Sustainable asphalt mastics made up recycling waste as filler

The continuous growth of waste is generating worldwide more and more increasing related environmental concerns. Anything that is not recycled or recuperated from waste represents a loss of raw materials and other production factors used in the manufacture, transport and consumer phases of the product. This research explored the potential of three waste namely Construction and Demolition (CD) waste, Fly Ash (FA), and Jet Grouting (JG) waste as fillers in comparison to the traditional limestone one for making hot asphalt mastics for road pavement, through a rheological analysis and environmental compatibility tests towards the release of potentially toxic elements. A total of eight asphalt mastics were prepared by using two filler-to-binder weight ratios (f/b) of 0.5 and 1 for blending each filler with a neat bitumen 50/70 penetration grade. The Frequency Sweep test and the Multiple Stress Creep and Recovery (MSCR) test were carried out to investigate the rheological properties of the asphalt mastics. Asphalt mastics containing FA and JG fillers were found to be more mechanically and environmentally efficient than traditional limestone mastic in particular by adopting an f/b equal to 1 where it was observed higher complex shear modulus values, G*, (on average 50% compared to the traditional asphalt mastic) and lower non-recoverable creep compliance values, Jnr, (on average 35% compared to the traditional asphalt mastic) at all test temperatures investigated. Based on the suggested ranking methodology, CD emerged as the filler performing in the same way of the traditional one. All the waste containing mastics, showed up noticeable environmental compatibility, being the potentially toxic elements completely immobilized into the mastics’ structure e practically not releasable into acidic water, highlighting the waste recycling for road pavements as primary strategy to immobilize hazardous wastes.