Bituminous Mixtures with High Environmental Compatibility: Laboratory Investigation on the Use of Reclaimed Asphalt and Steel Slag Aggregates

Recycling waste materials is a key issue in sustainable road pavements construction. This is the reason why the efforts of the scientific and technical community are addressed in studying sustainable solutions for producing bituminous mixtures. As a result of these efforts, the use of Reclaimed Asphalt (RA) is becoming a standard practice, even if in Italy the use of RA is limited to a certain content. So the increase of RA content appears to be the new border of the research in this field. At the same time, the scientific literature demonstrates that other recycled materials, such as Steel Slags Aggregates (SSAs), can be used with satisfactory results. To go a step further, the research herein described focused on the evaluation, at the laboratory scale, of the effects of both high amounts of RA (from 15 up to 60% by weight) and RA plus SSAs (from 55 up to 71% by weight). Compaction properties, volumetric characteristics and mechanical performances were investigated. Even if the obtained results are at the laboratory scale and keeping in mind that the research needs an on-site validation, the investigated mixtures seem to be promising for a future development of bituminous mixtures with high environmental compatibility.