Optimization of electric arc furnace aggregates replacement in dense-graded asphalt wearing courses

Electric arc furnace (EAF) aggregates, by-products of the homonymous steelmaking process, represent an ideal solution for asphalt mixtures, above all for wearing courses where skid resistance and durability are essential functional requirements. Their use, which is subordinate to the compliance of chemical specifications, finds some practical interest limits mainly related to transportation (extremely high bulk specific gravity) and placement (unsatisfactory compaction) operations. Thus, the aim of this experimental study was to determine an ideal artificial to natural aggregates replacement rate, also identifying the most suitable particle size range, for dense-graded asphalt wearing courses. The results highlighted how the best balance between compaction and mechanical performances was registered by a mix which was formulated considering a partial replacement of 54% (v/v%), distributed only in the coarsest fraction. The introduction of limestone as “excipient” in the coarse -fine and finer size ranges reduces the weight of the mixture, guaranteeing at the same time an optimum compaction degree, high levels of stiffness in the viscous-elastic region and Marshall stability and extended fatigue life.