A suitable content of powdery Ladle Furnace Slag (LFS) has to be selected to balance its hydraulic and expansive
properties when added to concrete. In this study, the performance of concrete containing two powdery LFS is
studied: H-type LFS, stabilized before use, and N-type LFS, used in its original state. Lower expansiveness was
observed in the H-type LFS, and strength development was assisted by the formation of calcium-silicate-hydrates.
Therefore, it increased the modulus of elasticity, the splitting tensile strength, and the flexural strength of
concrete. Higher hydraulicity and expansiveness were found in the N-type LFS, which improved compressivebehavior-related properties up to a content of 10% but reduced tensile-related properties. These aspects were
confirmed through scanning electron microscopy. In general, the H-type LFS improved the mechanical properties
and carbon footprint of concrete, and its use is recommended in a multi-criteria approach, although the difference between both LFS was only statistically significant at advanced ages.
