## 4 Conclusions  
This research deals with the recycling of two by-products, cupola slag and electric arc furnace slag, to obtain high-performance self-compacting concrete and the comparison of these with similar concrete mixes using high-quality natural aggregates (diabase) and the most common SCMs. After analyzing the rheological and physical-mechanical results obtained, the following conclusions can be drawn:  
* It is possible to obtain a viscous paste that is capable of maintaining high-density EAFS particles in suspension by incorporating fillers. A very homogeneous, symmetrical, and stable distribution of the mixture has been achieved, without segregation or concentration of coarse aggregates, despite the high density of slags. In turn, EAFS reduces concrete slump and passing ability by 10%, while the flow rates are reduced more noticeably compared to reference mixes, due to their high viscosity.
* The incorporation of EAFS coarse and fine aggregates increases the density by 15% with respect to the reference mixes, obtaining high density concretes (>2800 kg/m\({}^{3}\)). The open porosity of all mixes is very similar (5-6%) except for the mix that uses fly ash, due to a gasifying reaction with the superplasticizer additive. Likewise, the high content of rapid cement and the low w/c ratio have resulted in all mixes thixotropy gelation of the paste, more pronounced effect on concrete with EAFS.
* For the different cement replacements by cupola slag in mortars, it is worth mentioning the low speed of the reactions of the cupola slag, showing compressive and flexural strengths similar to mortars without replacement for ages of 90 days.
* The incorporation of cupola slag leads to an increase in compressive strength after 28 days of about 10% with respect to other SCM's. The use of EAFS aggregate provides a 5% improvement in the compressive strength with respect to diabase using the same SCM. The mixes that incorporate cupola slag SCM have evolved twice as much as the rest of the mixes from 28 to 360 days. The elastic modulus of mixes with EAFS is 24% higher than the mixes with diabase and the elastic  
Figure 9: Tensile splitting strength at 90 days for all mixes.  
modulus of mixes that use slag cupola powder is 10% higher than the mixes with traditional fillers. In the case of the elastic modulus, practically 90% of the value at 360 days is obtained after 7 days. No significant differences were found in the tensile splitting strength at 90 days for all the mixes.  
Conceptualization, J.A.P. and C.T.; methodology, C.T. and I.S.; validation, J.A.P. and J.S.; formal analysis, I.S. and P.T.; investigation, I.S.; data curation, I.S.; writing--original draft preparation, I.S. and P.T.; writing--review and editing, C.T. and P.T.; visualization, I.S.; supervision, J.A.P. and C.T.; project administration, C.T. and J.A.P. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The authors of this research would like to thank GLOBAL STEEL WIRE for the EAF slag supply and Saint Gobain Pam Espana for the Cupola Furnace Slag as well as ROCACERO for providing the cement, natural aggregates and superplasticizer additive.  
The authors declare no conflict of interest.