Artículo de publicación Web of ScienceVolumetric expansion tests are performed on both ladle furnace slag and mixtures with natural soils, with a view to their use in civil engineering projects such as embankment construction and related earth works. The study provides an analysis of the effects of magnesium oxide and proposes an analytical model to predict LFS expansion within shorter time frames than the potential expansion tests specified in the ASTM D 4792 standard. It was found that major chemical reactions between the mixture of clayey soils and the slag occurred in the first 40  h of the potential expansion test. An acceptable relationship was also established between the values of the potential expansion test and the CBR swelling test described in ASTM D 1883.