Experimental investigation of performance properties of asphalt mixture designed with the re-recycled RAP and EAFSS

In this paper, the combined use of re-recycled reclaimed asphalt pavement (RAP) and Electric Arc-Furnace Steel Slag (EAFSS) is experimentally investigated and evaluated. First, a virgin asphalt mixture for surface layers is prepared and next aged in the laboratory to reproduce artificial RAP. Then, this material is used to prepare a set of first generation recycled mixtures which further undergoes the same procedure to finally produce RAP and mixtures presenting a second generation of recycling (re-recycling). Meanwhile, the combination of EAFSS and RAP of different generations is also incorporated in the mix design. Fatigue, low temperature creep, and fracture tests are conducted to evaluate the mixtures’ mechanical properties. Both recycled and re-recycled mixtures prepared with or without slags shows better fatigue behavior than virgin material. Higher stiffness and poorer relaxation response are exhibited by re-recycled RAP mixtures compared with the recycled materials, although within levels commonly observed in the literature. Fracture tests indicate a complex behavior for re-recycled mixtures showing a similar response to the virgin materials for a higher amount of RAP. Only limited differences can be found when slag is used. The present experimental study seems to provide evidence on the possibility of combining re-recycled RAP and EAFSS to designing asphalt mixtures for pavement application.