Abstract—Waste recycling is a compelling topic worldwide, especially in construction whose development is becoming highly unsustainable. Production and characterization of novel eco-composite alkali-activated mortars are reported. Specimens consist of a geopolymeric binder that uses biomass fly ash from a kraft pulp industry admixed with traditional construction silica sand in various proportions. Mix design is studied to investigate the effects of sand incorporation on mortars characteristics. Moreover, the effects of age and water addiction are analysed. Finally, a sustainable and reproducible manufacture is followed. The performed analyses indicate that the novel mortars can be used as structural material in construction and represent an efficient solution to reduce the environmental footprint associated with waste disposal.