PERMANENT DEFORMATION RESISTANCE OF ASPHALT CONCRETES MADE WITH ELECTRIC ARC FURNACE STEEL SLAGS

For some time now, under the pressure of a growing public awareness of the environmental problems linked with the disposal of industrial by-products, the scientific community has dedicated an increasing attention to the subject of the recovery and recycling of “marginal aggregates”, as for instance, steel slags. The paper describes the permanent deformation evaluation of both conventional and high performance asphalt concretes (Stone Mastic Asphalt, wearing course and base course asphalt concretes), for motorway pavements, made with Electric Arc Furnace (EAF) steel slags in substitution of the natural aggregates. The experimental investigation, carried out at the Road Research Laboratory of the University of Padua, involved a chemical, physical, and mechanical characterization of the EAF steel slags, followed by the mix design and the permanent deformation evaluation of the asphalt concretes, by means of Repeated Load Axial Tests (RLAT) and Wheel Tracking Tests (WTT). The requisites for acceptance in the main Italian Contract Specifications were completely satisfied (Indirect Tensile Strength up to 1.42 MPa, depending on the mixture) and the mechanical performance, in terms of permanent deformation resistance, resulted really interesting and promising. Therefore it has been experimentally verified that the EAF steel slags can be successfully recycled in the stone skeleton of the asphalt concretes investigated, moreover with extremely high content (from 89% to 93% by weight).