MIX DESIGN OF SKID RESISTANCE BITUMINOUS MIXTURES MADE WITH STEEL SLAGS

The paper discusses the mix design of skid resistance asphalts made using Electric Arc Furnace (EAF) steel slags (from Italian steel plants), in partial substitution of the natural lithic matrix. The study has been articulated in a preliminary investigation on the chemical, physical, and mechanical properties of the EAF steel slag, and in the following Marshall mix design and Indirect Tensile Strength evaluation of five different skid resistance bituminous concretes, characterized by different steel slags content, up to 35% of the aggregate weight. The comparison between the steel slags and a conventional crushed limestone aggregate, in terms of the most significant road engineering properties, has demonstrated the several superior characteristic of the steel slags; moreover, appropriate leaching tests demonstrated that the marginal aggregate was not an hazardous material. All the mixtures with EAF slags have satisfied the requisites for acceptance in the road sector technical standards (Marshall Stability, Marshal Quotient and Indirect Tensile Strength up to 905 daN, 203 daN/mm and 1.06 MPa, respectively, depending on the mixture), thus resulting as suitable for use in the construction of high skid resistance wearing courses for roads, moreover presenting higher mechanical characteristics than those of the corresponding asphalts with full natural aggregate.