At present, steel production is mainly done in basic oxygen furnaces (BOF) and electric arc furnaces (EAF) (Pauliuk, S. et al, 2013, Morfeldt, J. et al, 2015). According to the statistics, it is expected that the use of electric arc furnaces to supply the demand for steel will prevail. In 2017, in Europe, 41% of steel was produced in electric arc furnaces, while in Spain, according to the Union of Steel Companies (UNESID, 2016), the percentage was almost 66% in 2016. In 2016 the European Union generated approximately 18.4 Mt of slag (black and white), of which 1.5 Mt was produced in Spain. In other words, the amount of white slag produced was about 286 thousand tons, approximately between 20 and 30 kg of slag per ton of steel (UNESID, 2016, Euroslag, 2016). Refining slag (white slag) is the second most abundant waste in steel production, and, to date, its final destination is still the landfill. This study has used ladle slag from refined steelworks, as a replacement for cement in different proportions (0, 25, 50 and 75%), for the manufacture of mortars. A broad characterization of the ladle slag has been carried out, as well as determining the mechanical, durable, and environmental properties of the manufactured mortars. The results show that using the ladle slag as a replacement for cement produces a decrease in compressive strength, but the expansion behavior remains below the stability limit. It also has been seen that the slag incorporated into mortars, evaluated by leaching test at 28 days, shows inert material behavior.