Stiffening effects of LFS slags reused as filler in asphalt mixtures

Nowadays, the use of Ladle Furnace Steel (LFS) is spreading in the field of asphalt pavements. LFS are generally used as filler in Hot Mix Asphalt (HMA). The main purpose of this study is to analyse and understand the role of LFS characteristics on the possible stiffening effects of asphalt materials. Different characteristics of LFSs, such as particle size distribution, specific surface area (SSA), chemical and mineralogical properties were evaluated in addition to the performance of HMAs on different scales (mastic and HMA). One type of LFS, one standard limestone and their blends were mixed with two different asphalt binders, one pure and one 3.5% Styrene-Butadiene-Styrene (SBS) cross-linked modified. The results showed no significant correlations between the physical properties of the LFS and the performance levels of the HMAs, but it was pointed out that the LFS content in the filler blend should not exceed 30%.