Mechanical properties of asphalt mixes with steel slags

The paper discusses the results of a laboratory study, aimed to evaluate the suitability of electric arc furnace steel slags (EAF), obtained from different Italian plants, to be recycled in the lithic skeleton of bituminous mixtures, for road flexible pavements. The research involved a preliminary evaluation of the chemical, physical and mechanical properties of the steel slags; it was followed by a characterization of both traditional and high performance bituminous mixtures (porous asphalt, stone mastic asphalt, high modulus mixes) made with steel slags. The Marshall methodology, integrated by the indirect tensile test, was used to identify the optimum bitumen content of the mixtures. The performances of the asphalt mixes were checked by means of the stiffness modulus test and the repeated load axial test. Since the requisites for acceptance in the Italian Specifications and Standards have been satisfied (Marshall Stability and Quotient and Indirect Tensile Strength up to 2,170 daN, 778 daN/mm and 3.2 MPa, respectively, depending on the mixture) and given the positive mechanical performances, it has been verified that the steel slags can be used as partial substitution (up to 51% on the weight of the aggregate) of the lithic materials in the road constructions.