Experimental evaluation of EAF ladle steel slag as a geo-fill material: Mineralogical, physical & mechanical properties

- EAF(L) steel slag exhibit comparable frictional properties to very angular crushed sand.
- XRD patterns of EAF(L) steel slag indicate presence of MgO as a major phase.
- The rate of free swelling of EAF(L) steel slag is relatively low due to MgO.
- By the replacement of 5-10% Class C fly ash, swelling of EAF(L) steel slag is alleviated.
- EAF(L) steel slag & Class C fly ash mixtures show potential to be used as geo-fill material.

Despite of significant efforts in the last decades towards utilization of steel slag in the construction industry, steel slag stockpiling and landfilling operations do not seem to be declining in steel-producing countries. Use of steel slag as a construction material requires understanding of its engineering properties and development of a methodology to address its swelling potential. This paper focuses on the results of a series of laboratory tests (grain-size analysis, X-ray diffraction, specific gravity, compaction, maximum and minimum dry unit weight, direct shear, and long-term swelling tests) performed on samples of electric-arc-furnace ladle (EAF(L)) steel slag to assess its potential to be used as a geo-material. Direct shear test results indicated that the EAF(L) steel slag exhibits comparable frictional properties to angular crushed sand. Based on the leachate concentration levels from TCLP analyses, the EAF(L) steel slag tested was classified as Type III Solid Waste. The long-term, one-dimensional (1D) swelling test results showed continued volumetric expansion even after more than 16 months of monitoring. Replacing 5-10% by weight of EAF (L) steel slag with Class C fly ash reduced the 1D swelling to negligible levels.