THE ALKALI-ACTIVATION OF CONSTRUCTION AND DEMOLITION WASTE COMPONENTS FOR STABILIZATION PURPOSES

This study investigates the potential of the different components of CDW (recycled concrete RC, recycled asphalt RA, crushed bricks and tiles BT, natural aggregate NA, and undivided CDW UND) to undergo alkali activation (AA) when mixed with an appropriate alkaline solution (AS). The feasibility of the AA of CDW fines for the stabilization of CDW aggregates was evaluated for particles smaller than 0,125 mm. A preliminary chemical characterization was carried out on different components of CDW aggregates to identify the main crystalline phases and ascertain the presence of aluminosilicates needed for the AA process. Particles of each component were afterwards mixed with three concentrations of the same AS, cast in prismatic moulds, and cured at room temperature without any thermal treatment. Mechanical tests after 3, 7, and 28 days of curing demonstrated that CDW fine powders tend to react positively in a basic environment, showing an increase in strength without any thermal treatment. These results can be translated into practical applications in the form of a methodology for improving pavement layers made up of CDW aggregates without the addition of any cementitious binders.