Evaluating the fatigue behavior of asphalt mixtures containing electric arc furnace and basic oxygen furnace slags using surface free energy estimation

This study evaluated the effects of electric arc furnace (EAF) and basic oxygen furnace (BOF) slags on the fatigue behavior of asphalt mixes. After the initial evaluation of the properties of steel slags, nine sets of laboratory asphalt mixes were prepared. For each set, different proportions of limestone coarse aggregates (≥2.36 mm) were replaced with steel slags. The main laboratory protocol involved determining the fatigue life of the samples at 20 °C. Four-point bending beam fatigue tests were performed under controlled strain mode loading at different strain levels to characterize the fatigue behavior of the asphalt mixtures. The adhesion between asphalt and aggregates were assessed using the free surface energy concept. Results revealed that the addition of slags in the mixtures considerably enhanced fatigue life but that the fatigue life of the specimens containing EAF slag was greater than that of the specimens containing BOF slag. The findings also indicated that fatigue life increased with rising slag content. The surface energy test revealed that the adhesion between asphalt and aggregate was stronger in the slags mixtures than in the limestone mixtures. Such adhesion can explain the increased fatigue life of mixtures containing slags.