Investigating the environmental and mechanical properties of sustainable asphalt mastic solutions for road flexible pavements

The circular economy is restorative in nature, and it aims to maintain the utility of products, components and materials for as long as possible while also retaining their value. It thus minimizes the need for new inputs of virgin materials and energy, while reducing environmental pressures linked to resource extraction, emissions and waste management. The research focus on the investigation of an innovative procedure for reusing the jet grouting waste (JGW) obtained from soil consolidation activities to produce high-performing sustainable road asphalt mastics (filler plus neat bitumen). The mastics under analysis were made at three different filler over bitumen ratios of 0.5, 1 and 1.5, in particular six were obtained with neat bitumen and other six at the same f/b ratios mixed with an aged bitumen after the RTFO procedure. The rheological properties of the mastics were investigated using a dynamic shear rheometer, and the performance of the innovative mastics was compared with that of the neat bitumen and traditional mastics made up of bitumen and limestone filler (LF). The main results of the initial step of the analysis showed that, at temperatures from 0 to 30°C, the shear moduli of the mastics containing JGW (MJGW) averaged 30% higher than the limestone mastic (ML) blended with an f/b ratio of 0.30. The life-cycle assessment impact category indicators were then calculated, highlighting the considerable environmental benefits of the innovative hot asphalt mastics in question. The primary outcomes showed that compared with the asphalt mastics containing LF, the asphalt mastic solution lowered terrestrial ecotoxicity by 53% and the freshwater eutrophication potential by up to 97%.