## 4 Conclusions  
The immobilization of pollutants from EADF through its introduction into ceramic geopolymers, for use in construction, has been evaluated in this work. Increasing amounts of clay have been replaced by EAFD as raw material (from 0 to 20%), and the geopolymers have been cured at two different temperatures. The impact on technological and environmental properties have been evaluated. The introduction of EAFD into the geopolymer matrix promotes the development of the flexural strength of the geopolymer regardless of curing temperature. Furthermore, the best results of water absorption were achieved with high dosage of dust and at low temperatures. From the environmental point of view, metals related to EAFD, such as Zn, Pb, or Cu, are retained in the geopolymer matrix, and the mobility of these elements decreases at highest curing temperature. However, oxyanionic elements, such as As or Se, due to the high pH that alkali produces when is introduced into water, present a very high concentration, which even exceeds the limits for non-hazardous waste disposal. Arsenic comes mainly from clay, and it barely has a concentration of amorphous silica that can geopolymerize, so the role played by clay and its possible replacement should be analyzed in future research. The use of a speciation model helps to predict the behavior and to understand the leaching mechanism. As expected by the high iron content in the EAFD, the iron complexes on the surface of the material play an important role in the immobilization of metals in this kind of matrix. Investigation, formal analysis, writing--original draft preparation: E.C. ; Methodology, investigation: J.D. ; Software, writing--original draft preparation: T.L. ; Methodology, investigation: M.d.C.D.-F.; Conceptualization, funding acquisition, and project administration: A.A.; All authors have read and agreed to the published version of the manuscript. This work was funded by the University of Cantabria \"Proyecto Puente 2017\" through a grant (PI A. Andres) under SODERCAN and ERDF Regional Operational Programme 2014-2020. Not applicable. The data presented in this study are available on reasonable request from the corresponding authors. Acknowledgements. : Acknowledge the technical support to [PERSON] and [PERSON] from the University of Barcelona, and [PERSON] and [PERSON] from the University of Cantabria. Thank the company Reciclados De Cabezon S.L. - (Cabezon de la Sal, Cantabria, Spain) for supplying the materials used in this work. The authors declare no conflict of interest. References  
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