AAM FROM CDW MODIFIED BY BIOCHAR

The effect of the addition of small amounts (< 5 wt%) of biochar deriving from the slow rate pyrolysis of peach, grapevine and pruning wood on the physical and mechanical properties of alkali-activated materials (AAM) is investigated. Different binder compositions have been tested, starting from metakaolin as a first binder fraction and mixing it up to 50 wt% with crushed bricks and concrete wastes (CDW). At the same time, three fractions of biochar, respectively 1, 3 and 5 wt.%, have been added to all formulations. The fresh and cured properties of the materials have been investigated, as well as the mechanical behaviour. Moreover, water absorption by capillarity has been evaluated as a first insight into the durability of the materials. Data so far obtained underline how the lowest biochar amount (1 wt%) accelerates the development of the mechanical properties in all the different mixing binders. Only higher amounts of biochar (5%) can reduce the rate of water diffusion.