Improving the Compressive Strength of Reclaimed Asphalt Pavement Concretes with Silica Fume

A possible valorization of reclaimed asphalt pavement (RAP) aggregates resulting from flexible roads maintenance consists of introducing them in cement concrete compositions for road construction. However, experimental results reported in the literature show a relative loss in mechanical and elastic properties due to the RAP aggregate’s incorporation. The main objective of the present study is to improve the compressive strength of RAP concretes by using silica fume (SF) as a mineral admixture. Experimental results show that SF increases the compressive strength of RAP concretes as well as conventional concretes. A scanning electron microscopy analysis was carried out on specimens in order to confirm the conclusion of the experimental study. Finally, a 22 factorial design allowed the individual and combined effects of RAP and SF introduction on the compressive strength of 91-day concretes to be quantified. This approach has shown that 30% partial aggregate substitution and 10% silica fume reinforcement would give the concrete the characteristics required for its use in the construction of reinforced rigid pavements. Therefore, recycling RAP aggregates and SF in cement concretes can be considered as an ecological approach that respects the environment, within a sustainable development context of road networks.