Thomas Reiche
Andreas Ehrenberg
David Algermissen
FEhS - Institut für Baustoff-Forschung e.V.

The main challenge of the steel industry for the next decade is the transformation of the steel production to fossil free process es . The CO₂ intensive route via blast furnace will be substituted by a combination of a direct reduction plant (DRP) DRP), based on natural gas and at a later stage on "green" hydrogen with an Electric Arc Furnace (EAF) or a Submerged Arc Furnace (SAF )), heated with renewable energy.
Thus, the well known latent hydraulic granulated blast furnace slag (GBS) being successfully used in cement and concrete for more than 140 years will vanish step by step GBS is used as a supplementary cementitious material not only, but in particular due to its CO₂ reduction potential in the cement/concrete production.
Whereas the DRP itself does not generate any slag, EAF and SAF will do. Both EAF and SAF slags will be very different. The reasons are e.g., the different oxidizing and reducing atmospheres and different shares of scrap input. Moreover, the new EAF slags will be also different compared to today's scrap based EAF slag. However, specific slag/metal ratios, slag volumes, chemical and mineralogical compositions
and physical p roperties of the new slags are yet unknown. Thus, also their cementitious and environme ntal properties are still unknown!
Different research projects mainly aim at creating slags with similar characteristics to GBS. The main objective is to offer furthermore a reactive material to the cement and concrete industry. The presentation will give an overview on the differentapproaches within the steel industry, the main goals, the main technical and legal challenges and some current FEhS projects.