Incorporation of steel slag and reclaimed asphalt into pavement surface layers

There is an increasing concern about the recycling and reuse of wastes in different areas. This research aims to analyze the technical viability of the use of Reclaimed Asphalt Pavement (RAP) and Steel Slags (SS) for the composition of asphalt mixtures for surface layers. Therefore, three asphalt mixtures AC 10 were designed: without recycled materials (R), with 30% of RAP (F) and with 30% of SS (A). They were mechanically and superficially assessed. Their water sensitivity and the permanent deformation were similar. The mixture A presented higher stiffness modulus and lower fatigue resistance when compared to the other ones. The best sound absorption and mechanical impedance found were for A and the worst ones were for F. Mixture A had smoother macrotexture if compared to the other mixtures. The asphalt mixtures had similar friction. It can be concluded that these wastes can be incorporated in asphalt mixtures for surface layers. Other wastes from different sources have already been incorporated in the Paving Industry. It is worth mentioning the use of slags, the by-product of the Steel Industry. This residue has already been incorporated into asphalt mixtures, from base courses to surface layers. Generally, there are two types of slags produced by the industry: i) blast furnace: obtained directly from blast furnace; (ii) steel: resulting from the production of steel, obtained in electric furnaces and in oxygen converters. Some of its limitations are associated with its high density, causing higher transport costs, its high water absorption, which can increase the binder content, and its high expansion, requiring a curing period before the incorporation (Fakhri and Ahmadi, 2017). Due to its metallic material content, mainly iron oxide (Fe2O3), the SS present high electrical and thermal conductivity. Thus, asphalt pavements composed of this material, when irradiated by microwaves, can melt easier snow on its surface during the winter when compared to conventional asphalt pavements. Therefore, it can be portrayed as a new function of asphalt mixture, since this property is not considered as an essential one (Gao et al., 2017). The literature points out that most of the researches are about the mechanical characterization of recycled asphalt mixtures, but not the functional (superficial) characterization (mainly taking into account the use of SS). Thus, this research aims to analyze the technical viability of the use of RAP and SS for the composition of asphalt mixtures for the surface layer of road pavements.