Fatigue performance of asphalt concretes with rap aggregates and steel slags

The results are presented of an experimental investigation and a theoretical study on the fatigue behaviour of asphalt concretes, determined by the four-point bending test, according to the EN 12697-24 Annex D standard. The testing was performed on bituminous mixtures, with Reclaimed Asphalt Pavement (RAP) aggregates and Electric Arc Furnace (EAF) steel slags, used at different proportions (up to 70% of the weight of the aggregates), in partial substitution for natural limestone. Fatigue life was evaluated by means of the conventional approach, related to a 50% reduction in the initial stiffness modulus, as well as using more rational concepts, related to the macro-structural damage condition of the mixtures, in terms of dissipated energy and damage accumulation. With respect to the control mixture with limestone aggregates, the asphalt concretes with RAP aggregate and EAF slags presented improved fatigue properties and delayed macro-crack initiation.