Evaluation of Fatigue Behavior of Asphalt Mixes Containing Electric Arc (EAF) and Basic Oxygen Furnace (BOF) Steel Slags Subjected to Long Term Aging

Utilization of byproducts of steel production factories in civil engineering infrastructures has progressively been increased in recent years. Increased spending on highway construction from one hand and environmental issues from the other hand also promotes application of these materials. Steel slags have similar physical properties to conventional aggregates and can be used into both surfacing and base asphalt layers. In this work fatigue behavior of asphalt mixes containing EAF and BOF steel slags were evaluated at both laboratory aged and non-aged conditions. Nine sets of laboratory mixtures were prepared. Each set was treated replacing various portions of limestone coarse aggregates (≥ 2.36 mm) with EAF and BOF steel slags. Four point bending beam fatigue testing was performed in controlled stress mode at various stress levels to characterize fatigue behavior of these asphalt mixes. Two approaches were applied to analyze the fatigue tests data, one was based on stiffness and the second one was a dissipated energy concepts. Moreover, in order to evaluate long term performance of mixes containing EAF and BOF slags, the specimens were subjected to laboratory aging condition according to AASHTO PP2 standard testing method. The results showed that the inclusion of EAF and BOF slags in mixes improved fatigue life of samples considerably. For aged specimens, the fatigue life did not change appreciably. This was as a result of greater stiffness of mixes containing low percentages of EAF slag. This finding approved the hypothesis which suggest that the greater the adhesion, the greater would be mitigation of aging in asphalt mixes.