Road Asphalt Pavements Made by Bottom Ashes from Waste-to-Energy Plant as a Filler

Not all waste is completely burned by waste-to-energy plants. About 73% of it is bottom ashes (BA). Sustainable reuse of the BA is to reprocess them into the production chain of the asphalt mixtures for road pavements. This research deals with an experimental investigation of the mechanical performance of hot and cold asphalt mastics made with the BA filler versus the traditional ones containing limestone powder (LP). First, environmental compatibility tests were carried out and then a rheological analysis, applying viscosity, frequency sweep, and multiple stress creep and recovery tests, was performed to check the feasibility of using the BA as a filler for asphalt-based materials. Looking at the main results, the ecotoxicological tests in terms of EC50 for toxicity on Daphnia and EC50 for algal growth inhibition confirmed the usability of all the mastics from an environmental point of view. The rheological results showed higher G* values for cold asphalt mastics made up with the BA compared to the corresponding solutions made with the LP. Additionally, it was also observed that the mastics containing BA returned a 90% decrease in non-recoverable creep compliance at test temperatures over 40°C compared to the corresponding mastics made with the LP.