Alkali-Activated Mortars Incorporating Construction and Demolition Waste and Industrial By-products: A Fresh and Hardened State Evaluation

Abstract

This study examines the potential of alkali-activated composites to produce sustainable building materials by recycling construction and demolition waste (CDW). Various waste materials such as ground granulated blast furnace slag (GGBS), class F and C fly ash (FA), recycled waste clay brick powder (RWBP), and waste concrete powder (WCP) were used to produce different alkali-activated composites along with recycled concrete aggregate. The prepared mixtures were analyzed for their fresh-state properties, as well as their physical and mechanical characteristics, including workability, strength, ultrasonic pulse velocity (UPV), and resistance to high temperatures. The findings indicate that mixtures with class C fly ash achieved higher compressive strength, whereas F class fly ash positively affected workability and high-temperature resistance. Slag effectively enhanced the compressive strength of the alkali-activated composites. In particular, the B3 mixture (20% class F fly ash, 40% slag) exhibited a balanced set of properties in terms of workability, compressive strength, and high-temperature performance. This study provides a valuable resource for producing alkali-activated composites from CDW and industrial waste, with the potential to reduce the environmental impact of the construction sector.