Rutting resistance of Stone Mastic Asphalts with steel slag and coal ash

The paper discusses the results of a laboratory investigation, aimed at verifying the rutting susceptibility of Stone Mastic Asphalt (SMA) mixes made with Electric Arc Furnace (EAF) steel slag and Coal Ash (CA), used at different proportions, in partial substitution of natural limestone and filler. The experimental study has been focused on the leaching, physical and mechanical properties of the marginal materials, as well as on the mix design, based on the Bailey method and the moisture resistance of the asphalt concretes. The permanent deformation resistance of the SMA mixes has been investigated by means of Repeated Load Axial Tests and Wheel Tracking Tests. With respect to the SMA mixes made with natural aggregate, the use of the EAF slag, up to 40%, increases consistently the rutting resistance, and allows the recycling of marginal aggregates up to 50% by weight, so providing more environmentally sustainable design solutions for high performance flexible pavements.