can be used as a wearing course on high traffic roads. In short, this research shows the potential that exists in industrial by-products. These by-products or wastes, properly characterized and used in the ideal element of the bituminous mixture, can create sustainable materials with superior characteristics to those of conventional materials. At the same time, it is important to highlight the importance of the use of waste; on the one hand, it reduces the deposition of waste in landfills; on the other hand, it avoids the extraction of new raw materials; and finally, it provides a new life to that material. Conceptualization, F.A.C.-I., F.J.I.-G., J.M.T.-S., and J.S.-M.; methodology, F.A.C.-J., F.J.I.-G., J.M.T.-S., and J.S.-M.; software, J.M.T.-S. and J.S.-M.; validation, F.A.C.-I. and F.J.I.-G.; formal analysis, F.A.C.-I.