EXPERIMENTAL APPLICATION OF SYNTHETIC LIGHTWEIGHT AGGREGATES FOR THE PRODUCTION OF SPECIAL ASPHALT CONCRETES

This paper presents the results of a laboratory research on asphalt concretes made with synthetic expanded aggregates produced from waste materials. In the last years, the use of wastes for the production of new construction materials is constantly increasing. In the present research, through the alkali-activation process, two different wastes are used for the production of synthetic lightweight aggregates: a digested spent bentonite clay and a basalt powder. Both experimental aggregates have been fully characterized in compliance with the reference standards for lightweight aggregates. Taking as a reference some Italian specifications for special wearing course asphalt concretes, the physical and mechanical properties of two different experimental asphalt mixtures have been evaluated. For this purpose, a mixture prepared with traditional expanded clay aggregates was used as reference material. The presented preliminary results indicate that the use of alkali-activated lightweight aggregate in total substitution of the expanded clay does not negatively affect the performances of the asphalt mixture. Moreover, the alkali-activation of these waste materials seems to be a suitable and sustainable solution for the production of lightweight aggregates for this and other purposes.