Experimental analysis of asphalt concrete modified with polymeric compounds including steel slags as an alternative to basaltic aggregates

Studying sustainable solutions in the infrastructure sector represents a strategical opportunity for reducing CO2 emissions and other relevant issues on the environment. Beyond innovations in vehicles, the construction sector is fully involved in this process for defining and promoting novel and more sustainable materials and technologies, but with adequate mechanical performance. In this regard, since the use of “non-traditional” materials may determine huge benefits, several studies confirmed the possibility (and opportunity) of use waste materials after appropriate recycling actions (aimed to reach performance and environmental requirements) even in novel constructions. In this study, an experimental analysis in laboratory was carried out to evaluate the possibility of use steel slag aggregates to be used in innovative surface asphalt mixtures. The experimental phases relied on the comparison of the performance offered by an innovative mixture with steel slags, with those offered by a traditional one, with natural limestone and basaltic aggregates only. For both mixtures, a polymeric compound was used together with an adhesion activator for balancing effects of the high percentages of silica that hinder satisfactory adhesion between binder and aggregates. The experimental results evidenced an overall equivalence between the two mixtures in terms of mechanical performance, with clear environmental benefits for mixture including steel slags, due to the reduction of virgin materials and bitumen percentages. Further, the experiments showed higher crushing resistance of steel slags, a relevant advantage in laying and compaction phases since this property favours avoiding or minimizing effects of grain size distribution variation due to aggregate crushing.